diff options
Diffstat (limited to 'sys-kernel/linux-sources-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch')
| -rw-r--r-- | sys-kernel/linux-sources-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch | 18511 |
1 files changed, 18511 insertions, 0 deletions
diff --git a/sys-kernel/linux-sources-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch b/sys-kernel/linux-sources-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch new file mode 100644 index 00000000..039c8fcd --- /dev/null +++ b/sys-kernel/linux-sources-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch @@ -0,0 +1,18511 @@ +diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt +index 8d8d8f06cab2..41d0200944f1 100644 +--- a/Documentation/block/bfq-iosched.txt ++++ b/Documentation/block/bfq-iosched.txt +@@ -1,3 +1,6 @@ ++[ THIS TREE CONTAINS ALSO THE DEV VERSION OF BFQ. ++ DETAILS AT THE END OF THIS DOCUMENT. ] ++ + BFQ (Budget Fair Queueing) + ========================== + +@@ -11,6 +14,15 @@ controllers), BFQ's main features are: + groups (switching back to time distribution when needed to keep + throughput high). + ++If bfq-mq patches have been applied, then the following three ++instances of BFQ are available (otherwise only the first instance): ++- bfq: mainline version of BFQ, for blk-mq ++- bfq-mq: development version of BFQ for blk-mq; this version contains ++ also all latest features and fixes not yet landed in mainline, plus many ++ safety checks ++- bfq-sq: BFQ for legacy blk; also this version contains latest features ++ and fixes, as well as safety checks ++ + In its default configuration, BFQ privileges latency over + throughput. So, when needed for achieving a lower latency, BFQ builds + schedules that may lead to a lower throughput. If your main or only +@@ -22,27 +34,42 @@ latency and throughput, or on how to maximize throughput. + + BFQ has a non-null overhead, which limits the maximum IOPS that a CPU + can process for a device scheduled with BFQ. To give an idea of the +-limits on slow or average CPUs, here are, first, the limits of BFQ for +-three different CPUs, on, respectively, an average laptop, an old +-desktop, and a cheap embedded system, in case full hierarchical +-support is enabled (i.e., CONFIG_BFQ_GROUP_IOSCHED is set), but ++limits on slow or average CPUs, here are, first, the limits of bfq-mq ++and bfq for three different CPUs, on, respectively, an average laptop, ++an old desktop, and a cheap embedded system, in case full hierarchical ++support is enabled (i.e., CONFIG_MQ_BFQ_GROUP_IOSCHED is set for ++bfq-mq, or CONFIG_BFQ_GROUP_IOSCHED is set for bfq), but + CONFIG_DEBUG_BLK_CGROUP is not set (Section 4-2): + - Intel i7-4850HQ: 400 KIOPS + - AMD A8-3850: 250 KIOPS + - ARM CortexTM-A53 Octa-core: 80 KIOPS + +-If CONFIG_DEBUG_BLK_CGROUP is set (and of course full hierarchical +-support is enabled), then the sustainable throughput with BFQ +-decreases, because all blkio.bfq* statistics are created and updated +-(Section 4-2). For BFQ, this leads to the following maximum +-sustainable throughputs, on the same systems as above: ++As for bfq-sq, it cannot reach the above IOPS, because of the ++inherent, lower parallelism of legacy blk and of the components within ++it (including bfq-sq itself). In particular, results with ++CONFIG_DEBUG_BLK_CGROUP unset are rather fluctuating. The limits ++reported below for the case CONFIG_DEBUG_BLK_CGROUP set will however ++provide a lower bound to the limits of bfq-sq. ++ ++Turning back to bfq-mq and bfq, If CONFIG_DEBUG_BLK_CGROUP is set (and ++of course full hierarchical support is enabled), then the sustainable ++throughput with bfq-mq and bfq decreases, because all blkio.bfq* ++statistics are created and updated (Section 4-2). For bfq-mq and bfq, ++this leads to the following maximum sustainable throughputs, on the ++same systems as above: + - Intel i7-4850HQ: 310 KIOPS + - AMD A8-3850: 200 KIOPS + - ARM CortexTM-A53 Octa-core: 56 KIOPS + +-BFQ works for multi-queue devices too. ++Finally, if CONFIG_DEBUG_BLK_CGROUP is set (and full hierarchical ++support is enabled), then bfq-sq exhibits the following limits: ++- Intel i7-4850HQ: 250 KIOPS ++- AMD A8-3850: 170 KIOPS ++- ARM CortexTM-A53 Octa-core: 45 KIOPS + +-The table of contents follow. Impatients can just jump to Section 3. ++BFQ works for multi-queue devices too (bfq and bfq-mq instances). ++ ++The table of contents follows. Impatients can just jump to Section 3. + + CONTENTS + +@@ -509,25 +536,27 @@ To get proportional sharing of bandwidth with BFQ for a given device, + BFQ must of course be the active scheduler for that device. + + Within each group directory, the names of the files associated with +-BFQ-specific cgroup parameters and stats begin with the "bfq." +-prefix. So, with cgroups-v1 or cgroups-v2, the full prefix for +-BFQ-specific files is "blkio.bfq." or "io.bfq." For example, the group +-parameter to set the weight of a group with BFQ is blkio.bfq.weight ++BFQ-specific cgroup parameters and stats begin with the "bfq.", ++"bfq-sq." or "bfq-mq." prefix, depending on which instance of bfq you ++want to use. So, with cgroups-v1 or cgroups-v2, the full prefix for ++BFQ-specific files is "blkio.bfqX." or "io.bfqX.", where X can be "" ++(i.e., null string), "-sq" or "-mq". For example, the group parameter ++to set the weight of a group with the mainline BFQ is blkio.bfq.weight + or io.bfq.weight. + + As for cgroups-v1 (blkio controller), the exact set of stat files +-created, and kept up-to-date by bfq, depends on whether +-CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq creates all ++created, and kept up-to-date by bfq*, depends on whether ++CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq* creates all + the stat files documented in + Documentation/cgroup-v1/blkio-controller.txt. If, instead, +-CONFIG_DEBUG_BLK_CGROUP is not set, then bfq creates only the files +-blkio.bfq.io_service_bytes +-blkio.bfq.io_service_bytes_recursive +-blkio.bfq.io_serviced +-blkio.bfq.io_serviced_recursive ++CONFIG_DEBUG_BLK_CGROUP is not set, then bfq* creates only the files ++blkio.bfq*.io_service_bytes ++blkio.bfq*.io_service_bytes_recursive ++blkio.bfq*.io_serviced ++blkio.bfq*.io_serviced_recursive + + The value of CONFIG_DEBUG_BLK_CGROUP greatly influences the maximum +-throughput sustainable with bfq, because updating the blkio.bfq.* ++throughput sustainable with bfq*, because updating the blkio.bfq* + stats is rather costly, especially for some of the stats enabled by + CONFIG_DEBUG_BLK_CGROUP. + +@@ -536,7 +565,7 @@ Parameters to set + + For each group, there is only the following parameter to set. + +-weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the ++weight (namely blkio.bfqX.weight or io.bfqX.weight): the weight of the + group inside its parent. Available values: 1..10000 (default 100). The + linear mapping between ioprio and weights, described at the beginning + of the tunable section, is still valid, but all weights higher than +@@ -559,3 +588,55 @@ applications. Unset this tunable if you need/want to control weights. + Slightly extended version: + http://algogroup.unimore.it/people/paolo/disk_sched/bfq-v1-suite- + results.pdf ++ ++---------------------------------------------------------------------- ++ ++DETAILS ON THE DEV VERSIONS IN THIS TREE ++ ++The dev version of BFQ is available for both the legacy and the ++multi-queue block layers, as two additional I/O schedulers, named, ++respectively, bfq-sq-iosched and bfq-mq-iosched (the latter is ++available if also the changes introducing bfq-mq-iosched have been ++applied). In particular, this tree contains the dev version of bfq for ++Linux mainline 4.19.0, and has been obtained from the dev version for ++Linux 4.18.0. Rebasing from 4.18 to 4.19 involved two manual ++interventions. ++ ++First, some conflicts had to be resolved, as follows: ++ ++--------------------------------------------------------------- ++ ++diff --cc Makefile ++index 7727c1bf6fa5,69fa5c0310d8..c7cbdf0ad594 ++--- a/Makefile +++++ b/Makefile ++@@@ -1,9 -1,9 +1,9 @@@ ++ # SPDX-License-Identifier: GPL-2.0 ++ VERSION = 4 ++- PATCHLEVEL = 18 +++ PATCHLEVEL = 19 ++ SUBLEVEL = 0 ++ -EXTRAVERSION = ++ +EXTRAVERSION = -bfq-mq ++- NAME = Merciless Moray +++ NAME = "People's Front" ++ ++ # *DOCUMENTATION* ++ # To see a list of typical targets execute "make help" ++diff --cc include/linux/blkdev.h ++index 897c63322bd7,6980014357d4..8c4568ea6884 ++--- a/include/linux/blkdev.h +++++ b/include/linux/blkdev.h ++@@@ -56,7 -54,7 +54,7 @@@ struct blk_stat_callback ++ * Maximum number of blkcg policies allowed to be registered concurrently. ++ * Defined here to simplify include dependency. ++ */ ++--#define BLKCG_MAX_POLS 5 ++++#define BLKCG_MAX_POLS 7 ++ ++ typedef void (rq_end_io_fn)(struct request *, blk_status_t); ++ ++--------------------------------------------------------------- ++ ++Second, the following port commit had to be made: ++port commit "block: use ktime_get_ns() instead of sched_clock() for cfq and bfq" +diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig +index e32fc1f274d8..94cb28eb20ba 100644 +--- a/arch/x86/configs/x86_64_defconfig ++++ b/arch/x86/configs/x86_64_defconfig +@@ -12,6 +12,11 @@ CONFIG_NO_HZ=y + CONFIG_HIGH_RES_TIMERS=y + CONFIG_LOG_BUF_SHIFT=18 + CONFIG_CGROUPS=y ++CONFIG_BLK_CGROUP=y ++CONFIG_IOSCHED_BFQ_SQ=y ++CONFIG_BFQ_SQ_GROUP_IOSCHED=y ++CONFIG_MQ_IOSCHED_BFQ=y ++CONFIG_MQ_BFQ_GROUP_IOSCHED=y + CONFIG_CGROUP_FREEZER=y + CONFIG_CPUSETS=y + CONFIG_CGROUP_CPUACCT=y +diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched +index a4a8914bf7a4..299a6861fb90 100644 +--- a/block/Kconfig.iosched ++++ b/block/Kconfig.iosched +@@ -40,6 +40,26 @@ config CFQ_GROUP_IOSCHED + ---help--- + Enable group IO scheduling in CFQ. + ++config IOSCHED_BFQ_SQ ++ tristate "BFQ-SQ I/O scheduler" ++ default n ++ ---help--- ++ The BFQ-SQ I/O scheduler (for legacy blk: SQ stands for ++ SingleQueue) distributes bandwidth among all processes ++ according to their weights, regardless of the device ++ parameters and with any workload. It also guarantees a low ++ latency to interactive and soft real-time applications. ++ Details in Documentation/block/bfq-iosched.txt ++ ++config BFQ_SQ_GROUP_IOSCHED ++ bool "BFQ-SQ hierarchical scheduling support" ++ depends on IOSCHED_BFQ_SQ && BLK_CGROUP ++ default n ++ ---help--- ++ ++ Enable hierarchical scheduling in BFQ-SQ, using the blkio ++ (cgroups-v1) or io (cgroups-v2) controller. ++ + choice + + prompt "Default I/O scheduler" +@@ -54,6 +74,16 @@ choice + config DEFAULT_CFQ + bool "CFQ" if IOSCHED_CFQ=y + ++ config DEFAULT_BFQ_SQ ++ bool "BFQ-SQ" if IOSCHED_BFQ_SQ=y ++ help ++ Selects BFQ-SQ as the default I/O scheduler which will be ++ used by default for all block devices. ++ The BFQ-SQ I/O scheduler aims at distributing the bandwidth ++ as desired, independently of the disk parameters and with ++ any workload. It also tries to guarantee low latency to ++ interactive and soft real-time applications. ++ + config DEFAULT_NOOP + bool "No-op" + +@@ -63,8 +93,28 @@ config DEFAULT_IOSCHED + string + default "deadline" if DEFAULT_DEADLINE + default "cfq" if DEFAULT_CFQ ++ default "bfq-sq" if DEFAULT_BFQ_SQ + default "noop" if DEFAULT_NOOP + ++config MQ_IOSCHED_BFQ ++ tristate "BFQ-MQ I/O Scheduler" ++ default y ++ ---help--- ++ BFQ I/O scheduler for BLK-MQ. BFQ-MQ distributes bandwidth ++ among all processes according to their weights, regardless of ++ the device parameters and with any workload. It also ++ guarantees a low latency to interactive and soft real-time ++ applications. Details in Documentation/block/bfq-iosched.txt ++ ++config MQ_BFQ_GROUP_IOSCHED ++ bool "BFQ-MQ hierarchical scheduling support" ++ depends on MQ_IOSCHED_BFQ && BLK_CGROUP ++ default n ++ ---help--- ++ ++ Enable hierarchical scheduling in BFQ-MQ, using the blkio ++ (cgroups-v1) or io (cgroups-v2) controller. ++ + config MQ_IOSCHED_DEADLINE + tristate "MQ deadline I/O scheduler" + default y +diff --git a/block/Makefile b/block/Makefile +index 572b33f32c07..1dd6ffdc2fee 100644 +--- a/block/Makefile ++++ b/block/Makefile +@@ -25,6 +25,8 @@ obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o + obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o + bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o + obj-$(CONFIG_IOSCHED_BFQ) += bfq.o ++obj-$(CONFIG_IOSCHED_BFQ_SQ) += bfq-sq-iosched.o ++obj-$(CONFIG_MQ_IOSCHED_BFQ) += bfq-mq-iosched.o + + obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o + obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o +diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c +new file mode 100644 +index 000000000000..15459e50cd6a +--- /dev/null ++++ b/block/bfq-cgroup-included.c +@@ -0,0 +1,1359 @@ ++/* ++ * BFQ: CGROUPS support. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org> ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ */ ++ ++#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP) ++ ++/* bfqg stats flags */ ++enum bfqg_stats_flags { ++ BFQG_stats_waiting = 0, ++ BFQG_stats_idling, ++ BFQG_stats_empty, ++}; ++ ++#define BFQG_FLAG_FNS(name) \ ++static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ ++{ \ ++ stats->flags |= (1 << BFQG_stats_##name); \ ++} \ ++static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ ++{ \ ++ stats->flags &= ~(1 << BFQG_stats_##name); \ ++} \ ++static int bfqg_stats_##name(struct bfqg_stats *stats) \ ++{ \ ++ return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ ++} \ ++ ++BFQG_FLAG_FNS(waiting) ++BFQG_FLAG_FNS(idling) ++BFQG_FLAG_FNS(empty) ++#undef BFQG_FLAG_FNS ++ ++#ifdef BFQ_MQ ++/* This should be called with the scheduler lock held. */ ++#else ++/* This should be called with the queue_lock held. */ ++#endif ++static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) ++{ ++ u64 now; ++ ++ if (!bfqg_stats_waiting(stats)) ++ return; ++ ++ now = ktime_get_ns(); ++ if (now > stats->start_group_wait_time) ++ blkg_stat_add(&stats->group_wait_time, ++ now - stats->start_group_wait_time); ++ bfqg_stats_clear_waiting(stats); ++} ++ ++#ifdef BFQ_MQ ++/* This should be called with the scheduler lock held. */ ++#else ++/* This should be called with the queue_lock held. */ ++#endif ++static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, ++ struct bfq_group *curr_bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (bfqg_stats_waiting(stats)) ++ return; ++ if (bfqg == curr_bfqg) ++ return; ++ stats->start_group_wait_time = ktime_get_ns(); ++ bfqg_stats_mark_waiting(stats); ++} ++ ++#ifdef BFQ_MQ ++/* This should be called with the scheduler lock held. */ ++#else ++/* This should be called with the queue_lock held. */ ++#endif ++static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) ++{ ++ u64 now; ++ ++ if (!bfqg_stats_empty(stats)) ++ return; ++ ++ now = ktime_get_ns(); ++ if (now > stats->start_empty_time) ++ blkg_stat_add(&stats->empty_time, ++ now - stats->start_empty_time); ++ bfqg_stats_clear_empty(stats); ++} ++ ++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg) ++{ ++ blkg_stat_add(&bfqg->stats.dequeue, 1); ++} ++ ++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (blkg_rwstat_total(&stats->queued)) ++ return; ++ ++ /* ++ * group is already marked empty. This can happen if bfqq got new ++ * request in parent group and moved to this group while being added ++ * to service tree. Just ignore the event and move on. ++ */ ++ if (bfqg_stats_empty(stats)) ++ return; ++ ++ stats->start_empty_time = ktime_get_ns(); ++ bfqg_stats_mark_empty(stats); ++} ++ ++static void bfqg_stats_update_idle_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (bfqg_stats_idling(stats)) { ++ u64 now = ktime_get_ns(); ++ ++ if (now > stats->start_idle_time) ++ blkg_stat_add(&stats->idle_time, ++ now - stats->start_idle_time); ++ bfqg_stats_clear_idling(stats); ++ } ++} ++ ++static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ stats->start_idle_time = ktime_get_ns(); ++ bfqg_stats_mark_idling(stats); ++} ++ ++static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ blkg_stat_add(&stats->avg_queue_size_sum, ++ blkg_rwstat_total(&stats->queued)); ++ blkg_stat_add(&stats->avg_queue_size_samples, 1); ++ bfqg_stats_update_group_wait_time(stats); ++} ++ ++static void bfqg_stats_update_io_add(struct bfq_group *bfqg, ++ struct bfq_queue *bfqq, ++ unsigned int op) ++{ ++ blkg_rwstat_add(&bfqg->stats.queued, op, 1); ++ bfqg_stats_end_empty_time(&bfqg->stats); ++ if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) ++ bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); ++} ++ ++static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) ++{ ++ blkg_rwstat_add(&bfqg->stats.queued, op, -1); ++} ++ ++static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) ++{ ++ blkg_rwstat_add(&bfqg->stats.merged, op, 1); ++} ++ ++static void bfqg_stats_update_completion(struct bfq_group *bfqg, ++ u64 start_time_ns, ++ u64 io_start_time_ns, ++ unsigned int op) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ u64 now = ktime_get_ns(); ++ ++ if (now > io_start_time_ns) ++ blkg_rwstat_add(&stats->service_time, op, ++ now - io_start_time_ns); ++ if (io_start_time_ns > start_time_ns) ++ blkg_rwstat_add(&stats->wait_time, op, ++ io_start_time_ns - start_time_ns); ++} ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */ ++ ++static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg, ++ struct bfq_queue *bfqq, unsigned int op) { } ++static inline void ++bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } ++static inline void ++bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } ++static inline void bfqg_stats_update_completion(struct bfq_group *bfqg, ++ u64 start_time_ns, ++ u64 io_start_time_ns, ++ unsigned int op) { } ++static inline void ++bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, ++ struct bfq_group *curr_bfqg) { } ++static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { } ++static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */ ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct blkcg_policy blkcg_policy_bfq; ++ ++/* ++ * blk-cgroup policy-related handlers ++ * The following functions help in converting between blk-cgroup ++ * internal structures and BFQ-specific structures. ++ */ ++ ++static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) ++{ ++ return pd ? container_of(pd, struct bfq_group, pd) : NULL; ++} ++ ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) ++{ ++ return pd_to_blkg(&bfqg->pd); ++} ++ ++static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) ++{ ++ struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq); ++ ++ return pd_to_bfqg(pd); ++} ++ ++/* ++ * bfq_group handlers ++ * The following functions help in navigating the bfq_group hierarchy ++ * by allowing to find the parent of a bfq_group or the bfq_group ++ * associated to a bfq_queue. ++ */ ++ ++static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) ++{ ++ struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; ++ ++ return pblkg ? blkg_to_bfqg(pblkg) : NULL; ++} ++ ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *group_entity = bfqq->entity.parent; ++ ++ return group_entity ? container_of(group_entity, struct bfq_group, ++ entity) : ++ bfqq->bfqd->root_group; ++} ++ ++/* ++ * The following two functions handle get and put of a bfq_group by ++ * wrapping the related blk-cgroup hooks. ++ */ ++ ++static void bfqg_get(struct bfq_group *bfqg) ++{ ++#ifdef BFQ_MQ ++ bfqg->ref++; ++#else ++ blkg_get(bfqg_to_blkg(bfqg)); ++#endif ++} ++ ++static void bfqg_put(struct bfq_group *bfqg) ++{ ++#ifdef BFQ_MQ ++ bfqg->ref--; ++ ++ BUG_ON(bfqg->ref < 0); ++ if (bfqg->ref == 0) ++ kfree(bfqg); ++#else ++ blkg_put(bfqg_to_blkg(bfqg)); ++#endif ++} ++ ++#ifdef BFQ_MQ ++static void bfqg_and_blkg_get(struct bfq_group *bfqg) ++{ ++ /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */ ++ bfqg_get(bfqg); ++ ++ blkg_get(bfqg_to_blkg(bfqg)); ++} ++ ++static void bfqg_and_blkg_put(struct bfq_group *bfqg) ++{ ++ blkg_put(bfqg_to_blkg(bfqg)); ++ ++ bfqg_put(bfqg); ++} ++#endif ++ ++/* @stats = 0 */ ++static void bfqg_stats_reset(struct bfqg_stats *stats) ++{ ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ /* queued stats shouldn't be cleared */ ++ blkg_rwstat_reset(&stats->merged); ++ blkg_rwstat_reset(&stats->service_time); ++ blkg_rwstat_reset(&stats->wait_time); ++ blkg_stat_reset(&stats->time); ++ blkg_stat_reset(&stats->avg_queue_size_sum); ++ blkg_stat_reset(&stats->avg_queue_size_samples); ++ blkg_stat_reset(&stats->dequeue); ++ blkg_stat_reset(&stats->group_wait_time); ++ blkg_stat_reset(&stats->idle_time); ++ blkg_stat_reset(&stats->empty_time); ++#endif ++} ++ ++/* @to += @from */ ++static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) ++{ ++ if (!to || !from) ++ return; ++ ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ /* queued stats shouldn't be cleared */ ++ blkg_rwstat_add_aux(&to->merged, &from->merged); ++ blkg_rwstat_add_aux(&to->service_time, &from->service_time); ++ blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); ++ blkg_stat_add_aux(&from->time, &from->time); ++ blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); ++ blkg_stat_add_aux(&to->avg_queue_size_samples, ++ &from->avg_queue_size_samples); ++ blkg_stat_add_aux(&to->dequeue, &from->dequeue); ++ blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); ++ blkg_stat_add_aux(&to->idle_time, &from->idle_time); ++ blkg_stat_add_aux(&to->empty_time, &from->empty_time); ++#endif ++} ++ ++/* ++ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors' ++ * recursive stats can still account for the amount used by this bfqg after ++ * it's gone. ++ */ ++static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) ++{ ++ struct bfq_group *parent; ++ ++ if (!bfqg) /* root_group */ ++ return; ++ ++ parent = bfqg_parent(bfqg); ++ ++ lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); ++ ++ if (unlikely(!parent)) ++ return; ++ ++ bfqg_stats_add_aux(&parent->stats, &bfqg->stats); ++ bfqg_stats_reset(&bfqg->stats); ++} ++ ++static void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) { ++ bfqq->ioprio = bfqq->new_ioprio; ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++#ifdef BFQ_MQ ++ /* ++ * Make sure that bfqg and its associated blkg do not ++ * disappear before entity. ++ */ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "getting bfqg %p and blkg\n", ++ bfqg); ++ ++ bfqg_and_blkg_get(bfqg); ++#else ++ bfqg_get(bfqg); ++#endif ++ } ++ entity->parent = bfqg->my_entity; /* NULL for root group */ ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static void bfqg_stats_exit(struct bfqg_stats *stats) ++{ ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ blkg_rwstat_exit(&stats->merged); ++ blkg_rwstat_exit(&stats->service_time); ++ blkg_rwstat_exit(&stats->wait_time); ++ blkg_rwstat_exit(&stats->queued); ++ blkg_stat_exit(&stats->time); ++ blkg_stat_exit(&stats->avg_queue_size_sum); ++ blkg_stat_exit(&stats->avg_queue_size_samples); ++ blkg_stat_exit(&stats->dequeue); ++ blkg_stat_exit(&stats->group_wait_time); ++ blkg_stat_exit(&stats->idle_time); ++ blkg_stat_exit(&stats->empty_time); ++#endif ++} ++ ++static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) ++{ ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ if (blkg_rwstat_init(&stats->merged, gfp) || ++ blkg_rwstat_init(&stats->service_time, gfp) || ++ blkg_rwstat_init(&stats->wait_time, gfp) || ++ blkg_rwstat_init(&stats->queued, gfp) || ++ blkg_stat_init(&stats->time, gfp) || ++ blkg_stat_init(&stats->avg_queue_size_sum, gfp) || ++ blkg_stat_init(&stats->avg_queue_size_samples, gfp) || ++ blkg_stat_init(&stats->dequeue, gfp) || ++ blkg_stat_init(&stats->group_wait_time, gfp) || ++ blkg_stat_init(&stats->idle_time, gfp) || ++ blkg_stat_init(&stats->empty_time, gfp)) { ++ bfqg_stats_exit(stats); ++ return -ENOMEM; ++ } ++#endif ++ ++ return 0; ++} ++ ++static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) ++{ ++ return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; ++} ++ ++static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) ++{ ++ return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); ++} ++ ++static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) ++{ ++ struct bfq_group_data *bgd; ++ ++ bgd = kzalloc(sizeof(*bgd), gfp); ++ if (!bgd) ++ return NULL; ++ return &bgd->pd; ++} ++ ++static void bfq_cpd_init(struct blkcg_policy_data *cpd) ++{ ++ struct bfq_group_data *d = cpd_to_bfqgd(cpd); ++ ++ d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? ++ CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; ++} ++ ++static void bfq_cpd_free(struct blkcg_policy_data *cpd) ++{ ++ kfree(cpd_to_bfqgd(cpd)); ++} ++ ++static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) ++{ ++ struct bfq_group *bfqg; ++ ++ bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); ++ if (!bfqg) ++ return NULL; ++ ++ if (bfqg_stats_init(&bfqg->stats, gfp)) { ++ kfree(bfqg); ++ return NULL; ++ } ++#ifdef BFQ_MQ ++ /* see comments in bfq_bic_update_cgroup for why refcounting */ ++ bfqg_get(bfqg); ++#endif ++ return &bfqg->pd; ++} ++ ++static void bfq_pd_init(struct blkg_policy_data *pd) ++{ ++ struct blkcg_gq *blkg; ++ struct bfq_group *bfqg; ++ struct bfq_data *bfqd; ++ struct bfq_entity *entity; ++ struct bfq_group_data *d; ++ ++ blkg = pd_to_blkg(pd); ++ BUG_ON(!blkg); ++ bfqg = blkg_to_bfqg(blkg); ++ bfqd = blkg->q->elevator->elevator_data; ++ BUG_ON(bfqg == bfqd->root_group); ++ entity = &bfqg->entity; ++ d = blkcg_to_bfqgd(blkg->blkcg); ++ ++ entity->orig_weight = entity->weight = entity->new_weight = d->weight; ++ entity->my_sched_data = &bfqg->sched_data; ++ bfqg->my_entity = entity; /* ++ * the root_group's will be set to NULL ++ * in bfq_init_queue() ++ */ ++ bfqg->bfqd = bfqd; ++ bfqg->active_entities = 0; ++ bfqg->rq_pos_tree = RB_ROOT; ++} ++ ++static void bfq_pd_free(struct blkg_policy_data *pd) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ ++ bfqg_stats_exit(&bfqg->stats); ++#ifdef BFQ_MQ ++ bfqg_put(bfqg); ++#else ++ kfree(bfqg); ++#endif ++} ++ ++static void bfq_pd_reset_stats(struct blkg_policy_data *pd) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ ++ bfqg_stats_reset(&bfqg->stats); ++} ++ ++static void bfq_group_set_parent(struct bfq_group *bfqg, ++ struct bfq_group *parent) ++{ ++ struct bfq_entity *entity; ++ ++ BUG_ON(!parent); ++ BUG_ON(!bfqg); ++ BUG_ON(bfqg == parent); ++ ++ entity = &bfqg->entity; ++ entity->parent = parent->my_entity; ++ entity->sched_data = &parent->sched_data; ++} ++ ++static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, ++ struct blkcg *blkcg) ++{ ++ struct blkcg_gq *blkg; ++ ++ blkg = blkg_lookup(blkcg, bfqd->queue); ++ if (likely(blkg)) ++ return blkg_to_bfqg(blkg); ++ return NULL; ++} ++ ++static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, ++ struct blkcg *blkcg) ++{ ++ struct bfq_group *bfqg, *parent; ++ struct bfq_entity *entity; ++ ++ bfqg = bfq_lookup_bfqg(bfqd, blkcg); ++ ++ if (unlikely(!bfqg)) ++ return NULL; ++ ++ /* ++ * Update chain of bfq_groups as we might be handling a leaf group ++ * which, along with some of its relatives, has not been hooked yet ++ * to the private hierarchy of BFQ. ++ */ ++ entity = &bfqg->entity; ++ for_each_entity(entity) { ++ bfqg = container_of(entity, struct bfq_group, entity); ++ BUG_ON(!bfqg); ++ if (bfqg != bfqd->root_group) { ++ parent = bfqg_parent(bfqg); ++ if (!parent) ++ parent = bfqd->root_group; ++ BUG_ON(!parent); ++ bfq_group_set_parent(bfqg, parent); ++ } ++ } ++ ++ return bfqg; ++} ++ ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq); ++ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason); ++ ++/** ++ * bfq_bfqq_move - migrate @bfqq to @bfqg. ++ * @bfqd: queue descriptor. ++ * @bfqq: the queue to move. ++ * @bfqg: the group to move to. ++ * ++ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating ++ * it on the new one. Avoid putting the entity on the old group idle tree. ++ * ++#ifdef BFQ_MQ ++ * Must be called under the scheduler lock, to make sure that the blkg ++ * owning @bfqg does not disappear (see comments in ++ * bfq_bic_update_cgroup on guaranteeing the consistency of blkg ++ * objects). ++#else ++ * Must be called under the queue lock; the cgroup owning @bfqg must ++ * not disappear (by now this just means that we are called under ++ * rcu_read_lock()). ++#endif ++ */ ++static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st); ++ BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list) ++ && entity->on_st && ++ bfqq != bfqd->in_service_queue); ++ BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue); ++ ++ /* If bfqq is empty, then bfq_bfqq_expire also invokes ++ * bfq_del_bfqq_busy, thereby removing bfqq and its entity ++ * from data structures related to current group. Otherwise we ++ * need to remove bfqq explicitly with bfq_deactivate_bfqq, as ++ * we do below. ++ */ ++ if (bfqq == bfqd->in_service_queue) ++ bfq_bfqq_expire(bfqd, bfqd->in_service_queue, ++ false, BFQ_BFQQ_PREEMPTED); ++ ++ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq) ++ && &bfq_entity_service_tree(entity)->idle != ++ entity->tree); ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq)); ++ ++ if (bfq_bfqq_busy(bfqq)) ++ bfq_deactivate_bfqq(bfqd, bfqq, false, false); ++ else if (entity->on_st) { ++ BUG_ON(&bfq_entity_service_tree(entity)->idle != ++ entity->tree); ++ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); ++ } ++#ifdef BFQ_MQ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg); ++ ++ bfqg_and_blkg_put(bfqq_group(bfqq)); ++#else ++ bfqg_put(bfqq_group(bfqq)); ++#endif ++ ++ entity->parent = bfqg->my_entity; ++ entity->sched_data = &bfqg->sched_data; ++#ifdef BFQ_MQ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "getting blkg and bfqg %p\n", bfqg); ++ ++ /* pin down bfqg and its associated blkg */ ++ bfqg_and_blkg_get(bfqg); ++#else ++ bfqg_get(bfqg); ++#endif ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq)); ++ if (bfq_bfqq_busy(bfqq)) { ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ bfq_activate_bfqq(bfqd, bfqq); ++ } ++ ++ if (!bfqd->in_service_queue && !bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq) ++ && &bfq_entity_service_tree(entity)->idle != ++ entity->tree); ++} ++ ++/** ++ * __bfq_bic_change_cgroup - move @bic to @cgroup. ++ * @bfqd: the queue descriptor. ++ * @bic: the bic to move. ++ * @blkcg: the blk-cgroup to move to. ++ * ++#ifdef BFQ_MQ ++ * Move bic to blkcg, assuming that bfqd->lock is held; which makes ++ * sure that the reference to cgroup is valid across the call (see ++ * comments in bfq_bic_update_cgroup on this issue) ++#else ++ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller ++ * has to make sure that the reference to cgroup is valid across the call. ++#endif ++ * ++ * NOTE: an alternative approach might have been to store the current ++ * cgroup in bfqq and getting a reference to it, reducing the lookup ++ * time here, at the price of slightly more complex code. ++ */ ++static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, ++ struct blkcg *blkcg) ++{ ++ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); ++ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); ++ struct bfq_group *bfqg; ++ struct bfq_entity *entity; ++ ++ bfqg = bfq_find_set_group(bfqd, blkcg); ++ ++ if (unlikely(!bfqg)) ++ bfqg = bfqd->root_group; ++ ++ if (async_bfqq) { ++ entity = &async_bfqq->entity; ++ ++ if (entity->sched_data != &bfqg->sched_data) { ++ bic_set_bfqq(bic, NULL, 0); ++ bfq_log_bfqq(bfqd, async_bfqq, ++ "%p %d", ++ async_bfqq, ++ async_bfqq->ref); ++ bfq_put_queue(async_bfqq); ++ } ++ } ++ ++ if (sync_bfqq) { ++ entity = &sync_bfqq->entity; ++ if (entity->sched_data != &bfqg->sched_data) ++ bfq_bfqq_move(bfqd, sync_bfqq, bfqg); ++ } ++ ++ return bfqg; ++} ++ ++static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct bfq_group *bfqg = NULL; ++ uint64_t serial_nr; ++ ++ rcu_read_lock(); ++ serial_nr = bio_blkcg(bio)->css.serial_nr; ++ ++ /* ++ * Check whether blkcg has changed. The condition may trigger ++ * spuriously on a newly created cic but there's no harm. ++ */ ++ if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) ++ goto out; ++ ++ bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); ++#ifdef BFQ_MQ ++ /* ++ * Update blkg_path for bfq_log_* functions. We cache this ++ * path, and update it here, for the following ++ * reasons. Operations on blkg objects in blk-cgroup are ++ * protected with the request_queue lock, and not with the ++ * lock that protects the instances of this scheduler ++ * (bfqd->lock). This exposes BFQ to the following sort of ++ * race. ++ * ++ * The blkg_lookup performed in bfq_get_queue, protected ++ * through rcu, may happen to return the address of a copy of ++ * the original blkg. If this is the case, then the ++ * bfqg_and_blkg_get performed in bfq_get_queue, to pin down ++ * the blkg, is useless: it does not prevent blk-cgroup code ++ * from destroying both the original blkg and all objects ++ * directly or indirectly referred by the copy of the ++ * blkg. ++ * ++ * On the bright side, destroy operations on a blkg invoke, as ++ * a first step, hooks of the scheduler associated with the ++ * blkg. And these hooks are executed with bfqd->lock held for ++ * BFQ. As a consequence, for any blkg associated with the ++ * request queue this instance of the scheduler is attached ++ * to, we are guaranteed that such a blkg is not destroyed, and ++ * that all the pointers it contains are consistent, while we ++ * are holding bfqd->lock. A blkg_lookup performed with ++ * bfqd->lock held then returns a fully consistent blkg, which ++ * remains consistent until this lock is held. ++ * ++ * Thanks to the last fact, and to the fact that: (1) bfqg has ++ * been obtained through a blkg_lookup in the above ++ * assignment, and (2) bfqd->lock is being held, here we can ++ * safely use the policy data for the involved blkg (i.e., the ++ * field bfqg->pd) to get to the blkg associated with bfqg, ++ * and then we can safely use any field of blkg. After we ++ * release bfqd->lock, even just getting blkg through this ++ * bfqg may cause dangling references to be traversed, as ++ * bfqg->pd may not exist any more. ++ * ++ * In view of the above facts, here we cache, in the bfqg, any ++ * blkg data we may need for this bic, and for its associated ++ * bfq_queue. As of now, we need to cache only the path of the ++ * blkg, which is used in the bfq_log_* functions. ++ * ++ * Finally, note that bfqg itself needs to be protected from ++ * destruction on the blkg_free of the original blkg (which ++ * invokes bfq_pd_free). We use an additional private ++ * refcounter for bfqg, to let it disappear only after no ++ * bfq_queue refers to it any longer. ++ */ ++ blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path)); ++#endif ++ bic->blkcg_serial_nr = serial_nr; ++out: ++ rcu_read_unlock(); ++} ++ ++/** ++ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. ++ * @st: the service tree being flushed. ++ */ ++static void bfq_flush_idle_tree(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entity = st->first_idle; ++ ++ for (; entity ; entity = st->first_idle) ++ __bfq_deactivate_entity(entity, false); ++} ++ ++/** ++ * bfq_reparent_leaf_entity - move leaf entity to the root_group. ++ * @bfqd: the device data structure with the root group. ++ * @entity: the entity to move. ++ */ ++static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ BUG_ON(!bfqq); ++ bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); ++} ++ ++/** ++ * bfq_reparent_active_entities - move to the root group all active ++ * entities. ++ * @bfqd: the device data structure with the root group. ++ * @bfqg: the group to move from. ++ * @st: the service tree with the entities. ++ */ ++static void bfq_reparent_active_entities(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ struct bfq_service_tree *st) ++{ ++ struct rb_root *active = &st->active; ++ struct bfq_entity *entity = NULL; ++ ++ if (!RB_EMPTY_ROOT(&st->active)) ++ entity = bfq_entity_of(rb_first(active)); ++ ++ for (; entity ; entity = bfq_entity_of(rb_first(active))) ++ bfq_reparent_leaf_entity(bfqd, entity); ++ ++ if (bfqg->sched_data.in_service_entity) ++ bfq_reparent_leaf_entity(bfqd, ++ bfqg->sched_data.in_service_entity); ++} ++ ++/** ++ * bfq_pd_offline - deactivate the entity associated with @pd, ++ * and reparent its children entities. ++ * @pd: descriptor of the policy going offline. ++ * ++ * blkio already grabs the queue_lock for us, so no need to use ++ * RCU-based magic ++ */ ++static void bfq_pd_offline(struct blkg_policy_data *pd) ++{ ++ struct bfq_service_tree *st; ++ struct bfq_group *bfqg; ++ struct bfq_data *bfqd; ++ struct bfq_entity *entity; ++#ifdef BFQ_MQ ++ unsigned long flags; ++#endif ++ int i; ++ ++ BUG_ON(!pd); ++ bfqg = pd_to_bfqg(pd); ++ BUG_ON(!bfqg); ++ bfqd = bfqg->bfqd; ++ BUG_ON(bfqd && !bfqd->root_group); ++ ++ entity = bfqg->my_entity; ++ ++#ifdef BFQ_MQ ++ spin_lock_irqsave(&bfqd->lock, flags); ++#endif ++ ++ if (!entity) /* root group */ ++ goto put_async_queues; ++ ++ /* ++ * Empty all service_trees belonging to this group before ++ * deactivating the group itself. ++ */ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { ++ BUG_ON(!bfqg->sched_data.service_tree); ++ st = bfqg->sched_data.service_tree + i; ++ /* ++ * The idle tree may still contain bfq_queues belonging ++ * to exited task because they never migrated to a different ++ * cgroup from the one being destroyed now. ++ */ ++ bfq_flush_idle_tree(st); ++ ++ /* ++ * It may happen that some queues are still active ++ * (busy) upon group destruction (if the corresponding ++ * processes have been forced to terminate). We move ++ * all the leaf entities corresponding to these queues ++ * to the root_group. ++ * Also, it may happen that the group has an entity ++ * in service, which is disconnected from the active ++ * tree: it must be moved, too. ++ * There is no need to put the sync queues, as the ++ * scheduler has taken no reference. ++ */ ++ bfq_reparent_active_entities(bfqd, bfqg, st); ++ BUG_ON(!RB_EMPTY_ROOT(&st->active)); ++ BUG_ON(!RB_EMPTY_ROOT(&st->idle)); ++ } ++ BUG_ON(bfqg->sched_data.next_in_service); ++ BUG_ON(bfqg->sched_data.in_service_entity); ++ ++ __bfq_deactivate_entity(entity, false); ++ ++put_async_queues: ++ bfq_put_async_queues(bfqd, bfqg); ++ ++#ifdef BFQ_MQ ++ spin_unlock_irqrestore(&bfqd->lock, flags); ++#endif ++ /* ++ * @blkg is going offline and will be ignored by ++ * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so ++ * that they don't get lost. If IOs complete after this point, the ++ * stats for them will be lost. Oh well... ++ */ ++ bfqg_stats_xfer_dead(bfqg); ++} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ struct blkcg_gq *blkg; ++ ++ list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { ++ struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ BUG_ON(!bfqg); ++ ++ bfq_end_wr_async_queues(bfqd, bfqg); ++ } ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++static int bfq_io_show_weight(struct seq_file *sf, void *v) ++{ ++ struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); ++ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ unsigned int val = 0; ++ ++ if (bfqgd) ++ val = bfqgd->weight; ++ ++ seq_printf(sf, "%u\n", val); ++ ++ return 0; ++} ++ ++static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, ++ struct cftype *cftype, ++ u64 val) ++{ ++ struct blkcg *blkcg = css_to_blkcg(css); ++ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ struct blkcg_gq *blkg; ++ int ret = -ERANGE; ++ ++ if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) ++ return ret; ++ ++ ret = 0; ++ spin_lock_irq(&blkcg->lock); ++ bfqgd->weight = (unsigned short)val; ++ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { ++ struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ ++ if (!bfqg) ++ continue; ++ /* ++ * Setting the prio_changed flag of the entity ++ * to 1 with new_weight == weight would re-set ++ * the value of the weight to its ioprio mapping. ++ * Set the flag only if necessary. ++ */ ++ if ((unsigned short)val != bfqg->entity.new_weight) { ++ bfqg->entity.new_weight = (unsigned short)val; ++ /* ++ * Make sure that the above new value has been ++ * stored in bfqg->entity.new_weight before ++ * setting the prio_changed flag. In fact, ++ * this flag may be read asynchronously (in ++ * critical sections protected by a different ++ * lock than that held here), and finding this ++ * flag set may cause the execution of the code ++ * for updating parameters whose value may ++ * depend also on bfqg->entity.new_weight (in ++ * __bfq_entity_update_weight_prio). ++ * This barrier makes sure that the new value ++ * of bfqg->entity.new_weight is correctly ++ * seen in that code. ++ */ ++ smp_wmb(); ++ bfqg->entity.prio_changed = 1; ++ } ++ } ++ spin_unlock_irq(&blkcg->lock); ++ ++ return ret; ++} ++ ++static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, ++ char *buf, size_t nbytes, ++ loff_t off) ++{ ++ u64 weight; ++ /* First unsigned long found in the file is used */ ++ int ret = kstrtoull(strim(buf), 0, &weight); ++ ++ if (ret) ++ return ret; ++ ++ ret = bfq_io_set_weight_legacy(of_css(of), NULL, weight); ++ return ret ?: nbytes; ++} ++ ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++static int bfqg_print_stat(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, ++ &blkcg_policy_bfq, seq_cft(sf)->private, false); ++ return 0; ++} ++ ++static int bfqg_print_rwstat(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, ++ &blkcg_policy_bfq, seq_cft(sf)->private, true); ++ return 0; ++} ++ ++static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), ++ &blkcg_policy_bfq, off); ++ return __blkg_prfill_u64(sf, pd, sum); ++} ++ ++static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), ++ &blkcg_policy_bfq, ++ off); ++ return __blkg_prfill_rwstat(sf, pd, &sum); ++} ++ ++static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_stat_recursive, &blkcg_policy_bfq, ++ seq_cft(sf)->private, false); ++ return 0; ++} ++ ++static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, ++ seq_cft(sf)->private, true); ++ return 0; ++} ++ ++static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, ++ int off) ++{ ++ u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); ++ ++ return __blkg_prfill_u64(sf, pd, sum >> 9); ++} ++ ++static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); ++ return 0; ++} ++ ++static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, ++ offsetof(struct blkcg_gq, stat_bytes)); ++ u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + ++ atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); ++ ++ return __blkg_prfill_u64(sf, pd, sum >> 9); ++} ++ ++static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, ++ false); ++ return 0; ++} ++ ++ ++static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); ++ u64 v = 0; ++ ++ if (samples) { ++ v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); ++ v = div64_u64(v, samples); ++ } ++ __blkg_prfill_u64(sf, pd, v); ++ return 0; ++} ++ ++/* print avg_queue_size */ ++static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, ++ 0, false); ++ return 0; ++} ++#endif /* CONFIG_DEBUG_BLK_CGROUP */ ++ ++static struct bfq_group * ++bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) ++{ ++ int ret; ++ ++ ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); ++ if (ret) ++ return NULL; ++ ++ return blkg_to_bfqg(bfqd->queue->root_blkg); ++} ++ ++#ifdef BFQ_MQ ++#define BFQ_CGROUP_FNAME(param) "bfq-mq."#param ++#else ++#define BFQ_CGROUP_FNAME(param) "bfq-sq."#param ++#endif ++ ++static struct cftype bfq_blkcg_legacy_files[] = { ++ { ++ .name = BFQ_CGROUP_FNAME(weight), ++ .flags = CFTYPE_NOT_ON_ROOT, ++ .seq_show = bfq_io_show_weight, ++ .write_u64 = bfq_io_set_weight_legacy, ++ }, ++ ++ /* statistics, covers only the tasks in the bfqg */ ++ { ++ .name = BFQ_CGROUP_FNAME(io_service_bytes), ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_bytes, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_serviced), ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_ios, ++ }, ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ { ++ .name = BFQ_CGROUP_FNAME(time), ++ .private = offsetof(struct bfq_group, stats.time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(sectors), ++ .seq_show = bfqg_print_stat_sectors, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_service_time), ++ .private = offsetof(struct bfq_group, stats.service_time), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_wait_time), ++ .private = offsetof(struct bfq_group, stats.wait_time), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_merged), ++ .private = offsetof(struct bfq_group, stats.merged), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_queued), ++ .private = offsetof(struct bfq_group, stats.queued), ++ .seq_show = bfqg_print_rwstat, ++ }, ++#endif /* CONFIG_DEBUG_BLK_CGROUP */ ++ ++ /* the same statictics which cover the bfqg and its descendants */ ++ { ++ .name = BFQ_CGROUP_FNAME(io_service_bytes_recursive), ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_bytes_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_serviced_recursive), ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_ios_recursive, ++ }, ++#ifdef CONFIG_DEBUG_BLK_CGROUP ++ { ++ .name = BFQ_CGROUP_FNAME(time_recursive), ++ .private = offsetof(struct bfq_group, stats.time), ++ .seq_show = bfqg_print_stat_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(sectors_recursive), ++ .seq_show = bfqg_print_stat_sectors_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_service_time_recursive), ++ .private = offsetof(struct bfq_group, stats.service_time), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_wait_time_recursive), ++ .private = offsetof(struct bfq_group, stats.wait_time), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_merged_recursive), ++ .private = offsetof(struct bfq_group, stats.merged), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(io_queued_recursive), ++ .private = offsetof(struct bfq_group, stats.queued), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(avg_queue_size), ++ .seq_show = bfqg_print_avg_queue_size, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(group_wait_time), ++ .private = offsetof(struct bfq_group, stats.group_wait_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(idle_time), ++ .private = offsetof(struct bfq_group, stats.idle_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(empty_time), ++ .private = offsetof(struct bfq_group, stats.empty_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = BFQ_CGROUP_FNAME(dequeue), ++ .private = offsetof(struct bfq_group, stats.dequeue), ++ .seq_show = bfqg_print_stat, ++ }, ++#endif /* CONFIG_DEBUG_BLK_CGROUP */ ++ { } /* terminate */ ++}; ++ ++static struct cftype bfq_blkg_files[] = { ++ { ++ .name = BFQ_CGROUP_FNAME(weight), ++ .flags = CFTYPE_NOT_ON_ROOT, ++ .seq_show = bfq_io_show_weight, ++ .write = bfq_io_set_weight, ++ }, ++ {} /* terminate */ ++}; ++ ++#undef BFQ_CGROUP_FNAME ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_group *bfqg) {} ++ ++static void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) { ++ bfqq->ioprio = bfqq->new_ioprio; ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++ } ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, ++ struct blkcg *blkcg) ++{ ++ return bfqd->root_group; ++} ++ ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) ++{ ++ return bfqq->bfqd->root_group; ++} ++ ++static struct bfq_group * ++bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) ++{ ++ struct bfq_group *bfqg; ++ int i; ++ ++ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); ++ if (!bfqg) ++ return NULL; ++ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ ++ return bfqg; ++} ++#endif +diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c +new file mode 100644 +index 000000000000..fb7bb8f08b75 +--- /dev/null ++++ b/block/bfq-ioc.c +@@ -0,0 +1,36 @@ ++/* ++ * BFQ: I/O context handling. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it> ++ */ ++ ++/** ++ * icq_to_bic - convert iocontext queue structure to bfq_io_cq. ++ * @icq: the iocontext queue. ++ */ ++static struct bfq_io_cq *icq_to_bic(struct io_cq *icq) ++{ ++ /* bic->icq is the first member, %NULL will convert to %NULL */ ++ return container_of(icq, struct bfq_io_cq, icq); ++} ++ ++/** ++ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd. ++ * @bfqd: the lookup key. ++ * @ioc: the io_context of the process doing I/O. ++ * ++ * Queue lock must be held. ++ */ ++static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, ++ struct io_context *ioc) ++{ ++ if (ioc) ++ return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue)); ++ return NULL; ++} +diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c +new file mode 100644 +index 000000000000..47a49d9e6512 +--- /dev/null ++++ b/block/bfq-mq-iosched.c +@@ -0,0 +1,6548 @@ ++/* ++ * Budget Fair Queueing (BFQ) I/O scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org> ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ * ++ * BFQ is a proportional-share I/O scheduler, with some extra ++ * low-latency capabilities. BFQ also supports full hierarchical ++ * scheduling through cgroups. Next paragraphs provide an introduction ++ * on BFQ inner workings. Details on BFQ benefits and usage can be ++ * found in Documentation/block/bfq-iosched.txt. ++ * ++ * BFQ is a proportional-share storage-I/O scheduling algorithm based ++ * on the slice-by-slice service scheme of CFQ. But BFQ assigns ++ * budgets, measured in number of sectors, to processes instead of ++ * time slices. The device is not granted to the in-service process ++ * for a given time slice, but until it has exhausted its assigned ++ * budget. This change from the time to the service domain enables BFQ ++ * to distribute the device throughput among processes as desired, ++ * without any distortion due to throughput fluctuations, or to device ++ * internal queueing. BFQ uses an ad hoc internal scheduler, called ++ * B-WF2Q+, to schedule processes according to their budgets. More ++ * precisely, BFQ schedules queues associated with processes. Thanks to ++ * the accurate policy of B-WF2Q+, BFQ can afford to assign high ++ * budgets to I/O-bound processes issuing sequential requests (to ++ * boost the throughput), and yet guarantee a low latency to ++ * interactive and soft real-time applications. ++ * ++ * In particular, BFQ schedules I/O so as to achieve the latter goal-- ++ * low latency for interactive and soft real-time applications--if the ++ * low_latency parameter is set (default configuration). To this ++ * purpose, BFQ constantly tries to detect whether the I/O requests in ++ * a bfq_queue come from an interactive or a soft real-time ++ * application. For brevity, in these cases, the queue is said to be ++ * interactive or soft real-time. In both cases, BFQ privileges the ++ * service of the queue, over that of non-interactive and ++ * non-soft-real-time queues. This privileging is performed, mainly, ++ * by raising the weight of the queue. So, for brevity, we call just ++ * weight-raising periods the time periods during which a queue is ++ * privileged, because deemed interactive or soft real-time. ++ * ++ * The detection of soft real-time queues/applications is described in ++ * detail in the comments on the function ++ * bfq_bfqq_softrt_next_start. On the other hand, the detection of an ++ * interactive queue works as follows: a queue is deemed interactive ++ * if it is constantly non empty only for a limited time interval, ++ * after which it does become empty. The queue may be deemed ++ * interactive again (for a limited time), if it restarts being ++ * constantly non empty, provided that this happens only after the ++ * queue has remained empty for a given minimum idle time. ++ * ++ * By default, BFQ computes automatically the above maximum time ++ * interval, i.e., the time interval after which a constantly ++ * non-empty queue stops being deemed interactive. Since a queue is ++ * weight-raised while it is deemed interactive, this maximum time ++ * interval happens to coincide with the (maximum) duration of the ++ * weight-raising for interactive queues. ++ * ++ * NOTE: if the main or only goal, with a given device, is to achieve ++ * the maximum-possible throughput at all times, then do switch off ++ * all low-latency heuristics for that device, by setting low_latency ++ * to 0. ++ * ++ * BFQ is described in [1], where also a reference to the initial, ++ * more theoretical paper on BFQ can be found. The interested reader ++ * can find in the latter paper full details on the main algorithm, as ++ * well as formulas of the guarantees and formal proofs of all the ++ * properties. With respect to the version of BFQ presented in these ++ * papers, this implementation adds a few more heuristics, such as the ++ * one that guarantees a low latency to soft real-time applications, ++ * and a hierarchical extension based on H-WF2Q+. ++ * ++ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with ++ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N) ++ * complexity derives from the one introduced with EEVDF in [3]. ++ * ++ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O ++ * Scheduler", Proceedings of the First Workshop on Mobile System ++ * Technologies (MST-2015), May 2015. ++ * http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf ++ * ++ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf ++ * ++ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing ++ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689, ++ * Oct 1997. ++ * ++ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz ++ * ++ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline ++ * First: A Flexible and Accurate Mechanism for Proportional Share ++ * Resource Allocation,'' technical report. ++ * ++ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf ++ */ ++#include <linux/module.h> ++#include <linux/slab.h> ++#include <linux/blkdev.h> ++#include <linux/cgroup.h> ++#include <linux/elevator.h> ++#include <linux/jiffies.h> ++#include <linux/rbtree.h> ++#include <linux/ioprio.h> ++#include <linux/sbitmap.h> ++#include <linux/delay.h> ++ ++#include "blk.h" ++#include "blk-mq.h" ++#include "blk-mq-tag.h" ++#include "blk-mq-sched.h" ++#include "bfq-mq.h" ++#include "blk-wbt.h" ++ ++/* Expiration time of sync (0) and async (1) requests, in ns. */ ++static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 }; ++ ++/* Maximum backwards seek, in KiB. */ ++static const int bfq_back_max = (16 * 1024); ++ ++/* Penalty of a backwards seek, in number of sectors. */ ++static const int bfq_back_penalty = 2; ++ ++/* Idling period duration, in ns. */ ++static u32 bfq_slice_idle = (NSEC_PER_SEC / 125); ++ ++/* Minimum number of assigned budgets for which stats are safe to compute. */ ++static const int bfq_stats_min_budgets = 194; ++ ++/* Default maximum budget values, in sectors and number of requests. */ ++static const int bfq_default_max_budget = (16 * 1024); ++ ++/* ++ * When a sync request is dispatched, the queue that contains that ++ * request, and all the ancestor entities of that queue, are charged ++ * with the number of sectors of the request. In constrast, if the ++ * request is async, then the queue and its ancestor entities are ++ * charged with the number of sectors of the request, multiplied by ++ * the factor below. This throttles the bandwidth for async I/O, ++ * w.r.t. to sync I/O, and it is done to counter the tendency of async ++ * writes to steal I/O throughput to reads. ++ * ++ * The current value of this parameter is the result of a tuning with ++ * several hardware and software configurations. We tried to find the ++ * lowest value for which writes do not cause noticeable problems to ++ * reads. In fact, the lower this parameter, the stabler I/O control, ++ * in the following respect. The lower this parameter is, the less ++ * the bandwidth enjoyed by a group decreases ++ * - when the group does writes, w.r.t. to when it does reads; ++ * - when other groups do reads, w.r.t. to when they do writes. ++ */ ++static const int bfq_async_charge_factor = 3; ++ ++/* Default timeout values, in jiffies, approximating CFQ defaults. */ ++static const int bfq_timeout = (HZ / 8); ++ ++/* ++ * Time limit for merging (see comments in bfq_setup_cooperator). Set ++ * to the slowest value that, in our tests, proved to be effective in ++ * removing false positives, while not causing true positives to miss ++ * queue merging. ++ * ++ * As can be deduced from the low time limit below, queue merging, if ++ * successful, happens at the very beggining of the I/O of the involved ++ * cooperating processes, as a consequence of the arrival of the very ++ * first requests from each cooperator. After that, there is very ++ * little chance to find cooperators. ++ */ ++static const unsigned long bfq_merge_time_limit = HZ/10; ++ ++#define MAX_LENGTH_REASON_NAME 25 ++ ++static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE", ++"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS", ++"PREEMPTED"}; ++ ++static struct kmem_cache *bfq_pool; ++ ++/* Below this threshold (in ns), we consider thinktime immediate. */ ++#define BFQ_MIN_TT (2 * NSEC_PER_MSEC) ++ ++/* hw_tag detection: parallel requests threshold and min samples needed. */ ++#define BFQ_HW_QUEUE_THRESHOLD 3 ++#define BFQ_HW_QUEUE_SAMPLES 32 ++ ++#define BFQQ_SEEK_THR (sector_t)(8 * 100) ++#define BFQQ_SECT_THR_NONROT (sector_t)(2 * 32) ++#define BFQ_RQ_SEEKY(bfqd, last_pos, rq) \ ++ (get_sdist(last_pos, rq) > \ ++ BFQQ_SEEK_THR && \ ++ (!blk_queue_nonrot(bfqd->queue) || \ ++ blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT)) ++#define BFQQ_CLOSE_THR (sector_t)(8 * 1024) ++#define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 19) ++ ++/* Min number of samples required to perform peak-rate update */ ++#define BFQ_RATE_MIN_SAMPLES 32 ++/* Min observation time interval required to perform a peak-rate update (ns) */ ++#define BFQ_RATE_MIN_INTERVAL (300*NSEC_PER_MSEC) ++/* Target observation time interval for a peak-rate update (ns) */ ++#define BFQ_RATE_REF_INTERVAL NSEC_PER_SEC ++ ++/* ++ * Shift used for peak-rate fixed precision calculations. ++ * With ++ * - the current shift: 16 positions ++ * - the current type used to store rate: u32 ++ * - the current unit of measure for rate: [sectors/usec], or, more precisely, ++ * [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift, ++ * the range of rates that can be stored is ++ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec = ++ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec = ++ * [15, 65G] sectors/sec ++ * Which, assuming a sector size of 512B, corresponds to a range of ++ * [7.5K, 33T] B/sec ++ */ ++#define BFQ_RATE_SHIFT 16 ++ ++/* ++ * When configured for computing the duration of the weight-raising ++ * for interactive queues automatically (see the comments at the ++ * beginning of this file), BFQ does it using the following formula: ++ * duration = (ref_rate / r) * ref_wr_duration, ++ * where r is the peak rate of the device, and ref_rate and ++ * ref_wr_duration are two reference parameters. In particular, ++ * ref_rate is the peak rate of the reference storage device (see ++ * below), and ref_wr_duration is about the maximum time needed, with ++ * BFQ and while reading two files in parallel, to load typical large ++ * applications on the reference device (see the comments on ++ * max_service_from_wr below, for more details on how ref_wr_duration ++ * is obtained). In practice, the slower/faster the device at hand ++ * is, the more/less it takes to load applications with respect to the ++ * reference device. Accordingly, the longer/shorter BFQ grants ++ * weight raising to interactive applications. ++ * ++ * BFQ uses two different reference pairs (ref_rate, ref_wr_duration), ++ * depending on whether the device is rotational or non-rotational. ++ * ++ * In the following definitions, ref_rate[0] and ref_wr_duration[0] ++ * are the reference values for a rotational device, whereas ++ * ref_rate[1] and ref_wr_duration[1] are the reference values for a ++ * non-rotational device. The reference rates are not the actual peak ++ * rates of the devices used as a reference, but slightly lower ++ * values. The reason for using slightly lower values is that the ++ * peak-rate estimator tends to yield slightly lower values than the ++ * actual peak rate (it can yield the actual peak rate only if there ++ * is only one process doing I/O, and the process does sequential ++ * I/O). ++ * ++ * The reference peak rates are measured in sectors/usec, left-shifted ++ * by BFQ_RATE_SHIFT. ++ */ ++static int ref_rate[2] = {14000, 33000}; ++/* ++ * To improve readability, a conversion function is used to initialize ++ * the following array, which entails that the array can be ++ * initialized only in a function. ++ */ ++static int ref_wr_duration[2]; ++ ++/* ++ * BFQ uses the above-detailed, time-based weight-raising mechanism to ++ * privilege interactive tasks. This mechanism is vulnerable to the ++ * following false positives: I/O-bound applications that will go on ++ * doing I/O for much longer than the duration of weight ++ * raising. These applications have basically no benefit from being ++ * weight-raised at the beginning of their I/O. On the opposite end, ++ * while being weight-raised, these applications ++ * a) unjustly steal throughput to applications that may actually need ++ * low latency; ++ * b) make BFQ uselessly perform device idling; device idling results ++ * in loss of device throughput with most flash-based storage, and may ++ * increase latencies when used purposelessly. ++ * ++ * BFQ tries to reduce these problems, by adopting the following ++ * countermeasure. To introduce this countermeasure, we need first to ++ * finish explaining how the duration of weight-raising for ++ * interactive tasks is computed. ++ * ++ * For a bfq_queue deemed as interactive, the duration of weight ++ * raising is dynamically adjusted, as a function of the estimated ++ * peak rate of the device, so as to be equal to the time needed to ++ * execute the 'largest' interactive task we benchmarked so far. By ++ * largest task, we mean the task for which each involved process has ++ * to do more I/O than for any of the other tasks we benchmarked. This ++ * reference interactive task is the start-up of LibreOffice Writer, ++ * and in this task each process/bfq_queue needs to have at most ~110K ++ * sectors transferred. ++ * ++ * This last piece of information enables BFQ to reduce the actual ++ * duration of weight-raising for at least one class of I/O-bound ++ * applications: those doing sequential or quasi-sequential I/O. An ++ * example is file copy. In fact, once started, the main I/O-bound ++ * processes of these applications usually consume the above 110K ++ * sectors in much less time than the processes of an application that ++ * is starting, because these I/O-bound processes will greedily devote ++ * almost all their CPU cycles only to their target, ++ * throughput-friendly I/O operations. This is even more true if BFQ ++ * happens to be underestimating the device peak rate, and thus ++ * overestimating the duration of weight raising. But, according to ++ * our measurements, once transferred 110K sectors, these processes ++ * have no right to be weight-raised any longer. ++ * ++ * Basing on the last consideration, BFQ ends weight-raising for a ++ * bfq_queue if the latter happens to have received an amount of ++ * service at least equal to the following constant. The constant is ++ * set to slightly more than 110K, to have a minimum safety margin. ++ * ++ * This early ending of weight-raising reduces the amount of time ++ * during which interactive false positives cause the two problems ++ * described at the beginning of these comments. ++ */ ++static const unsigned long max_service_from_wr = 120000; ++ ++#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ ++ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) ++ ++#define RQ_BIC(rq) icq_to_bic((rq)->elv.priv[0]) ++#define RQ_BFQQ(rq) ((rq)->elv.priv[1]) ++ ++/** ++ * icq_to_bic - convert iocontext queue structure to bfq_io_cq. ++ * @icq: the iocontext queue. ++ */ ++static struct bfq_io_cq *icq_to_bic(struct io_cq *icq) ++{ ++ /* bic->icq is the first member, %NULL will convert to %NULL */ ++ return container_of(icq, struct bfq_io_cq, icq); ++} ++ ++/** ++ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd. ++ * @bfqd: the lookup key. ++ * @ioc: the io_context of the process doing I/O. ++ * @q: the request queue. ++ */ ++static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, ++ struct io_context *ioc, ++ struct request_queue *q) ++{ ++ if (ioc) { ++ unsigned long flags; ++ struct bfq_io_cq *icq; ++ ++ spin_lock_irqsave(q->queue_lock, flags); ++ icq = icq_to_bic(ioc_lookup_icq(ioc, q)); ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return icq; ++ } ++ ++ return NULL; ++} ++ ++/* ++ * Scheduler run of queue, if there are requests pending and no one in the ++ * driver that will restart queueing. ++ */ ++static void bfq_schedule_dispatch(struct bfq_data *bfqd) ++{ ++ if (bfqd->queued != 0) { ++ bfq_log(bfqd, ""); ++ blk_mq_run_hw_queues(bfqd->queue, true); ++ } ++} ++ ++#define BFQ_MQ ++#include "bfq-sched.c" ++#include "bfq-cgroup-included.c" ++ ++#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) ++#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) ++ ++#define bfq_sample_valid(samples) ((samples) > 80) ++ ++/* ++ * Lifted from AS - choose which of rq1 and rq2 that is best served now. ++ * We choose the request that is closesr to the head right now. Distance ++ * behind the head is penalized and only allowed to a certain extent. ++ */ ++static struct request *bfq_choose_req(struct bfq_data *bfqd, ++ struct request *rq1, ++ struct request *rq2, ++ sector_t last) ++{ ++ sector_t s1, s2, d1 = 0, d2 = 0; ++ unsigned long back_max; ++#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */ ++#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ ++ unsigned int wrap = 0; /* bit mask: requests behind the disk head? */ ++ ++ if (!rq1 || rq1 == rq2) ++ return rq2; ++ if (!rq2) ++ return rq1; ++ ++ if (rq_is_sync(rq1) && !rq_is_sync(rq2)) ++ return rq1; ++ else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) ++ return rq2; ++ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) ++ return rq1; ++ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META)) ++ return rq2; ++ ++ s1 = blk_rq_pos(rq1); ++ s2 = blk_rq_pos(rq2); ++ ++ /* ++ * By definition, 1KiB is 2 sectors. ++ */ ++ back_max = bfqd->bfq_back_max * 2; ++ ++ /* ++ * Strict one way elevator _except_ in the case where we allow ++ * short backward seeks which are biased as twice the cost of a ++ * similar forward seek. ++ */ ++ if (s1 >= last) ++ d1 = s1 - last; ++ else if (s1 + back_max >= last) ++ d1 = (last - s1) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ1_WRAP; ++ ++ if (s2 >= last) ++ d2 = s2 - last; ++ else if (s2 + back_max >= last) ++ d2 = (last - s2) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ2_WRAP; ++ ++ /* Found required data */ ++ ++ /* ++ * By doing switch() on the bit mask "wrap" we avoid having to ++ * check two variables for all permutations: --> faster! ++ */ ++ switch (wrap) { ++ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ ++ if (d1 < d2) ++ return rq1; ++ else if (d2 < d1) ++ return rq2; ++ ++ if (s1 >= s2) ++ return rq1; ++ else ++ return rq2; ++ ++ case BFQ_RQ2_WRAP: ++ return rq1; ++ case BFQ_RQ1_WRAP: ++ return rq2; ++ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */ ++ default: ++ /* ++ * Since both rqs are wrapped, ++ * start with the one that's further behind head ++ * (--> only *one* back seek required), ++ * since back seek takes more time than forward. ++ */ ++ if (s1 <= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++} ++ ++/* ++ * Async I/O can easily starve sync I/O (both sync reads and sync ++ * writes), by consuming all tags. Similarly, storms of sync writes, ++ * such as those that sync(2) may trigger, can starve sync reads. ++ * Limit depths of async I/O and sync writes so as to counter both ++ * problems. ++ */ ++static void bfq_limit_depth(unsigned int op, struct blk_mq_alloc_data *data) ++{ ++ struct bfq_data *bfqd = data->q->elevator->elevator_data; ++ ++ if (op_is_sync(op) && !op_is_write(op)) ++ return; ++ ++ data->shallow_depth = ++ bfqd->word_depths[!!bfqd->wr_busy_queues][op_is_sync(op)]; ++ ++ bfq_log(bfqd, "wr_busy %d sync %d depth %u", ++ bfqd->wr_busy_queues, op_is_sync(op), ++ data->shallow_depth); ++} ++ ++static struct bfq_queue * ++bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, ++ sector_t sector, struct rb_node **ret_parent, ++ struct rb_node ***rb_link) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *bfqq = NULL; ++ ++ parent = NULL; ++ p = &root->rb_node; ++ while (*p) { ++ struct rb_node **n; ++ ++ parent = *p; ++ bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ ++ /* ++ * Sort strictly based on sector. Smallest to the left, ++ * largest to the right. ++ */ ++ if (sector > blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_right; ++ else if (sector < blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_left; ++ else ++ break; ++ p = n; ++ bfqq = NULL; ++ } ++ ++ *ret_parent = parent; ++ if (rb_link) ++ *rb_link = p; ++ ++ bfq_log(bfqd, "%llu: returning %d", ++ (unsigned long long) sector, ++ bfqq ? bfqq->pid : 0); ++ ++ return bfqq; ++} ++ ++static bool bfq_too_late_for_merging(struct bfq_queue *bfqq) ++{ ++ return bfqq->service_from_backlogged > 0 && ++ time_is_before_jiffies(bfqq->first_IO_time + ++ bfq_merge_time_limit); ++} ++ ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *__bfqq; ++ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ ++ /* ++ * bfqq cannot be merged any longer (see comments in ++ * bfq_setup_cooperator): no point in adding bfqq into the ++ * position tree. ++ */ ++ if (bfq_too_late_for_merging(bfqq)) ++ return; ++ ++ if (bfq_class_idle(bfqq)) ++ return; ++ if (!bfqq->next_rq) ++ return; ++ ++ bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root, ++ blk_rq_pos(bfqq->next_rq), &parent, &p); ++ if (!__bfqq) { ++ rb_link_node(&bfqq->pos_node, parent, p); ++ rb_insert_color(&bfqq->pos_node, bfqq->pos_root); ++ } else ++ bfqq->pos_root = NULL; ++} ++ ++/* ++ * The following function returns true if every queue must receive the ++ * same share of the throughput (this condition is used when deciding ++ * whether idling may be disabled, see the comments in the function ++ * bfq_better_to_idle()). ++ * ++ * Such a scenario occurs when: ++ * 1) all active queues have the same weight, ++ * 2) all active queues belong to the same I/O-priority class, ++ * 3) all active groups at the same level in the groups tree have the same ++ * weight, ++ * 4) all active groups at the same level in the groups tree have the same ++ * number of children. ++ * ++ * Unfortunately, keeping the necessary state for evaluating exactly ++ * the last two symmetry sub-conditions above would be quite complex ++ * and time consuming. Therefore this function evaluates, instead, ++ * only the following stronger three sub-conditions, for which it is ++ * much easier to maintain the needed state: ++ * 1) all active queues have the same weight, ++ * 2) all active queues belong to the same I/O-priority class, ++ * 3) there are no active groups. ++ * In particular, the last condition is always true if hierarchical ++ * support or the cgroups interface are not enabled, thus no state ++ * needs to be maintained in this case. ++ */ ++static bool bfq_symmetric_scenario(struct bfq_data *bfqd) ++{ ++ /* ++ * For queue weights to differ, queue_weights_tree must contain ++ * at least two nodes. ++ */ ++ bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && ++ (bfqd->queue_weights_tree.rb_node->rb_left || ++ bfqd->queue_weights_tree.rb_node->rb_right); ++ ++ bool multiple_classes_busy = ++ (bfqd->busy_queues[0] && bfqd->busy_queues[1]) || ++ (bfqd->busy_queues[0] && bfqd->busy_queues[2]) || ++ (bfqd->busy_queues[1] && bfqd->busy_queues[2]); ++ ++ bfq_log(bfqd, "varied_queue_weights %d mul_classes %d", ++ varied_queue_weights, multiple_classes_busy); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ bfq_log(bfqd, "num_groups_with_pending_reqs %u", ++ bfqd->num_groups_with_pending_reqs); ++#endif ++ ++ return !(varied_queue_weights || multiple_classes_busy ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ || bfqd->num_groups_with_pending_reqs > 0 ++#endif ++ ); ++} ++ ++/* ++ * If the weight-counter tree passed as input contains no counter for ++ * the weight of the input queue, then add that counter; otherwise just ++ * increment the existing counter. ++ * ++ * Note that weight-counter trees contain few nodes in mostly symmetric ++ * scenarios. For example, if all queues have the same weight, then the ++ * weight-counter tree for the queues may contain at most one node. ++ * This holds even if low_latency is on, because weight-raised queues ++ * are not inserted in the tree. ++ * In most scenarios, the rate at which nodes are created/destroyed ++ * should be low too. ++ */ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct rb_node **new = &(root->rb_node), *parent = NULL; ++ ++ /* ++ * Do not insert if the queue is already associated with a ++ * counter, which happens if: ++ * 1) a request arrival has caused the queue to become both ++ * non-weight-raised, and hence change its weight, and ++ * backlogged; in this respect, each of the two events ++ * causes an invocation of this function, ++ * 2) this is the invocation of this function caused by the ++ * second event. This second invocation is actually useless, ++ * and we handle this fact by exiting immediately. More ++ * efficient or clearer solutions might possibly be adopted. ++ */ ++ if (bfqq->weight_counter) ++ return; ++ ++ while (*new) { ++ struct bfq_weight_counter *__counter = container_of(*new, ++ struct bfq_weight_counter, ++ weights_node); ++ parent = *new; ++ ++ if (entity->weight == __counter->weight) { ++ bfqq->weight_counter = __counter; ++ goto inc_counter; ++ } ++ if (entity->weight < __counter->weight) ++ new = &((*new)->rb_left); ++ else ++ new = &((*new)->rb_right); ++ } ++ ++ bfqq->weight_counter = kzalloc(sizeof(struct bfq_weight_counter), ++ GFP_ATOMIC); ++ ++ /* ++ * In the unlucky event of an allocation failure, we just ++ * exit. This will cause the weight of queue to not be ++ * considered in bfq_symmetric_scenario, which, in its turn, ++ * causes the scenario to be deemed wrongly symmetric in case ++ * bfqq's weight would have been the only weight making the ++ * scenario asymmetric. On the bright side, no unbalance will ++ * however occur when bfqq becomes inactive again (the ++ * invocation of this function is triggered by an activation ++ * of queue). In fact, bfq_weights_tree_remove does nothing ++ * if !bfqq->weight_counter. ++ */ ++ if (unlikely(!bfqq->weight_counter)) ++ return; ++ ++ bfqq->weight_counter->weight = entity->weight; ++ rb_link_node(&bfqq->weight_counter->weights_node, parent, new); ++ rb_insert_color(&bfqq->weight_counter->weights_node, root); ++ ++inc_counter: ++ bfqq->weight_counter->num_active++; ++ bfqq->ref++; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "refs %d weight %d symmetric %d", ++ bfqq->ref, ++ entity->weight, ++ bfq_symmetric_scenario(bfqd)); ++} ++ ++/* ++ * Decrement the weight counter associated with the queue, and, if the ++ * counter reaches 0, remove the counter from the tree. ++ * See the comments to the function bfq_weights_tree_add() for considerations ++ * about overhead. ++ */ ++static void __bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (!bfqq->weight_counter) ++ return; ++ ++ BUG_ON(RB_EMPTY_ROOT(root)); ++ BUG_ON(bfqq->weight_counter->weight != entity->weight); ++ ++ BUG_ON(!bfqq->weight_counter->num_active); ++ bfqq->weight_counter->num_active--; ++ ++ if (bfqq->weight_counter->num_active > 0) ++ goto reset_entity_pointer; ++ ++ rb_erase(&bfqq->weight_counter->weights_node, root); ++ kfree(bfqq->weight_counter); ++ ++reset_entity_pointer: ++ bfqq->weight_counter = NULL; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "refs %d weight %d symmetric %d", ++ bfqq->ref, ++ entity->weight, ++ bfq_symmetric_scenario(bfqd)); ++ bfq_put_queue(bfqq); ++} ++ ++/* ++ * Invoke __bfq_weights_tree_remove on bfqq and decrement the number ++ * of active groups for each queue's inactive parent entity. ++ */ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = bfqq->entity.parent; ++ ++ for_each_entity(entity) { ++ struct bfq_sched_data *sd = entity->my_sched_data; ++ ++ BUG_ON(entity->sched_data == NULL); /* ++ * It would mean ++ * that this is ++ * the root group. ++ */ ++ ++ if (sd->next_in_service || sd->in_service_entity) { ++ BUG_ON(!entity->in_groups_with_pending_reqs); ++ /* ++ * entity is still active, because either ++ * next_in_service or in_service_entity is not ++ * NULL (see the comments on the definition of ++ * next_in_service for details on why ++ * in_service_entity must be checked too). ++ * ++ * As a consequence, its parent entities are ++ * active as well, and thus this loop must ++ * stop here. ++ */ ++ break; ++ } ++ ++ BUG_ON(!bfqd->num_groups_with_pending_reqs && ++ entity->in_groups_with_pending_reqs); ++ /* ++ * The decrement of num_groups_with_pending_reqs is ++ * not performed immediately upon the deactivation of ++ * entity, but it is delayed to when it also happens ++ * that the first leaf descendant bfqq of entity gets ++ * all its pending requests completed. The following ++ * instructions perform this delayed decrement, if ++ * needed. See the comments on ++ * num_groups_with_pending_reqs for details. ++ */ ++ if (entity->in_groups_with_pending_reqs) { ++ entity->in_groups_with_pending_reqs = false; ++ bfqd->num_groups_with_pending_reqs--; ++ } ++ bfq_log_bfqq(bfqd, bfqq, "num_groups_with_pending_reqs %u", ++ bfqd->num_groups_with_pending_reqs); ++ } ++ ++ /* ++ * Next function is invoked last, because it causes bfqq to be ++ * freed if the following holds: bfqq is not in service and ++ * has no dispatched request. DO NOT use bfqq after the next ++ * function invocation. ++ */ ++ __bfq_weights_tree_remove(bfqd, bfqq, ++ &bfqd->queue_weights_tree); ++} ++ ++/* ++ * Return expired entry, or NULL to just start from scratch in rbtree. ++ */ ++static struct request *bfq_check_fifo(struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct request *rq; ++ ++ if (bfq_bfqq_fifo_expire(bfqq)) ++ return NULL; ++ ++ bfq_mark_bfqq_fifo_expire(bfqq); ++ ++ rq = rq_entry_fifo(bfqq->fifo.next); ++ ++ if (rq == last || ktime_get_ns() < rq->fifo_time) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq); ++ BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); ++ return rq; ++} ++ ++static struct request *bfq_find_next_rq(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct rb_node *rbnext = rb_next(&last->rb_node); ++ struct rb_node *rbprev = rb_prev(&last->rb_node); ++ struct request *next, *prev = NULL; ++ ++ BUG_ON(list_empty(&bfqq->fifo)); ++ ++ /* Follow expired path, else get first next available. */ ++ next = bfq_check_fifo(bfqq, last); ++ if (next) { ++ BUG_ON(next == last); ++ return next; ++ } ++ ++ BUG_ON(RB_EMPTY_NODE(&last->rb_node)); ++ ++ if (rbprev) ++ prev = rb_entry_rq(rbprev); ++ ++ if (rbnext) ++ next = rb_entry_rq(rbnext); ++ else { ++ rbnext = rb_first(&bfqq->sort_list); ++ if (rbnext && rbnext != &last->rb_node) ++ next = rb_entry_rq(rbnext); ++ } ++ ++ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last)); ++} ++ ++/* see the definition of bfq_async_charge_factor for details */ ++static unsigned long bfq_serv_to_charge(struct request *rq, ++ struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1 || ++ !bfq_symmetric_scenario(bfqq->bfqd)) ++ return blk_rq_sectors(rq); ++ ++ return blk_rq_sectors(rq) * bfq_async_charge_factor; ++} ++ ++/** ++ * bfq_updated_next_req - update the queue after a new next_rq selection. ++ * @bfqd: the device data the queue belongs to. ++ * @bfqq: the queue to update. ++ * ++ * If the first request of a queue changes we make sure that the queue ++ * has enough budget to serve at least its first request (if the ++ * request has grown). We do this because if the queue has not enough ++ * budget for its first request, it has to go through two dispatch ++ * rounds to actually get it dispatched. ++ */ ++static void bfq_updated_next_req(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct request *next_rq = bfqq->next_rq; ++ unsigned long new_budget; ++ ++ if (!next_rq) ++ return; ++ ++ if (bfqq == bfqd->in_service_queue) ++ /* ++ * In order not to break guarantees, budgets cannot be ++ * changed after an entity has been selected. ++ */ ++ return; ++ ++ BUG_ON(entity->tree != &st->active); ++ BUG_ON(entity == entity->sched_data->in_service_entity); ++ ++ new_budget = max_t(unsigned long, ++ max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)), ++ entity->service); ++ if (entity->budget != new_budget) { ++ entity->budget = new_budget; ++ bfq_log_bfqq(bfqd, bfqq, "new budget %lu", ++ new_budget); ++ bfq_requeue_bfqq(bfqd, bfqq, false); ++ } ++} ++ ++static unsigned int bfq_wr_duration(struct bfq_data *bfqd) ++{ ++ u64 dur; ++ ++ if (bfqd->bfq_wr_max_time > 0) ++ return bfqd->bfq_wr_max_time; ++ ++ dur = bfqd->rate_dur_prod; ++ do_div(dur, bfqd->peak_rate); ++ ++ /* ++ * Limit duration between 3 and 25 seconds. The upper limit ++ * has been conservatively set after the following worst case: ++ * on a QEMU/KVM virtual machine ++ * - running in a slow PC ++ * - with a virtual disk stacked on a slow low-end 5400rpm HDD ++ * - serving a heavy I/O workload, such as the sequential reading ++ * of several files ++ * mplayer took 23 seconds to start, if constantly weight-raised. ++ * ++ * As for higher values than that accomodating the above bad ++ * scenario, tests show that higher values would often yield ++ * the opposite of the desired result, i.e., would worsen ++ * responsiveness by allowing non-interactive applications to ++ * preserve weight raising for too long. ++ * ++ * On the other end, lower values than 3 seconds make it ++ * difficult for most interactive tasks to complete their jobs ++ * before weight-raising finishes. ++ */ ++ return clamp_val(dur, msecs_to_jiffies(3000), msecs_to_jiffies(25000)); ++} ++ ++/* switch back from soft real-time to interactive weight raising */ ++static void switch_back_to_interactive_wr(struct bfq_queue *bfqq, ++ struct bfq_data *bfqd) ++{ ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt; ++} ++ ++static void ++bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, bool bfq_already_existing) ++{ ++ unsigned int old_wr_coeff; ++ bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq); ++ ++ if (bic->saved_has_short_ttime) ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ else ++ bfq_clear_bfqq_has_short_ttime(bfqq); ++ ++ if (bic->saved_IO_bound) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ else ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (unlikely(busy)) ++ old_wr_coeff = bfqq->wr_coeff; ++ ++ bfqq->ttime = bic->saved_ttime; ++ bfqq->wr_coeff = bic->saved_wr_coeff; ++ bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt; ++ BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt)); ++ bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish; ++ bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time; ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "bic %p wr_coeff %d start_finish %lu max_time %lu", ++ bic, bfqq->wr_coeff, bfqq->last_wr_start_finish, ++ bfqq->wr_cur_max_time); ++ ++ if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) || ++ time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time))) { ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt + ++ bfq_wr_duration(bfqd))) { ++ switch_back_to_interactive_wr(bfqq, bfqd); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "switching back to interactive"); ++ } else { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "switching off wr (%lu + %lu < %lu)", ++ bfqq->last_wr_start_finish, bfqq->wr_cur_max_time, ++ jiffies); ++ } ++ } ++ ++ /* make sure weight will be updated, however we got here */ ++ bfqq->entity.prio_changed = 1; ++ ++ if (likely(!busy)) ++ return; ++ ++ if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) { ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd)); ++ } else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) { ++ bfqd->wr_busy_queues--; ++ BUG_ON(bfqd->wr_busy_queues < 0); ++ } ++} ++ ++static int bfqq_process_refs(struct bfq_queue *bfqq) ++{ ++ int process_refs, io_refs; ++ ++ lockdep_assert_held(&bfqq->bfqd->lock); ++ ++ io_refs = bfqq->allocated; ++ process_refs = bfqq->ref - io_refs - bfqq->entity.on_st - ++ (bfqq->weight_counter != NULL); ++ BUG_ON(process_refs < 0); ++ return process_refs; ++} ++ ++/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ ++static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *item; ++ struct hlist_node *n; ++ ++ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node) ++ hlist_del_init(&item->burst_list_node); ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++ bfqd->burst_size = 1; ++ bfqd->burst_parent_entity = bfqq->entity.parent; ++} ++ ++/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */ ++static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* Increment burst size to take into account also bfqq */ ++ bfqd->burst_size++; ++ ++ bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size); ++ ++ BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh); ++ ++ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) { ++ struct bfq_queue *pos, *bfqq_item; ++ struct hlist_node *n; ++ ++ /* ++ * Enough queues have been activated shortly after each ++ * other to consider this burst as large. ++ */ ++ bfqd->large_burst = true; ++ bfq_log_bfqq(bfqd, bfqq, "large burst started"); ++ ++ /* ++ * We can now mark all queues in the burst list as ++ * belonging to a large burst. ++ */ ++ hlist_for_each_entry(bfqq_item, &bfqd->burst_list, ++ burst_list_node) { ++ bfq_mark_bfqq_in_large_burst(bfqq_item); ++ bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst"); ++ } ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ bfq_log_bfqq(bfqd, bfqq, "marked in large burst"); ++ ++ /* ++ * From now on, and until the current burst finishes, any ++ * new queue being activated shortly after the last queue ++ * was inserted in the burst can be immediately marked as ++ * belonging to a large burst. So the burst list is not ++ * needed any more. Remove it. ++ */ ++ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list, ++ burst_list_node) ++ hlist_del_init(&pos->burst_list_node); ++ } else /* ++ * Burst not yet large: add bfqq to the burst list. Do ++ * not increment the ref counter for bfqq, because bfqq ++ * is removed from the burst list before freeing bfqq ++ * in put_queue. ++ */ ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++} ++ ++/* ++ * If many queues belonging to the same group happen to be created ++ * shortly after each other, then the processes associated with these ++ * queues have typically a common goal. In particular, bursts of queue ++ * creations are usually caused by services or applications that spawn ++ * many parallel threads/processes. Examples are systemd during boot, ++ * or git grep. To help these processes get their job done as soon as ++ * possible, it is usually better to not grant either weight-raising ++ * or device idling to their queues. ++ * ++ * In this comment we describe, firstly, the reasons why this fact ++ * holds, and, secondly, the next function, which implements the main ++ * steps needed to properly mark these queues so that they can then be ++ * treated in a different way. ++ * ++ * The above services or applications benefit mostly from a high ++ * throughput: the quicker the requests of the activated queues are ++ * cumulatively served, the sooner the target job of these queues gets ++ * completed. As a consequence, weight-raising any of these queues, ++ * which also implies idling the device for it, is almost always ++ * counterproductive. In most cases it just lowers throughput. ++ * ++ * On the other hand, a burst of queue creations may be caused also by ++ * the start of an application that does not consist of a lot of ++ * parallel I/O-bound threads. In fact, with a complex application, ++ * several short processes may need to be executed to start-up the ++ * application. In this respect, to start an application as quickly as ++ * possible, the best thing to do is in any case to privilege the I/O ++ * related to the application with respect to all other ++ * I/O. Therefore, the best strategy to start as quickly as possible ++ * an application that causes a burst of queue creations is to ++ * weight-raise all the queues created during the burst. This is the ++ * exact opposite of the best strategy for the other type of bursts. ++ * ++ * In the end, to take the best action for each of the two cases, the ++ * two types of bursts need to be distinguished. Fortunately, this ++ * seems relatively easy, by looking at the sizes of the bursts. In ++ * particular, we found a threshold such that only bursts with a ++ * larger size than that threshold are apparently caused by ++ * services or commands such as systemd or git grep. For brevity, ++ * hereafter we call just 'large' these bursts. BFQ *does not* ++ * weight-raise queues whose creation occurs in a large burst. In ++ * addition, for each of these queues BFQ performs or does not perform ++ * idling depending on which choice boosts the throughput more. The ++ * exact choice depends on the device and request pattern at ++ * hand. ++ * ++ * Unfortunately, false positives may occur while an interactive task ++ * is starting (e.g., an application is being started). The ++ * consequence is that the queues associated with the task do not ++ * enjoy weight raising as expected. Fortunately these false positives ++ * are very rare. They typically occur if some service happens to ++ * start doing I/O exactly when the interactive task starts. ++ * ++ * Turning back to the next function, it implements all the steps ++ * needed to detect the occurrence of a large burst and to properly ++ * mark all the queues belonging to it (so that they can then be ++ * treated in a different way). This goal is achieved by maintaining a ++ * "burst list" that holds, temporarily, the queues that belong to the ++ * burst in progress. The list is then used to mark these queues as ++ * belonging to a large burst if the burst does become large. The main ++ * steps are the following. ++ * ++ * . when the very first queue is created, the queue is inserted into the ++ * list (as it could be the first queue in a possible burst) ++ * ++ * . if the current burst has not yet become large, and a queue Q that does ++ * not yet belong to the burst is activated shortly after the last time ++ * at which a new queue entered the burst list, then the function appends ++ * Q to the burst list ++ * ++ * . if, as a consequence of the previous step, the burst size reaches ++ * the large-burst threshold, then ++ * ++ * . all the queues in the burst list are marked as belonging to a ++ * large burst ++ * ++ * . the burst list is deleted; in fact, the burst list already served ++ * its purpose (keeping temporarily track of the queues in a burst, ++ * so as to be able to mark them as belonging to a large burst in the ++ * previous sub-step), and now is not needed any more ++ * ++ * . the device enters a large-burst mode ++ * ++ * . if a queue Q that does not belong to the burst is created while ++ * the device is in large-burst mode and shortly after the last time ++ * at which a queue either entered the burst list or was marked as ++ * belonging to the current large burst, then Q is immediately marked ++ * as belonging to a large burst. ++ * ++ * . if a queue Q that does not belong to the burst is created a while ++ * later, i.e., not shortly after, than the last time at which a queue ++ * either entered the burst list or was marked as belonging to the ++ * current large burst, then the current burst is deemed as finished and: ++ * ++ * . the large-burst mode is reset if set ++ * ++ * . the burst list is emptied ++ * ++ * . Q is inserted in the burst list, as Q may be the first queue ++ * in a possible new burst (then the burst list contains just Q ++ * after this step). ++ */ ++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq is already in the burst list or is part of a large ++ * burst, or finally has just been split, then there is ++ * nothing else to do. ++ */ ++ if (!hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq) || ++ time_is_after_eq_jiffies(bfqq->split_time + ++ msecs_to_jiffies(10))) ++ return; ++ ++ /* ++ * If bfqq's creation happens late enough, or bfqq belongs to ++ * a different group than the burst group, then the current ++ * burst is finished, and related data structures must be ++ * reset. ++ * ++ * In this respect, consider the special case where bfqq is ++ * the very first queue created after BFQ is selected for this ++ * device. In this case, last_ins_in_burst and ++ * burst_parent_entity are not yet significant when we get ++ * here. But it is easy to verify that, whether or not the ++ * following condition is true, bfqq will end up being ++ * inserted into the burst list. In particular the list will ++ * happen to contain only bfqq. And this is exactly what has ++ * to happen, as bfqq may be the first queue of the first ++ * burst. ++ */ ++ if (time_is_before_jiffies(bfqd->last_ins_in_burst + ++ bfqd->bfq_burst_interval) || ++ bfqq->entity.parent != bfqd->burst_parent_entity) { ++ bfqd->large_burst = false; ++ bfq_reset_burst_list(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "late activation or different group"); ++ goto end; ++ } ++ ++ /* ++ * If we get here, then bfqq is being activated shortly after the ++ * last queue. So, if the current burst is also large, we can mark ++ * bfqq as belonging to this large burst immediately. ++ */ ++ if (bfqd->large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, "marked in burst"); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ goto end; ++ } ++ ++ /* ++ * If we get here, then a large-burst state has not yet been ++ * reached, but bfqq is being activated shortly after the last ++ * queue. Then we add bfqq to the burst. ++ */ ++ bfq_add_to_burst(bfqd, bfqq); ++end: ++ /* ++ * At this point, bfqq either has been added to the current ++ * burst or has caused the current burst to terminate and a ++ * possible new burst to start. In particular, in the second ++ * case, bfqq has become the first queue in the possible new ++ * burst. In both cases last_ins_in_burst needs to be moved ++ * forward. ++ */ ++ bfqd->last_ins_in_burst = jiffies; ++ ++} ++ ++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (entity->budget < entity->service) { ++ pr_crit("budget %d service %d\n", ++ entity->budget, entity->service); ++ BUG(); ++ } ++ return entity->budget - entity->service; ++} ++ ++/* ++ * If enough samples have been computed, return the current max budget ++ * stored in bfqd, which is dynamically updated according to the ++ * estimated disk peak rate; otherwise return the default max budget ++ */ ++static int bfq_max_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget; ++ else ++ return bfqd->bfq_max_budget; ++} ++ ++/* ++ * Return min budget, which is a fraction of the current or default ++ * max budget (trying with 1/32) ++ */ ++static int bfq_min_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget / 32; ++ else ++ return bfqd->bfq_max_budget / 32; ++} ++ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason); ++ ++/* ++ * The next function, invoked after the input queue bfqq switches from ++ * idle to busy, updates the budget of bfqq. The function also tells ++ * whether the in-service queue should be expired, by returning ++ * true. The purpose of expiring the in-service queue is to give bfqq ++ * the chance to possibly preempt the in-service queue, and the reason ++ * for preempting the in-service queue is to achieve one of the two ++ * goals below. ++ * ++ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has ++ * expired because it has remained idle. In particular, bfqq may have ++ * expired for one of the following two reasons: ++ * ++ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and ++ * did not make it to issue a new request before its last request ++ * was served; ++ * ++ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue ++ * a new request before the expiration of the idling-time. ++ * ++ * Even if bfqq has expired for one of the above reasons, the process ++ * associated with the queue may be however issuing requests greedily, ++ * and thus be sensitive to the bandwidth it receives (bfqq may have ++ * remained idle for other reasons: CPU high load, bfqq not enjoying ++ * idling, I/O throttling somewhere in the path from the process to ++ * the I/O scheduler, ...). But if, after every expiration for one of ++ * the above two reasons, bfqq has to wait for the service of at least ++ * one full budget of another queue before being served again, then ++ * bfqq is likely to get a much lower bandwidth or resource time than ++ * its reserved ones. To address this issue, two countermeasures need ++ * to be taken. ++ * ++ * First, the budget and the timestamps of bfqq need to be updated in ++ * a special way on bfqq reactivation: they need to be updated as if ++ * bfqq did not remain idle and did not expire. In fact, if they are ++ * computed as if bfqq expired and remained idle until reactivation, ++ * then the process associated with bfqq is treated as if, instead of ++ * being greedy, it stopped issuing requests when bfqq remained idle, ++ * and restarts issuing requests only on this reactivation. In other ++ * words, the scheduler does not help the process recover the "service ++ * hole" between bfqq expiration and reactivation. As a consequence, ++ * the process receives a lower bandwidth than its reserved one. In ++ * contrast, to recover this hole, the budget must be updated as if ++ * bfqq was not expired at all before this reactivation, i.e., it must ++ * be set to the value of the remaining budget when bfqq was ++ * expired. Along the same line, timestamps need to be assigned the ++ * value they had the last time bfqq was selected for service, i.e., ++ * before last expiration. Thus timestamps need to be back-shifted ++ * with respect to their normal computation (see [1] for more details ++ * on this tricky aspect). ++ * ++ * Secondly, to allow the process to recover the hole, the in-service ++ * queue must be expired too, to give bfqq the chance to preempt it ++ * immediately. In fact, if bfqq has to wait for a full budget of the ++ * in-service queue to be completed, then it may become impossible to ++ * let the process recover the hole, even if the back-shifted ++ * timestamps of bfqq are lower than those of the in-service queue. If ++ * this happens for most or all of the holes, then the process may not ++ * receive its reserved bandwidth. In this respect, it is worth noting ++ * that, being the service of outstanding requests unpreemptible, a ++ * little fraction of the holes may however be unrecoverable, thereby ++ * causing a little loss of bandwidth. ++ * ++ * The last important point is detecting whether bfqq does need this ++ * bandwidth recovery. In this respect, the next function deems the ++ * process associated with bfqq greedy, and thus allows it to recover ++ * the hole, if: 1) the process is waiting for the arrival of a new ++ * request (which implies that bfqq expired for one of the above two ++ * reasons), and 2) such a request has arrived soon. The first ++ * condition is controlled through the flag non_blocking_wait_rq, ++ * while the second through the flag arrived_in_time. If both ++ * conditions hold, then the function computes the budget in the ++ * above-described special way, and signals that the in-service queue ++ * should be expired. Timestamp back-shifting is done later in ++ * __bfq_activate_entity. ++ * ++ * 2. Reduce latency. Even if timestamps are not backshifted to let ++ * the process associated with bfqq recover a service hole, bfqq may ++ * however happen to have, after being (re)activated, a lower finish ++ * timestamp than the in-service queue. That is, the next budget of ++ * bfqq may have to be completed before the one of the in-service ++ * queue. If this is the case, then preempting the in-service queue ++ * allows this goal to be achieved, apart from the unpreemptible, ++ * outstanding requests mentioned above. ++ * ++ * Unfortunately, regardless of which of the above two goals one wants ++ * to achieve, service trees need first to be updated to know whether ++ * the in-service queue must be preempted. To have service trees ++ * correctly updated, the in-service queue must be expired and ++ * rescheduled, and bfqq must be scheduled too. This is one of the ++ * most costly operations (in future versions, the scheduling ++ * mechanism may be re-designed in such a way to make it possible to ++ * know whether preemption is needed without needing to update service ++ * trees). In addition, queue preemptions almost always cause random ++ * I/O, and thus loss of throughput. Because of these facts, the next ++ * function adopts the following simple scheme to avoid both costly ++ * operations and too frequent preemptions: it requests the expiration ++ * of the in-service queue (unconditionally) only for queues that need ++ * to recover a hole, or that either are weight-raised or deserve to ++ * be weight-raised. ++ */ ++static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool arrived_in_time, ++ bool wr_or_deserves_wr) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ /* ++ * In the next compound condition, we check also whether there ++ * is some budget left, because otherwise there is no point in ++ * trying to go on serving bfqq with this same budget: bfqq ++ * would be expired immediately after being selected for ++ * service. This would only cause useless overhead. ++ */ ++ if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time && ++ bfq_bfqq_budget_left(bfqq) > 0) { ++ /* ++ * We do not clear the flag non_blocking_wait_rq here, as ++ * the latter is used in bfq_activate_bfqq to signal ++ * that timestamps need to be back-shifted (and is ++ * cleared right after). ++ */ ++ ++ /* ++ * In next assignment we rely on that either ++ * entity->service or entity->budget are not updated ++ * on expiration if bfqq is empty (see ++ * __bfq_bfqq_recalc_budget). Thus both quantities ++ * remain unchanged after such an expiration, and the ++ * following statement therefore assigns to ++ * entity->budget the remaining budget on such an ++ * expiration. ++ */ ++ BUG_ON(bfqq->max_budget < 0); ++ entity->budget = min_t(unsigned long, ++ bfq_bfqq_budget_left(bfqq), ++ bfqq->max_budget); ++ ++ BUG_ON(entity->budget < 0); ++ ++ /* ++ * At this point, we have used entity->service to get ++ * the budget left (needed for updating ++ * entity->budget). Thus we finally can, and have to, ++ * reset entity->service. The latter must be reset ++ * because bfqq would otherwise be charged again for ++ * the service it has received during its previous ++ * service slot(s). ++ */ ++ entity->service = 0; ++ ++ return true; ++ } ++ ++ /* ++ * We can finally complete expiration, by setting service to 0. ++ */ ++ entity->service = 0; ++ BUG_ON(bfqq->max_budget < 0); ++ entity->budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(bfqq->next_rq, bfqq)); ++ BUG_ON(entity->budget < 0); ++ ++ bfq_clear_bfqq_non_blocking_wait_rq(bfqq); ++ return wr_or_deserves_wr; ++} ++ ++/* ++ * Return the farthest past time instant according to jiffies ++ * macros. ++ */ ++static unsigned long bfq_smallest_from_now(void) ++{ ++ return jiffies - MAX_JIFFY_OFFSET; ++} ++ ++static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ unsigned int old_wr_coeff, ++ bool wr_or_deserves_wr, ++ bool interactive, ++ bool in_burst, ++ bool soft_rt) ++{ ++ if (old_wr_coeff == 1 && wr_or_deserves_wr) { ++ /* start a weight-raising period */ ++ if (interactive) { ++ bfqq->service_from_wr = 0; ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ } else { ++ /* ++ * No interactive weight raising in progress ++ * here: assign minus infinity to ++ * wr_start_at_switch_to_srt, to make sure ++ * that, at the end of the soft-real-time ++ * weight raising periods that is starting ++ * now, no interactive weight-raising period ++ * may be wrongly considered as still in ++ * progress (and thus actually started by ++ * mistake). ++ */ ++ bfqq->wr_start_at_switch_to_srt = ++ bfq_smallest_from_now(); ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff * ++ BFQ_SOFTRT_WEIGHT_FACTOR; ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ } ++ /* ++ * If needed, further reduce budget to make sure it is ++ * close to bfqq's backlog, so as to reduce the ++ * scheduling-error component due to a too large ++ * budget. Do not care about throughput consequences, ++ * but only about latency. Finally, do not assign a ++ * too small budget either, to avoid increasing ++ * latency by causing too frequent expirations. ++ */ ++ bfqq->entity.budget = min_t(unsigned long, ++ bfqq->entity.budget, ++ 2 * bfq_min_budget(bfqd)); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } else if (old_wr_coeff > 1) { ++ if (interactive) { /* update wr coeff and duration */ ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ } else if (in_burst) { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq-> ++ wr_cur_max_time)); ++ } else if (soft_rt) { ++ /* ++ * The application is now or still meeting the ++ * requirements for being deemed soft rt. We ++ * can then correctly and safely (re)charge ++ * the weight-raising duration for the ++ * application with the weight-raising ++ * duration for soft rt applications. ++ * ++ * In particular, doing this recharge now, i.e., ++ * before the weight-raising period for the ++ * application finishes, reduces the probability ++ * of the following negative scenario: ++ * 1) the weight of a soft rt application is ++ * raised at startup (as for any newly ++ * created application), ++ * 2) since the application is not interactive, ++ * at a certain time weight-raising is ++ * stopped for the application, ++ * 3) at that time the application happens to ++ * still have pending requests, and hence ++ * is destined to not have a chance to be ++ * deemed soft rt before these requests are ++ * completed (see the comments to the ++ * function bfq_bfqq_softrt_next_start() ++ * for details on soft rt detection), ++ * 4) these pending requests experience a high ++ * latency because the application is not ++ * weight-raised while they are pending. ++ */ ++ if (bfqq->wr_cur_max_time != ++ bfqd->bfq_wr_rt_max_time) { ++ bfqq->wr_start_at_switch_to_srt = ++ bfqq->last_wr_start_finish; ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff * ++ BFQ_SOFTRT_WEIGHT_FACTOR; ++ bfq_log_bfqq(bfqd, bfqq, ++ "switching to soft_rt wr"); ++ } else ++ bfq_log_bfqq(bfqd, bfqq, ++ "moving forward soft_rt wr duration"); ++ bfqq->last_wr_start_finish = jiffies; ++ } ++ } ++} ++ ++static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ return bfqq->dispatched == 0 && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ bfqd->bfq_wr_min_idle_time); ++} ++ ++static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ int old_wr_coeff, ++ struct request *rq, ++ bool *interactive) ++{ ++ bool soft_rt, in_burst, wr_or_deserves_wr, ++ bfqq_wants_to_preempt, ++ idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq), ++ /* ++ * See the comments on ++ * bfq_bfqq_update_budg_for_activation for ++ * details on the usage of the next variable. ++ */ ++ arrived_in_time = ktime_get_ns() <= ++ bfqq->ttime.last_end_request + ++ bfqd->bfq_slice_idle * 3; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request non-busy: " ++ "jiffies %lu, in_time %d, idle_long %d busyw %d " ++ "wr_coeff %u", ++ jiffies, arrived_in_time, ++ idle_for_long_time, ++ bfq_bfqq_non_blocking_wait_rq(bfqq), ++ old_wr_coeff); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ ++ /* ++ * bfqq deserves to be weight-raised if: ++ * - it is sync, ++ * - it does not belong to a large burst, ++ * - it has been idle for enough time or is soft real-time, ++ * - is linked to a bfq_io_cq (it is not shared in any sense) ++ */ ++ in_burst = bfq_bfqq_in_large_burst(bfqq); ++ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && ++ !in_burst && ++ time_is_before_jiffies(bfqq->soft_rt_next_start) && ++ bfqq->dispatched == 0; ++ *interactive = ++ !in_burst && ++ idle_for_long_time; ++ wr_or_deserves_wr = bfqd->low_latency && ++ (bfqq->wr_coeff > 1 || ++ (bfq_bfqq_sync(bfqq) && ++ bfqq->bic && (*interactive || soft_rt))); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request: " ++ "in_burst %d, " ++ "soft_rt %d (next %lu), inter %d, bic %p", ++ bfq_bfqq_in_large_burst(bfqq), soft_rt, ++ bfqq->soft_rt_next_start, ++ *interactive, ++ bfqq->bic); ++ ++ /* ++ * Using the last flag, update budget and check whether bfqq ++ * may want to preempt the in-service queue. ++ */ ++ bfqq_wants_to_preempt = ++ bfq_bfqq_update_budg_for_activation(bfqd, bfqq, ++ arrived_in_time, ++ wr_or_deserves_wr); ++ ++ /* ++ * If bfqq happened to be activated in a burst, but has been ++ * idle for much more than an interactive queue, then we ++ * assume that, in the overall I/O initiated in the burst, the ++ * I/O associated with bfqq is finished. So bfqq does not need ++ * to be treated as a queue belonging to a burst ++ * anymore. Accordingly, we reset bfqq's in_large_burst flag ++ * if set, and remove bfqq from the burst list if it's ++ * there. We do not decrement burst_size, because the fact ++ * that bfqq does not need to belong to the burst list any ++ * more does not invalidate the fact that bfqq was created in ++ * a burst. ++ */ ++ if (likely(!bfq_bfqq_just_created(bfqq)) && ++ idle_for_long_time && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ msecs_to_jiffies(10000))) { ++ hlist_del_init(&bfqq->burst_list_node); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ ++ bfq_clear_bfqq_just_created(bfqq); ++ ++ if (!bfq_bfqq_IO_bound(bfqq)) { ++ if (arrived_in_time) { ++ bfqq->requests_within_timer++; ++ if (bfqq->requests_within_timer >= ++ bfqd->bfq_requests_within_timer) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ } else ++ bfqq->requests_within_timer = 0; ++ bfq_log_bfqq(bfqd, bfqq, "requests in time %d", ++ bfqq->requests_within_timer); ++ } ++ ++ if (bfqd->low_latency) { ++ if (unlikely(time_is_after_jiffies(bfqq->split_time))) ++ /* wraparound */ ++ bfqq->split_time = ++ jiffies - bfqd->bfq_wr_min_idle_time - 1; ++ ++ if (time_is_before_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) { ++ bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq, ++ old_wr_coeff, ++ wr_or_deserves_wr, ++ *interactive, ++ in_burst, ++ soft_rt); ++ ++ if (old_wr_coeff != bfqq->wr_coeff) ++ bfqq->entity.prio_changed = 1; ++ } ++ } ++ ++ bfqq->last_idle_bklogged = jiffies; ++ bfqq->service_from_backlogged = 0; ++ bfq_clear_bfqq_softrt_update(bfqq); ++ ++ bfq_add_bfqq_busy(bfqd, bfqq); ++ ++ /* ++ * Expire in-service queue only if preemption may be needed ++ * for guarantees. In this respect, the function ++ * next_queue_may_preempt just checks a simple, necessary ++ * condition, and not a sufficient condition based on ++ * timestamps. In fact, for the latter condition to be ++ * evaluated, timestamps would need first to be updated, and ++ * this operation is quite costly (see the comments on the ++ * function bfq_bfqq_update_budg_for_activation). ++ */ ++ if (bfqd->in_service_queue && bfqq_wants_to_preempt && ++ bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff && ++ next_queue_may_preempt(bfqd)) { ++ struct bfq_queue *in_serv = ++ bfqd->in_service_queue; ++ BUG_ON(in_serv == bfqq); ++ ++ bfq_bfqq_expire(bfqd, bfqd->in_service_queue, ++ false, BFQ_BFQQ_PREEMPTED); ++ } ++} ++ ++static void bfq_add_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *next_rq, *prev; ++ unsigned int old_wr_coeff = bfqq->wr_coeff; ++ bool interactive = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "size %u %s", ++ blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A"); ++ ++ if (bfqq->wr_coeff > 1) /* queue is being weight-raised */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ bfqq->queued[rq_is_sync(rq)]++; ++ bfqd->queued++; ++ ++ BUG_ON(!RQ_BFQQ(rq)); ++ BUG_ON(RQ_BFQQ(rq) != bfqq); ++ WARN_ON(blk_rq_sectors(rq) == 0); ++ ++ elv_rb_add(&bfqq->sort_list, rq); ++ ++ /* ++ * Check if this request is a better next-to-serve candidate. ++ */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); ++ BUG_ON(!next_rq); ++ BUG_ON(!RQ_BFQQ(next_rq)); ++ BUG_ON(RQ_BFQQ(next_rq) != bfqq); ++ bfqq->next_rq = next_rq; ++ ++ /* ++ * Adjust priority tree position, if next_rq changes. ++ */ ++ if (prev != bfqq->next_rq) ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ ++ if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */ ++ bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff, ++ rq, &interactive); ++ else { ++ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) && ++ time_is_before_jiffies( ++ bfqq->last_wr_start_finish + ++ bfqd->bfq_wr_min_inter_arr_async)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd)); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "non-idle wrais starting, " ++ "wr_max_time %u wr_busy %d", ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqd->wr_busy_queues); ++ } ++ if (prev != bfqq->next_rq) ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ /* ++ * Assign jiffies to last_wr_start_finish in the following ++ * cases: ++ * ++ * . if bfqq is not going to be weight-raised, because, for ++ * non weight-raised queues, last_wr_start_finish stores the ++ * arrival time of the last request; as of now, this piece ++ * of information is used only for deciding whether to ++ * weight-raise async queues ++ * ++ * . if bfqq is not weight-raised, because, if bfqq is now ++ * switching to weight-raised, then last_wr_start_finish ++ * stores the time when weight-raising starts ++ * ++ * . if bfqq is interactive, because, regardless of whether ++ * bfqq is currently weight-raised, the weight-raising ++ * period must start or restart (this case is considered ++ * separately because it is not detected by the above ++ * conditions, if bfqq is already weight-raised) ++ * ++ * last_wr_start_finish has to be updated also if bfqq is soft ++ * real-time, because the weight-raising period is constantly ++ * restarted on idle-to-busy transitions for these queues, but ++ * this is already done in bfq_bfqq_handle_idle_busy_switch if ++ * needed. ++ */ ++ if (bfqd->low_latency && ++ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive)) ++ bfqq->last_wr_start_finish = jiffies; ++} ++ ++static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, ++ struct bio *bio, ++ struct request_queue *q) ++{ ++ struct bfq_queue *bfqq = bfqd->bio_bfqq; ++ ++ BUG_ON(!bfqd->bio_bfqq_set); ++ ++ if (bfqq) ++ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); ++ ++ return NULL; ++} ++ ++static sector_t get_sdist(sector_t last_pos, struct request *rq) ++{ ++ sector_t sdist = 0; ++ ++ if (last_pos) { ++ if (last_pos < blk_rq_pos(rq)) ++ sdist = blk_rq_pos(rq) - last_pos; ++ else ++ sdist = last_pos - blk_rq_pos(rq); ++ } ++ ++ return sdist; ++} ++ ++#if 0 /* Still not clear if we can do without next two functions */ ++static void bfq_activate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ bfqd->rq_in_driver++; ++} ++ ++static void bfq_deactivate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ BUG_ON(bfqd->rq_in_driver == 0); ++ bfqd->rq_in_driver--; ++} ++#endif ++ ++static void bfq_remove_request(struct request_queue *q, ++ struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ const int sync = rq_is_sync(rq); ++ ++ BUG_ON(bfqq->entity.service > bfqq->entity.budget); ++ ++ if (bfqq->next_rq == rq) { ++ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); ++ if (bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq)) { ++ pr_crit("no bfqq! for next rq %p bfqq %p\n", ++ bfqq->next_rq, bfqq); ++ } ++ ++ BUG_ON(bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq)); ++ if (bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq) { ++ pr_crit( ++ "wrong bfqq! for next rq %p, rq_bfqq %p bfqq %p\n", ++ bfqq->next_rq, RQ_BFQQ(bfqq->next_rq), bfqq); ++ } ++ BUG_ON(bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq); ++ ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ if (rq->queuelist.prev != &rq->queuelist) ++ list_del_init(&rq->queuelist); ++ BUG_ON(bfqq->queued[sync] == 0); ++ bfqq->queued[sync]--; ++ bfqd->queued--; ++ elv_rb_del(&bfqq->sort_list, rq); ++ ++ elv_rqhash_del(q, rq); ++ if (q->last_merge == rq) ++ q->last_merge = NULL; ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ bfqq->next_rq = NULL; ++ ++ BUG_ON(bfqq->entity.budget < 0); ++ ++ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) { ++ BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */ ++ bfq_del_bfqq_busy(bfqd, bfqq, false); ++ /* ++ * bfqq emptied. In normal operation, when ++ * bfqq is empty, bfqq->entity.service and ++ * bfqq->entity.budget must contain, ++ * respectively, the service received and the ++ * budget used last time bfqq emptied. These ++ * facts do not hold in this case, as at least ++ * this last removal occurred while bfqq is ++ * not in service. To avoid inconsistencies, ++ * reset both bfqq->entity.service and ++ * bfqq->entity.budget, if bfqq has still a ++ * process that may issue I/O requests to it. ++ */ ++ bfqq->entity.budget = bfqq->entity.service = 0; ++ } ++ ++ /* ++ * Remove queue from request-position tree as it is empty. ++ */ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ } else { ++ BUG_ON(!bfqq->next_rq); ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ ++ if (rq->cmd_flags & REQ_META) { ++ BUG_ON(bfqq->meta_pending == 0); ++ bfqq->meta_pending--; ++ } ++} ++ ++static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio) ++{ ++ struct request_queue *q = hctx->queue; ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct request *free = NULL; ++ /* ++ * bfq_bic_lookup grabs the queue_lock: invoke it now and ++ * store its return value for later use, to avoid nesting ++ * queue_lock inside the bfqd->lock. We assume that the bic ++ * returned by bfq_bic_lookup does not go away before ++ * bfqd->lock is taken. ++ */ ++ struct bfq_io_cq *bic = bfq_bic_lookup(bfqd, current->io_context, q); ++ bool ret; ++ ++ spin_lock_irq(&bfqd->lock); ++ ++ if (bic) ++ bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf)); ++ else ++ bfqd->bio_bfqq = NULL; ++ bfqd->bio_bic = bic; ++ /* Set next flag just for testing purposes */ ++ bfqd->bio_bfqq_set = true; ++ ++ ret = blk_mq_sched_try_merge(q, bio, &free); ++ ++ /* ++ * XXX Not yet freeing without lock held, to avoid an ++ * inconsistency with respect to the lock-protected invocation ++ * of blk_mq_sched_try_insert_merge in bfq_bio_merge. Waiting ++ * for clarifications from Jens. ++ */ ++ if (free) ++ blk_mq_free_request(free); ++ bfqd->bio_bfqq_set = false; ++ spin_unlock_irq(&bfqd->lock); ++ ++ return ret; ++} ++ ++static int bfq_request_merge(struct request_queue *q, struct request **req, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct request *__rq; ++ ++ __rq = bfq_find_rq_fmerge(bfqd, bio, q); ++ if (__rq && elv_bio_merge_ok(__rq, bio)) { ++ *req = __rq; ++ bfq_log(bfqd, "req %p", __rq); ++ ++ return ELEVATOR_FRONT_MERGE; ++ } ++ ++ return ELEVATOR_NO_MERGE; ++} ++ ++static struct bfq_queue *bfq_init_rq(struct request *rq); ++ ++static void bfq_request_merged(struct request_queue *q, struct request *req, ++ enum elv_merge type) ++{ ++ BUG_ON(req->rq_flags & RQF_DISP_LIST); ++ ++ if (type == ELEVATOR_FRONT_MERGE && ++ rb_prev(&req->rb_node) && ++ blk_rq_pos(req) < ++ blk_rq_pos(container_of(rb_prev(&req->rb_node), ++ struct request, rb_node))) { ++ struct bfq_queue *bfqq = bfq_init_rq(req); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *prev, *next_rq; ++ ++ /* Reposition request in its sort_list */ ++ elv_rb_del(&bfqq->sort_list, req); ++ BUG_ON(!RQ_BFQQ(req)); ++ BUG_ON(RQ_BFQQ(req) != bfqq); ++ elv_rb_add(&bfqq->sort_list, req); ++ ++ /* Choose next request to be served for bfqq */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, ++ bfqd->last_position); ++ BUG_ON(!next_rq); ++ ++ bfqq->next_rq = next_rq; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "req %p prev %p next_rq %p bfqq %p", ++ req, prev, next_rq, bfqq); ++ ++ /* ++ * If next_rq changes, update both the queue's budget to ++ * fit the new request and the queue's position in its ++ * rq_pos_tree. ++ */ ++ if (prev != bfqq->next_rq) { ++ bfq_updated_next_req(bfqd, bfqq); ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ } ++} ++ ++/* ++ * This function is called to notify the scheduler that the requests ++ * rq and 'next' have been merged, with 'next' going away. BFQ ++ * exploits this hook to address the following issue: if 'next' has a ++ * fifo_time lower that rq, then the fifo_time of rq must be set to ++ * the value of 'next', to not forget the greater age of 'next'. ++ * ++ * NOTE: in this function we assume that rq is in a bfq_queue, basing ++ * on that rq is picked from the hash table q->elevator->hash, which, ++ * in its turn, is filled only with I/O requests present in ++ * bfq_queues, while BFQ is in use for the request queue q. In fact, ++ * the function that fills this hash table (elv_rqhash_add) is called ++ * only by bfq_insert_request. ++ */ ++static void bfq_requests_merged(struct request_queue *q, struct request *rq, ++ struct request *next) ++{ ++ struct bfq_queue *bfqq = bfq_init_rq(rq), ++ *next_bfqq = bfq_init_rq(next); ++ ++ BUG_ON(!RQ_BFQQ(rq)); ++ BUG_ON(!RQ_BFQQ(next)); /* this does not imply next is in a bfqq */ ++ BUG_ON(rq->rq_flags & RQF_DISP_LIST); ++ BUG_ON(next->rq_flags & RQF_DISP_LIST); ++ ++ lockdep_assert_held(&bfqq->bfqd->lock); ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "rq %p next %p bfqq %p next_bfqq %p", ++ rq, next, bfqq, next_bfqq); ++ ++ /* ++ * If next and rq belong to the same bfq_queue and next is older ++ * than rq, then reposition rq in the fifo (by substituting next ++ * with rq). Otherwise, if next and rq belong to different ++ * bfq_queues, never reposition rq: in fact, we would have to ++ * reposition it with respect to next's position in its own fifo, ++ * which would most certainly be too expensive with respect to ++ * the benefits. ++ */ ++ if (bfqq == next_bfqq && ++ !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && ++ next->fifo_time < rq->fifo_time) { ++ list_del_init(&rq->queuelist); ++ list_replace_init(&next->queuelist, &rq->queuelist); ++ rq->fifo_time = next->fifo_time; ++ } ++ ++ if (bfqq->next_rq == next) ++ bfqq->next_rq = rq; ++ ++ bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); ++} ++ ++/* Must be called with bfqq != NULL */ ++static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) ++{ ++ BUG_ON(!bfqq); ++ ++ if (bfq_bfqq_busy(bfqq)) { ++ bfqq->bfqd->wr_busy_queues--; ++ BUG_ON(bfqq->bfqd->wr_busy_queues < 0); ++ } ++ bfqq->wr_coeff = 1; ++ bfqq->wr_cur_max_time = 0; ++ bfqq->last_wr_start_finish = jiffies; ++ /* ++ * Trigger a weight change on the next invocation of ++ * __bfq_entity_update_weight_prio. ++ */ ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ bfqq->last_wr_start_finish, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d", ++ bfqq->bfqd->wr_busy_queues); ++} ++ ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ if (bfqg->async_bfqq[i][j]) ++ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]); ++ if (bfqg->async_idle_bfqq) ++ bfq_bfqq_end_wr(bfqg->async_idle_bfqq); ++} ++ ++static void bfq_end_wr(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ spin_lock_irq(&bfqd->lock); ++ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ bfq_end_wr_async(bfqd); ++ ++ spin_unlock_irq(&bfqd->lock); ++} ++ ++static sector_t bfq_io_struct_pos(void *io_struct, bool request) ++{ ++ if (request) ++ return blk_rq_pos(io_struct); ++ else ++ return ((struct bio *)io_struct)->bi_iter.bi_sector; ++} ++ ++static int bfq_rq_close_to_sector(void *io_struct, bool request, ++ sector_t sector) ++{ ++ return abs(bfq_io_struct_pos(io_struct, request) - sector) <= ++ BFQQ_CLOSE_THR; ++} ++ ++static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ sector_t sector) ++{ ++ struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ struct rb_node *parent, *node; ++ struct bfq_queue *__bfqq; ++ ++ if (RB_EMPTY_ROOT(root)) ++ return NULL; ++ ++ /* ++ * First, if we find a request starting at the end of the last ++ * request, choose it. ++ */ ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL); ++ if (__bfqq) ++ return __bfqq; ++ ++ /* ++ * If the exact sector wasn't found, the parent of the NULL leaf ++ * will contain the closest sector (rq_pos_tree sorted by ++ * next_request position). ++ */ ++ __bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ if (blk_rq_pos(__bfqq->next_rq) < sector) ++ node = rb_next(&__bfqq->pos_node); ++ else ++ node = rb_prev(&__bfqq->pos_node); ++ if (!node) ++ return NULL; ++ ++ __bfqq = rb_entry(node, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ return NULL; ++} ++ ++static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd, ++ struct bfq_queue *cur_bfqq, ++ sector_t sector) ++{ ++ struct bfq_queue *bfqq; ++ ++ /* ++ * We shall notice if some of the queues are cooperating, ++ * e.g., working closely on the same area of the device. In ++ * that case, we can group them together and: 1) don't waste ++ * time idling, and 2) serve the union of their requests in ++ * the best possible order for throughput. ++ */ ++ bfqq = bfqq_find_close(bfqd, cur_bfqq, sector); ++ if (!bfqq || bfqq == cur_bfqq) ++ return NULL; ++ ++ return bfqq; ++} ++ ++static struct bfq_queue * ++bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ int process_refs, new_process_refs; ++ struct bfq_queue *__bfqq; ++ ++ /* ++ * If there are no process references on the new_bfqq, then it is ++ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain ++ * may have dropped their last reference (not just their last process ++ * reference). ++ */ ++ if (!bfqq_process_refs(new_bfqq)) ++ return NULL; ++ ++ /* Avoid a circular list and skip interim queue merges. */ ++ while ((__bfqq = new_bfqq->new_bfqq)) { ++ if (__bfqq == bfqq) ++ return NULL; ++ new_bfqq = __bfqq; ++ } ++ ++ process_refs = bfqq_process_refs(bfqq); ++ new_process_refs = bfqq_process_refs(new_bfqq); ++ /* ++ * If the process for the bfqq has gone away, there is no ++ * sense in merging the queues. ++ */ ++ if (process_refs == 0 || new_process_refs == 0) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", ++ new_bfqq->pid); ++ ++ /* ++ * Merging is just a redirection: the requests of the process ++ * owning one of the two queues are redirected to the other queue. ++ * The latter queue, in its turn, is set as shared if this is the ++ * first time that the requests of some process are redirected to ++ * it. ++ * ++ * We redirect bfqq to new_bfqq and not the opposite, because ++ * we are in the context of the process owning bfqq, thus we ++ * have the io_cq of this process. So we can immediately ++ * configure this io_cq to redirect the requests of the ++ * process to new_bfqq. In contrast, the io_cq of new_bfqq is ++ * not available any more (new_bfqq->bic == NULL). ++ * ++ * Anyway, even in case new_bfqq coincides with the in-service ++ * queue, redirecting requests the in-service queue is the ++ * best option, as we feed the in-service queue with new ++ * requests close to the last request served and, by doing so, ++ * are likely to increase the throughput. ++ */ ++ bfqq->new_bfqq = new_bfqq; ++ new_bfqq->ref += process_refs; ++ return new_bfqq; ++} ++ ++static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, ++ struct bfq_queue *new_bfqq) ++{ ++ if (bfq_too_late_for_merging(new_bfqq)) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "too late for bfq%d to be merged", ++ new_bfqq->pid); ++ return false; ++ } ++ ++ if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) || ++ (bfqq->ioprio_class != new_bfqq->ioprio_class)) ++ return false; ++ ++ /* ++ * If either of the queues has already been detected as seeky, ++ * then merging it with the other queue is unlikely to lead to ++ * sequential I/O. ++ */ ++ if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq)) ++ return false; ++ ++ /* ++ * Interleaved I/O is known to be done by (some) applications ++ * only for reads, so it does not make sense to merge async ++ * queues. ++ */ ++ if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq)) ++ return false; ++ ++ return true; ++} ++ ++/* ++ * Attempt to schedule a merge of bfqq with the currently in-service ++ * queue or with a close queue among the scheduled queues. Return ++ * NULL if no merge was scheduled, a pointer to the shared bfq_queue ++ * structure otherwise. ++ * ++ * The OOM queue is not allowed to participate to cooperation: in fact, since ++ * the requests temporarily redirected to the OOM queue could be redirected ++ * again to dedicated queues at any time, the state needed to correctly ++ * handle merging with the OOM queue would be quite complex and expensive ++ * to maintain. Besides, in such a critical condition as an out of memory, ++ * the benefits of queue merging may be little relevant, or even negligible. ++ * ++ * WARNING: queue merging may impair fairness among non-weight raised ++ * queues, for at least two reasons: 1) the original weight of a ++ * merged queue may change during the merged state, 2) even being the ++ * weight the same, a merged queue may be bloated with many more ++ * requests than the ones produced by its originally-associated ++ * process. ++ */ ++static struct bfq_queue * ++bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ void *io_struct, bool request) ++{ ++ struct bfq_queue *in_service_bfqq, *new_bfqq; ++ ++ /* ++ * Prevent bfqq from being merged if it has been created too ++ * long ago. The idea is that true cooperating processes, and ++ * thus their associated bfq_queues, are supposed to be ++ * created shortly after each other. This is the case, e.g., ++ * for KVM/QEMU and dump I/O threads. Basing on this ++ * assumption, the following filtering greatly reduces the ++ * probability that two non-cooperating processes, which just ++ * happen to do close I/O for some short time interval, have ++ * their queues merged by mistake. ++ */ ++ if (bfq_too_late_for_merging(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "would have looked for coop, but too late"); ++ return NULL; ++ } ++ ++ if (bfqq->new_bfqq) ++ return bfqq->new_bfqq; ++ ++ if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) ++ return NULL; ++ ++ /* If there is only one backlogged queue, don't search. */ ++ if (bfq_tot_busy_queues(bfqd) == 1) ++ return NULL; ++ ++ in_service_bfqq = bfqd->in_service_queue; ++ ++ if (in_service_bfqq && in_service_bfqq != bfqq && ++ likely(in_service_bfqq != &bfqd->oom_bfqq) && ++ bfq_rq_close_to_sector(io_struct, request, bfqd->in_serv_last_pos) && ++ bfqq->entity.parent == in_service_bfqq->entity.parent && ++ bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) { ++ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq); ++ if (new_bfqq) ++ return new_bfqq; ++ } ++ /* ++ * Check whether there is a cooperator among currently scheduled ++ * queues. The only thing we need is that the bio/request is not ++ * NULL, as we need it to establish whether a cooperator exists. ++ */ ++ new_bfqq = bfq_find_close_cooperator(bfqd, bfqq, ++ bfq_io_struct_pos(io_struct, request)); ++ ++ BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent); ++ ++ if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) && ++ bfq_may_be_close_cooperator(bfqq, new_bfqq)) ++ return bfq_setup_merge(bfqq, new_bfqq); ++ ++ return NULL; ++} ++ ++static void bfq_bfqq_save_state(struct bfq_queue *bfqq) ++{ ++ struct bfq_io_cq *bic = bfqq->bic; ++ ++ /* ++ * If !bfqq->bic, the queue is already shared or its requests ++ * have already been redirected to a shared queue; both idle window ++ * and weight raising state have already been saved. Do nothing. ++ */ ++ if (!bic) ++ return; ++ ++ bic->saved_ttime = bfqq->ttime; ++ bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq); ++ bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq); ++ bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq); ++ bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node); ++ if (unlikely(bfq_bfqq_just_created(bfqq) && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ bfqq->bfqd->low_latency)) { ++ /* ++ * bfqq being merged ritgh after being created: bfqq ++ * would have deserved interactive weight raising, but ++ * did not make it to be set in a weight-raised state, ++ * because of this early merge. Store directly the ++ * weight-raising state that would have been assigned ++ * to bfqq, so that to avoid that bfqq unjustly fails ++ * to enjoy weight raising if split soon. ++ */ ++ bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff; ++ bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd); ++ bic->saved_last_wr_start_finish = jiffies; ++ } else { ++ bic->saved_wr_coeff = bfqq->wr_coeff; ++ bic->saved_wr_start_at_switch_to_srt = ++ bfqq->wr_start_at_switch_to_srt; ++ bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish; ++ bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time; ++ } ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "bic %p wr_coeff %d start_finish %lu max_time %lu", ++ bic, bfqq->wr_coeff, bfqq->last_wr_start_finish, ++ bfqq->wr_cur_max_time); ++} ++ ++static void ++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", ++ (unsigned long) new_bfqq->pid); ++ BUG_ON(bfqq->bic && bfqq->bic == new_bfqq->bic); ++ /* Save weight raising and idle window of the merged queues */ ++ bfq_bfqq_save_state(bfqq); ++ bfq_bfqq_save_state(new_bfqq); ++ ++ if (bfq_bfqq_IO_bound(bfqq)) ++ bfq_mark_bfqq_IO_bound(new_bfqq); ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ /* ++ * If bfqq is weight-raised, then let new_bfqq inherit ++ * weight-raising. To reduce false positives, neglect the case ++ * where bfqq has just been created, but has not yet made it ++ * to be weight-raised (which may happen because EQM may merge ++ * bfqq even before bfq_add_request is executed for the first ++ * time for bfqq). Handling this case would however be very ++ * easy, thanks to the flag just_created. ++ */ ++ if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) { ++ new_bfqq->wr_coeff = bfqq->wr_coeff; ++ new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time; ++ new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish; ++ new_bfqq->wr_start_at_switch_to_srt = ++ bfqq->wr_start_at_switch_to_srt; ++ if (bfq_bfqq_busy(new_bfqq)) { ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > ++ bfq_tot_busy_queues(bfqd)); ++ } ++ ++ new_bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, new_bfqq, ++ "wr start after merge with %d, rais_max_time %u", ++ bfqq->pid, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */ ++ bfqq->wr_coeff = 1; ++ bfqq->entity.prio_changed = 1; ++ if (bfq_bfqq_busy(bfqq)) { ++ bfqd->wr_busy_queues--; ++ BUG_ON(bfqd->wr_busy_queues < 0); ++ } ++ ++ } ++ ++ bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d", ++ bfqd->wr_busy_queues); ++ ++ /* ++ * Merge queues (that is, let bic redirect its requests to new_bfqq) ++ */ ++ bic_set_bfqq(bic, new_bfqq, 1); ++ bfq_mark_bfqq_coop(new_bfqq); ++ /* ++ * new_bfqq now belongs to at least two bics (it is a shared queue): ++ * set new_bfqq->bic to NULL. bfqq either: ++ * - does not belong to any bic any more, and hence bfqq->bic must ++ * be set to NULL, or ++ * - is a queue whose owning bics have already been redirected to a ++ * different queue, hence the queue is destined to not belong to ++ * any bic soon and bfqq->bic is already NULL (therefore the next ++ * assignment causes no harm). ++ */ ++ new_bfqq->bic = NULL; ++ bfqq->bic = NULL; ++ /* release process reference to bfqq */ ++ bfq_put_queue(bfqq); ++} ++ ++static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ bool is_sync = op_is_sync(bio->bi_opf); ++ struct bfq_queue *bfqq = bfqd->bio_bfqq, *new_bfqq; ++ ++ assert_spin_locked(&bfqd->lock); ++ /* ++ * Disallow merge of a sync bio into an async request. ++ */ ++ if (is_sync && !rq_is_sync(rq)) ++ return false; ++ ++ /* ++ * Lookup the bfqq that this bio will be queued with. Allow ++ * merge only if rq is queued there. ++ */ ++ BUG_ON(!bfqd->bio_bfqq_set); ++ if (!bfqq) ++ return false; ++ ++ /* ++ * We take advantage of this function to perform an early merge ++ * of the queues of possible cooperating processes. ++ */ ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false); ++ BUG_ON(new_bfqq == bfqq); ++ if (new_bfqq) { ++ /* ++ * bic still points to bfqq, then it has not yet been ++ * redirected to some other bfq_queue, and a queue ++ * merge beween bfqq and new_bfqq can be safely ++ * fulfillled, i.e., bic can be redirected to new_bfqq ++ * and bfqq can be put. ++ */ ++ bfq_merge_bfqqs(bfqd, bfqd->bio_bic, bfqq, ++ new_bfqq); ++ /* ++ * If we get here, bio will be queued into new_queue, ++ * so use new_bfqq to decide whether bio and rq can be ++ * merged. ++ */ ++ bfqq = new_bfqq; ++ ++ /* ++ * Change also bqfd->bio_bfqq, as ++ * bfqd->bio_bic now points to new_bfqq, and ++ * this function may be invoked again (and then may ++ * use again bqfd->bio_bfqq). ++ */ ++ bfqd->bio_bfqq = bfqq; ++ } ++ return bfqq == RQ_BFQQ(rq); ++} ++ ++/* ++ * Set the maximum time for the in-service queue to consume its ++ * budget. This prevents seeky processes from lowering the throughput. ++ * In practice, a time-slice service scheme is used with seeky ++ * processes. ++ */ ++static void bfq_set_budget_timeout(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ unsigned int timeout_coeff; ++ ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) ++ timeout_coeff = 1; ++ else ++ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; ++ ++ bfqd->last_budget_start = ktime_get(); ++ ++ bfqq->budget_timeout = jiffies + ++ bfqd->bfq_timeout * timeout_coeff; ++ ++ bfq_log_bfqq(bfqd, bfqq, "%u", ++ jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff)); ++} ++ ++static void __bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq) { ++ bfq_clear_bfqq_fifo_expire(bfqq); ++ ++ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ if (time_is_before_jiffies(bfqq->last_wr_start_finish) && ++ bfqq->wr_coeff > 1 && ++ bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ time_is_before_jiffies(bfqq->budget_timeout)) { ++ /* ++ * For soft real-time queues, move the start ++ * of the weight-raising period forward by the ++ * time the queue has not received any ++ * service. Otherwise, a relatively long ++ * service delay is likely to cause the ++ * weight-raising period of the queue to end, ++ * because of the short duration of the ++ * weight-raising period of a soft real-time ++ * queue. It is worth noting that this move ++ * is not so dangerous for the other queues, ++ * because soft real-time queues are not ++ * greedy. ++ * ++ * To not add a further variable, we use the ++ * overloaded field budget_timeout to ++ * determine for how long the queue has not ++ * received service, i.e., how much time has ++ * elapsed since the queue expired. However, ++ * this is a little imprecise, because ++ * budget_timeout is set to jiffies if bfqq ++ * not only expires, but also remains with no ++ * request. ++ */ ++ if (time_after(bfqq->budget_timeout, ++ bfqq->last_wr_start_finish)) ++ bfqq->last_wr_start_finish += ++ jiffies - bfqq->budget_timeout; ++ else ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (time_is_after_jiffies(bfqq->last_wr_start_finish)) { ++ pr_crit( ++ "BFQ WARNING:last %lu budget %lu jiffies %lu", ++ bfqq->last_wr_start_finish, ++ bfqq->budget_timeout, ++ jiffies); ++ pr_crit("diff %lu", jiffies - ++ max_t(unsigned long, ++ bfqq->last_wr_start_finish, ++ bfqq->budget_timeout)); ++ bfqq->last_wr_start_finish = jiffies; ++ } ++ } ++ ++ bfq_set_budget_timeout(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "cur-budget = %d prio_class %d", ++ bfqq->entity.budget, bfqq->ioprio_class); ++ } else ++ bfq_log(bfqd, "NULL"); ++ ++ bfqd->in_service_queue = bfqq; ++} ++ ++/* ++ * Get and set a new queue for service. ++ */ ++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd); ++ ++ __bfq_set_in_service_queue(bfqd, bfqq); ++ return bfqq; ++} ++ ++static void bfq_arm_slice_timer(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ u32 sl; ++ ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ bfq_mark_bfqq_wait_request(bfqq); ++ ++ /* ++ * We don't want to idle for seeks, but we do want to allow ++ * fair distribution of slice time for a process doing back-to-back ++ * seeks. So allow a little bit of time for him to submit a new rq. ++ * ++ * To prevent processes with (partly) seeky workloads from ++ * being too ill-treated, grant them a small fraction of the ++ * assigned budget before reducing the waiting time to ++ * BFQ_MIN_TT. This happened to help reduce latency. ++ */ ++ sl = bfqd->bfq_slice_idle; ++ /* ++ * Unless the queue is being weight-raised or the scenario is ++ * asymmetric, grant only minimum idle time if the queue ++ * is seeky. A long idling is preserved for a weight-raised ++ * queue, or, more in general, in an asymemtric scenario, ++ * because a long idling is needed for guaranteeing to a queue ++ * its reserved share of the throughput (in particular, it is ++ * needed if the queue has a higher weight than some other ++ * queue). ++ */ ++ if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 && ++ bfq_symmetric_scenario(bfqd)) ++ sl = min_t(u32, sl, BFQ_MIN_TT); ++ ++ bfqd->last_idling_start = ktime_get(); ++ hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl), ++ HRTIMER_MODE_REL); ++ bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); ++ bfq_log(bfqd, "arm idle: %ld/%ld ms", ++ sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC); ++} ++ ++/* ++ * In autotuning mode, max_budget is dynamically recomputed as the ++ * amount of sectors transferred in timeout at the estimated peak ++ * rate. This enables BFQ to utilize a full timeslice with a full ++ * budget, even if the in-service queue is served at peak rate. And ++ * this maximises throughput with sequential workloads. ++ */ ++static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd) ++{ ++ return (u64)bfqd->peak_rate * USEC_PER_MSEC * ++ jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT; ++} ++ ++/* ++ * Update parameters related to throughput and responsiveness, as a ++ * function of the estimated peak rate. See comments on ++ * bfq_calc_max_budget(), and on the ref_wr_duration array. ++ */ ++static void update_thr_responsiveness_params(struct bfq_data *bfqd) ++{ ++ if (bfqd->bfq_user_max_budget == 0) { ++ bfqd->bfq_max_budget = ++ bfq_calc_max_budget(bfqd); ++ BUG_ON(bfqd->bfq_max_budget < 0); ++ bfq_log(bfqd, "new max_budget = %d", ++ bfqd->bfq_max_budget); ++ } ++} ++ ++static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq) ++{ ++ if (rq != NULL) { /* new rq dispatch now, reset accordingly */ ++ bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ; ++ bfqd->peak_rate_samples = 1; ++ bfqd->sequential_samples = 0; ++ bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size = ++ blk_rq_sectors(rq); ++ } else /* no new rq dispatched, just reset the number of samples */ ++ bfqd->peak_rate_samples = 0; /* full re-init on next disp. */ ++ ++ bfq_log(bfqd, ++ "at end, sample %u/%u tot_sects %llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ bfqd->tot_sectors_dispatched); ++} ++ ++static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq) ++{ ++ u32 rate, weight, divisor; ++ ++ /* ++ * For the convergence property to hold (see comments on ++ * bfq_update_peak_rate()) and for the assessment to be ++ * reliable, a minimum number of samples must be present, and ++ * a minimum amount of time must have elapsed. If not so, do ++ * not compute new rate. Just reset parameters, to get ready ++ * for a new evaluation attempt. ++ */ ++ if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES || ++ bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) { ++ bfq_log(bfqd, ++ "only resetting, delta_first %lluus samples %d", ++ bfqd->delta_from_first>>10, bfqd->peak_rate_samples); ++ goto reset_computation; ++ } ++ ++ /* ++ * If a new request completion has occurred after last ++ * dispatch, then, to approximate the rate at which requests ++ * have been served by the device, it is more precise to ++ * extend the observation interval to the last completion. ++ */ ++ bfqd->delta_from_first = ++ max_t(u64, bfqd->delta_from_first, ++ bfqd->last_completion - bfqd->first_dispatch); ++ ++ BUG_ON(bfqd->delta_from_first == 0); ++ /* ++ * Rate computed in sects/usec, and not sects/nsec, for ++ * precision issues. ++ */ ++ rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT, ++ div_u64(bfqd->delta_from_first, NSEC_PER_USEC)); ++ ++ bfq_log(bfqd, ++"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)", ++ bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ rate > 20<<BFQ_RATE_SHIFT); ++ ++ /* ++ * Peak rate not updated if: ++ * - the percentage of sequential dispatches is below 3/4 of the ++ * total, and rate is below the current estimated peak rate ++ * - rate is unreasonably high (> 20M sectors/sec) ++ */ ++ if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 && ++ rate <= bfqd->peak_rate) || ++ rate > 20<<BFQ_RATE_SHIFT) { ++ bfq_log(bfqd, ++ "goto reset, samples %u/%u rate/peak %llu/%llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ goto reset_computation; ++ } else { ++ bfq_log(bfqd, ++ "do update, samples %u/%u rate/peak %llu/%llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ } ++ ++ /* ++ * We have to update the peak rate, at last! To this purpose, ++ * we use a low-pass filter. We compute the smoothing constant ++ * of the filter as a function of the 'weight' of the new ++ * measured rate. ++ * ++ * As can be seen in next formulas, we define this weight as a ++ * quantity proportional to how sequential the workload is, ++ * and to how long the observation time interval is. ++ * ++ * The weight runs from 0 to 8. The maximum value of the ++ * weight, 8, yields the minimum value for the smoothing ++ * constant. At this minimum value for the smoothing constant, ++ * the measured rate contributes for half of the next value of ++ * the estimated peak rate. ++ * ++ * So, the first step is to compute the weight as a function ++ * of how sequential the workload is. Note that the weight ++ * cannot reach 9, because bfqd->sequential_samples cannot ++ * become equal to bfqd->peak_rate_samples, which, in its ++ * turn, holds true because bfqd->sequential_samples is not ++ * incremented for the first sample. ++ */ ++ weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples; ++ ++ /* ++ * Second step: further refine the weight as a function of the ++ * duration of the observation interval. ++ */ ++ weight = min_t(u32, 8, ++ div_u64(weight * bfqd->delta_from_first, ++ BFQ_RATE_REF_INTERVAL)); ++ ++ /* ++ * Divisor ranging from 10, for minimum weight, to 2, for ++ * maximum weight. ++ */ ++ divisor = 10 - weight; ++ BUG_ON(divisor == 0); ++ ++ /* ++ * Finally, update peak rate: ++ * ++ * peak_rate = peak_rate * (divisor-1) / divisor + rate / divisor ++ */ ++ bfqd->peak_rate *= divisor-1; ++ bfqd->peak_rate /= divisor; ++ rate /= divisor; /* smoothing constant alpha = 1/divisor */ ++ ++ bfq_log(bfqd, ++ "divisor %d tmp_peak_rate %llu tmp_rate %u", ++ divisor, ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT), ++ (u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT)); ++ ++ BUG_ON(bfqd->peak_rate == 0); ++ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT); ++ ++ bfqd->peak_rate += rate; ++ ++ /* ++ * For a very slow device, bfqd->peak_rate can reach 0 (see ++ * the minimum representable values reported in the comments ++ * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid ++ * divisions by zero where bfqd->peak_rate is used as a ++ * divisor. ++ */ ++ bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate); ++ ++ update_thr_responsiveness_params(bfqd); ++ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT); ++ ++reset_computation: ++ bfq_reset_rate_computation(bfqd, rq); ++} ++ ++/* ++ * Update the read/write peak rate (the main quantity used for ++ * auto-tuning, see update_thr_responsiveness_params()). ++ * ++ * It is not trivial to estimate the peak rate (correctly): because of ++ * the presence of sw and hw queues between the scheduler and the ++ * device components that finally serve I/O requests, it is hard to ++ * say exactly when a given dispatched request is served inside the ++ * device, and for how long. As a consequence, it is hard to know ++ * precisely at what rate a given set of requests is actually served ++ * by the device. ++ * ++ * On the opposite end, the dispatch time of any request is trivially ++ * available, and, from this piece of information, the "dispatch rate" ++ * of requests can be immediately computed. So, the idea in the next ++ * function is to use what is known, namely request dispatch times ++ * (plus, when useful, request completion times), to estimate what is ++ * unknown, namely in-device request service rate. ++ * ++ * The main issue is that, because of the above facts, the rate at ++ * which a certain set of requests is dispatched over a certain time ++ * interval can vary greatly with respect to the rate at which the ++ * same requests are then served. But, since the size of any ++ * intermediate queue is limited, and the service scheme is lossless ++ * (no request is silently dropped), the following obvious convergence ++ * property holds: the number of requests dispatched MUST become ++ * closer and closer to the number of requests completed as the ++ * observation interval grows. This is the key property used in ++ * the next function to estimate the peak service rate as a function ++ * of the observed dispatch rate. The function assumes to be invoked ++ * on every request dispatch. ++ */ ++static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq) ++{ ++ u64 now_ns = ktime_get_ns(); ++ ++ if (bfqd->peak_rate_samples == 0) { /* first dispatch */ ++ bfq_log(bfqd, ++ "goto reset, samples %d", ++ bfqd->peak_rate_samples) ; ++ bfq_reset_rate_computation(bfqd, rq); ++ goto update_last_values; /* will add one sample */ ++ } ++ ++ /* ++ * Device idle for very long: the observation interval lasting ++ * up to this dispatch cannot be a valid observation interval ++ * for computing a new peak rate (similarly to the late- ++ * completion event in bfq_completed_request()). Go to ++ * update_rate_and_reset to have the following three steps ++ * taken: ++ * - close the observation interval at the last (previous) ++ * request dispatch or completion ++ * - compute rate, if possible, for that observation interval ++ * - start a new observation interval with this dispatch ++ */ ++ if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC && ++ bfqd->rq_in_driver == 0) { ++ bfq_log(bfqd, ++"jumping to updating&resetting delta_last %lluus samples %d", ++ (now_ns - bfqd->last_dispatch)>>10, ++ bfqd->peak_rate_samples) ; ++ goto update_rate_and_reset; ++ } ++ ++ /* Update sampling information */ ++ bfqd->peak_rate_samples++; ++ ++ if ((bfqd->rq_in_driver > 0 || ++ now_ns - bfqd->last_completion < BFQ_MIN_TT) ++ && !BFQ_RQ_SEEKY(bfqd, bfqd->last_position, rq)) ++ bfqd->sequential_samples++; ++ ++ bfqd->tot_sectors_dispatched += blk_rq_sectors(rq); ++ ++ /* Reset max observed rq size every 32 dispatches */ ++ if (likely(bfqd->peak_rate_samples % 32)) ++ bfqd->last_rq_max_size = ++ max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size); ++ else ++ bfqd->last_rq_max_size = blk_rq_sectors(rq); ++ ++ bfqd->delta_from_first = now_ns - bfqd->first_dispatch; ++ ++ bfq_log(bfqd, ++ "added samples %u/%u tot_sects %llu delta_first %lluus", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ bfqd->tot_sectors_dispatched, ++ bfqd->delta_from_first>>10); ++ ++ /* Target observation interval not yet reached, go on sampling */ ++ if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL) ++ goto update_last_values; ++ ++update_rate_and_reset: ++ bfq_update_rate_reset(bfqd, rq); ++update_last_values: ++ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ if (RQ_BFQQ(rq) == bfqd->in_service_queue) ++ bfqd->in_serv_last_pos = bfqd->last_position; ++ bfqd->last_dispatch = now_ns; ++ ++ bfq_log(bfqd, ++ "delta_first %lluus last_pos %llu peak_rate %llu", ++ (now_ns - bfqd->first_dispatch)>>10, ++ (unsigned long long) bfqd->last_position, ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ bfq_log(bfqd, ++ "samples at end %d", bfqd->peak_rate_samples); ++} ++ ++/* ++ * Remove request from internal lists. ++ */ ++static void bfq_dispatch_remove(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * For consistency, the next instruction should have been ++ * executed after removing the request from the queue and ++ * dispatching it. We execute instead this instruction before ++ * bfq_remove_request() (and hence introduce a temporary ++ * inconsistency), for efficiency. In fact, should this ++ * dispatch occur for a non in-service bfqq, this anticipated ++ * increment prevents two counters related to bfqq->dispatched ++ * from risking to be, first, uselessly decremented, and then ++ * incremented again when the (new) value of bfqq->dispatched ++ * happens to be taken into account. ++ */ ++ bfqq->dispatched++; ++ bfq_update_peak_rate(q->elevator->elevator_data, rq); ++ ++ bfq_remove_request(q, rq); ++} ++ ++static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* ++ * If this bfqq is shared between multiple processes, check ++ * to make sure that those processes are still issuing I/Os ++ * within the mean seek distance. If not, it may be time to ++ * break the queues apart again. ++ */ ++ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq)) ++ bfq_mark_bfqq_split_coop(bfqq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ if (bfqq->dispatched == 0) ++ /* ++ * Overloading budget_timeout field to store ++ * the time at which the queue remains with no ++ * backlog and no outstanding request; used by ++ * the weight-raising mechanism. ++ */ ++ bfqq->budget_timeout = jiffies; ++ ++ bfq_del_bfqq_busy(bfqd, bfqq, true); ++ } else { ++ bfq_requeue_bfqq(bfqd, bfqq, true); ++ /* ++ * Resort priority tree of potential close cooperators. ++ */ ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ ++ /* ++ * All in-service entities must have been properly deactivated ++ * or requeued before executing the next function, which ++ * resets all in-service entites as no more in service. ++ */ ++ __bfq_bfqd_reset_in_service(bfqd); ++} ++ ++/** ++ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior. ++ * @bfqd: device data. ++ * @bfqq: queue to update. ++ * @reason: reason for expiration. ++ * ++ * Handle the feedback on @bfqq budget at queue expiration. ++ * See the body for detailed comments. ++ */ ++static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ enum bfqq_expiration reason) ++{ ++ struct request *next_rq; ++ int budget, min_budget; ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ min_budget = bfq_min_budget(bfqd); ++ ++ if (bfqq->wr_coeff == 1) ++ budget = bfqq->max_budget; ++ else /* ++ * Use a constant, low budget for weight-raised queues, ++ * to help achieve a low latency. Keep it slightly higher ++ * than the minimum possible budget, to cause a little ++ * bit fewer expirations. ++ */ ++ budget = 2 * min_budget; ++ ++ bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d", ++ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); ++ bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d", ++ budget, bfq_min_budget(bfqd)); ++ bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d", ++ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); ++ ++ if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) { ++ switch (reason) { ++ /* ++ * Caveat: in all the following cases we trade latency ++ * for throughput. ++ */ ++ case BFQ_BFQQ_TOO_IDLE: ++ /* ++ * This is the only case where we may reduce ++ * the budget: if there is no request of the ++ * process still waiting for completion, then ++ * we assume (tentatively) that the timer has ++ * expired because the batch of requests of ++ * the process could have been served with a ++ * smaller budget. Hence, betting that ++ * process will behave in the same way when it ++ * becomes backlogged again, we reduce its ++ * next budget. As long as we guess right, ++ * this budget cut reduces the latency ++ * experienced by the process. ++ * ++ * However, if there are still outstanding ++ * requests, then the process may have not yet ++ * issued its next request just because it is ++ * still waiting for the completion of some of ++ * the still outstanding ones. So in this ++ * subcase we do not reduce its budget, on the ++ * contrary we increase it to possibly boost ++ * the throughput, as discussed in the ++ * comments to the BUDGET_TIMEOUT case. ++ */ ++ if (bfqq->dispatched > 0) /* still outstanding reqs */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ else { ++ if (budget > 5 * min_budget) ++ budget -= 4 * min_budget; ++ else ++ budget = min_budget; ++ } ++ break; ++ case BFQ_BFQQ_BUDGET_TIMEOUT: ++ /* ++ * We double the budget here because it gives ++ * the chance to boost the throughput if this ++ * is not a seeky process (and has bumped into ++ * this timeout because of, e.g., ZBR). ++ */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_BUDGET_EXHAUSTED: ++ /* ++ * The process still has backlog, and did not ++ * let either the budget timeout or the disk ++ * idling timeout expire. Hence it is not ++ * seeky, has a short thinktime and may be ++ * happy with a higher budget too. So ++ * definitely increase the budget of this good ++ * candidate to boost the disk throughput. ++ */ ++ budget = min(budget * 4, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_NO_MORE_REQUESTS: ++ /* ++ * For queues that expire for this reason, it ++ * is particularly important to keep the ++ * budget close to the actual service they ++ * need. Doing so reduces the timestamp ++ * misalignment problem described in the ++ * comments in the body of ++ * __bfq_activate_entity. In fact, suppose ++ * that a queue systematically expires for ++ * BFQ_BFQQ_NO_MORE_REQUESTS and presents a ++ * new request in time to enjoy timestamp ++ * back-shifting. The larger the budget of the ++ * queue is with respect to the service the ++ * queue actually requests in each service ++ * slot, the more times the queue can be ++ * reactivated with the same virtual finish ++ * time. It follows that, even if this finish ++ * time is pushed to the system virtual time ++ * to reduce the consequent timestamp ++ * misalignment, the queue unjustly enjoys for ++ * many re-activations a lower finish time ++ * than all newly activated queues. ++ * ++ * The service needed by bfqq is measured ++ * quite precisely by bfqq->entity.service. ++ * Since bfqq does not enjoy device idling, ++ * bfqq->entity.service is equal to the number ++ * of sectors that the process associated with ++ * bfqq requested to read/write before waiting ++ * for request completions, or blocking for ++ * other reasons. ++ */ ++ budget = max_t(int, bfqq->entity.service, min_budget); ++ break; ++ default: ++ return; ++ } ++ } else if (!bfq_bfqq_sync(bfqq)) ++ /* ++ * Async queues get always the maximum possible ++ * budget, as for them we do not care about latency ++ * (in addition, their ability to dispatch is limited ++ * by the charging factor). ++ */ ++ budget = bfqd->bfq_max_budget; ++ ++ bfqq->max_budget = budget; ++ ++ if (bfqd->budgets_assigned >= bfq_stats_min_budgets && ++ !bfqd->bfq_user_max_budget) ++ bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); ++ ++ /* ++ * If there is still backlog, then assign a new budget, making ++ * sure that it is large enough for the next request. Since ++ * the finish time of bfqq must be kept in sync with the ++ * budget, be sure to call __bfq_bfqq_expire() *after* this ++ * update. ++ * ++ * If there is no backlog, then no need to update the budget; ++ * it will be updated on the arrival of a new request. ++ */ ++ next_rq = bfqq->next_rq; ++ if (next_rq) { ++ BUG_ON(reason == BFQ_BFQQ_TOO_IDLE || ++ reason == BFQ_BFQQ_NO_MORE_REQUESTS); ++ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", ++ next_rq ? blk_rq_sectors(next_rq) : 0, ++ bfqq->entity.budget); ++} ++ ++/* ++ * Return true if the process associated with bfqq is "slow". The slow ++ * flag is used, in addition to the budget timeout, to reduce the ++ * amount of service provided to seeky processes, and thus reduce ++ * their chances to lower the throughput. More details in the comments ++ * on the function bfq_bfqq_expire(). ++ * ++ * An important observation is in order: as discussed in the comments ++ * on the function bfq_update_peak_rate(), with devices with internal ++ * queues, it is hard if ever possible to know when and for how long ++ * an I/O request is processed by the device (apart from the trivial ++ * I/O pattern where a new request is dispatched only after the ++ * previous one has been completed). This makes it hard to evaluate ++ * the real rate at which the I/O requests of each bfq_queue are ++ * served. In fact, for an I/O scheduler like BFQ, serving a ++ * bfq_queue means just dispatching its requests during its service ++ * slot (i.e., until the budget of the queue is exhausted, or the ++ * queue remains idle, or, finally, a timeout fires). But, during the ++ * service slot of a bfq_queue, around 100 ms at most, the device may ++ * be even still processing requests of bfq_queues served in previous ++ * service slots. On the opposite end, the requests of the in-service ++ * bfq_queue may be completed after the service slot of the queue ++ * finishes. ++ * ++ * Anyway, unless more sophisticated solutions are used ++ * (where possible), the sum of the sizes of the requests dispatched ++ * during the service slot of a bfq_queue is probably the only ++ * approximation available for the service received by the bfq_queue ++ * during its service slot. And this sum is the quantity used in this ++ * function to evaluate the I/O speed of a process. ++ */ ++static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool compensate, enum bfqq_expiration reason, ++ unsigned long *delta_ms) ++{ ++ ktime_t delta_ktime; ++ u32 delta_usecs; ++ bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */ ++ ++ if (!bfq_bfqq_sync(bfqq)) ++ return false; ++ ++ if (compensate) ++ delta_ktime = bfqd->last_idling_start; ++ else ++ delta_ktime = ktime_get(); ++ delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start); ++ delta_usecs = ktime_to_us(delta_ktime); ++ ++ /* don't use too short time intervals */ ++ if (delta_usecs < 1000) { ++ if (blk_queue_nonrot(bfqd->queue)) ++ /* ++ * give same worst-case guarantees as idling ++ * for seeky ++ */ ++ *delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC; ++ else /* charge at least one seek */ ++ *delta_ms = bfq_slice_idle / NSEC_PER_MSEC; ++ ++ bfq_log(bfqd, "too short %u", delta_usecs); ++ ++ return slow; ++ } ++ ++ *delta_ms = delta_usecs / USEC_PER_MSEC; ++ ++ /* ++ * Use only long (> 20ms) intervals to filter out excessive ++ * spikes in service rate estimation. ++ */ ++ if (delta_usecs > 20000) { ++ /* ++ * Caveat for rotational devices: processes doing I/O ++ * in the slower disk zones tend to be slow(er) even ++ * if not seeky. In this respect, the estimated peak ++ * rate is likely to be an average over the disk ++ * surface. Accordingly, to not be too harsh with ++ * unlucky processes, a process is deemed slow only if ++ * its rate has been lower than half of the estimated ++ * peak rate. ++ */ ++ slow = bfqq->entity.service < bfqd->bfq_max_budget / 2; ++ bfq_log(bfqd, "relative rate %d/%d", ++ bfqq->entity.service, bfqd->bfq_max_budget); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "slow %d", slow); ++ ++ return slow; ++} ++ ++/* ++ * To be deemed as soft real-time, an application must meet two ++ * requirements. First, the application must not require an average ++ * bandwidth higher than the approximate bandwidth required to playback or ++ * record a compressed high-definition video. ++ * The next function is invoked on the completion of the last request of a ++ * batch, to compute the next-start time instant, soft_rt_next_start, such ++ * that, if the next request of the application does not arrive before ++ * soft_rt_next_start, then the above requirement on the bandwidth is met. ++ * ++ * The second requirement is that the request pattern of the application is ++ * isochronous, i.e., that, after issuing a request or a batch of requests, ++ * the application stops issuing new requests until all its pending requests ++ * have been completed. After that, the application may issue a new batch, ++ * and so on. ++ * For this reason the next function is invoked to compute ++ * soft_rt_next_start only for applications that meet this requirement, ++ * whereas soft_rt_next_start is set to infinity for applications that do ++ * not. ++ * ++ * Unfortunately, even a greedy (i.e., I/O-bound) application may ++ * happen to meet, occasionally or systematically, both the above ++ * bandwidth and isochrony requirements. This may happen at least in ++ * the following circumstances. First, if the CPU load is high. The ++ * application may stop issuing requests while the CPUs are busy ++ * serving other processes, then restart, then stop again for a while, ++ * and so on. The other circumstances are related to the storage ++ * device: the storage device is highly loaded or reaches a low-enough ++ * throughput with the I/O of the application (e.g., because the I/O ++ * is random and/or the device is slow). In all these cases, the ++ * I/O of the application may be simply slowed down enough to meet ++ * the bandwidth and isochrony requirements. To reduce the probability ++ * that greedy applications are deemed as soft real-time in these ++ * corner cases, a further rule is used in the computation of ++ * soft_rt_next_start: the return value of this function is forced to ++ * be higher than the maximum between the following two quantities. ++ * ++ * (a) Current time plus: (1) the maximum time for which the arrival ++ * of a request is waited for when a sync queue becomes idle, ++ * namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We ++ * postpone for a moment the reason for adding a few extra ++ * jiffies; we get back to it after next item (b). Lower-bounding ++ * the return value of this function with the current time plus ++ * bfqd->bfq_slice_idle tends to filter out greedy applications, ++ * because the latter issue their next request as soon as possible ++ * after the last one has been completed. In contrast, a soft ++ * real-time application spends some time processing data, after a ++ * batch of its requests has been completed. ++ * ++ * (b) Current value of bfqq->soft_rt_next_start. As pointed out ++ * above, greedy applications may happen to meet both the ++ * bandwidth and isochrony requirements under heavy CPU or ++ * storage-device load. In more detail, in these scenarios, these ++ * applications happen, only for limited time periods, to do I/O ++ * slowly enough to meet all the requirements described so far, ++ * including the filtering in above item (a). These slow-speed ++ * time intervals are usually interspersed between other time ++ * intervals during which these applications do I/O at a very high ++ * speed. Fortunately, exactly because of the high speed of the ++ * I/O in the high-speed intervals, the values returned by this ++ * function happen to be so high, near the end of any such ++ * high-speed interval, to be likely to fall *after* the end of ++ * the low-speed time interval that follows. These high values are ++ * stored in bfqq->soft_rt_next_start after each invocation of ++ * this function. As a consequence, if the last value of ++ * bfqq->soft_rt_next_start is constantly used to lower-bound the ++ * next value that this function may return, then, from the very ++ * beginning of a low-speed interval, bfqq->soft_rt_next_start is ++ * likely to be constantly kept so high that any I/O request ++ * issued during the low-speed interval is considered as arriving ++ * to soon for the application to be deemed as soft ++ * real-time. Then, in the high-speed interval that follows, the ++ * application will not be deemed as soft real-time, just because ++ * it will do I/O at a high speed. And so on. ++ * ++ * Getting back to the filtering in item (a), in the following two ++ * cases this filtering might be easily passed by a greedy ++ * application, if the reference quantity was just ++ * bfqd->bfq_slice_idle: ++ * 1) HZ is so low that the duration of a jiffy is comparable to or ++ * higher than bfqd->bfq_slice_idle. This happens, e.g., on slow ++ * devices with HZ=100. The time granularity may be so coarse ++ * that the approximation, in jiffies, of bfqd->bfq_slice_idle ++ * is rather lower than the exact value. ++ * 2) jiffies, instead of increasing at a constant rate, may stop increasing ++ * for a while, then suddenly 'jump' by several units to recover the lost ++ * increments. This seems to happen, e.g., inside virtual machines. ++ * To address this issue, in the filtering in (a) we do not use as a ++ * reference time interval just bfqd->bfq_slice_idle, but ++ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the ++ * minimum number of jiffies for which the filter seems to be quite ++ * precise also in embedded systems and KVM/QEMU virtual machines. ++ */ ++static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, ++"service_blkg %lu soft_rate %u sects/sec interval %u", ++ bfqq->service_from_backlogged, ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies_to_msecs(HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate)); ++ ++ return max3(bfqq->soft_rt_next_start, ++ bfqq->last_idle_bklogged + ++ HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4); ++} ++ ++static bool bfq_bfqq_injectable(struct bfq_queue *bfqq) ++{ ++ return BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 && ++ blk_queue_nonrot(bfqq->bfqd->queue) && ++ bfqq->bfqd->hw_tag; ++} ++ ++/** ++ * bfq_bfqq_expire - expire a queue. ++ * @bfqd: device owning the queue. ++ * @bfqq: the queue to expire. ++ * @compensate: if true, compensate for the time spent idling. ++ * @reason: the reason causing the expiration. ++ * ++ * If the process associated with bfqq does slow I/O (e.g., because it ++ * issues random requests), we charge bfqq with the time it has been ++ * in service instead of the service it has received (see ++ * bfq_bfqq_charge_time for details on how this goal is achieved). As ++ * a consequence, bfqq will typically get higher timestamps upon ++ * reactivation, and hence it will be rescheduled as if it had ++ * received more service than what it has actually received. In the ++ * end, bfqq receives less service in proportion to how slowly its ++ * associated process consumes its budgets (and hence how seriously it ++ * tends to lower the throughput). In addition, this time-charging ++ * strategy guarantees time fairness among slow processes. In ++ * contrast, if the process associated with bfqq is not slow, we ++ * charge bfqq exactly with the service it has received. ++ * ++ * Charging time to the first type of queues and the exact service to ++ * the other has the effect of using the WF2Q+ policy to schedule the ++ * former on a timeslice basis, without violating service domain ++ * guarantees among the latter. ++ */ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason) ++{ ++ bool slow; ++ unsigned long delta = 0; ++ struct bfq_entity *entity = &bfqq->entity; ++ int ref; ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* ++ * Check whether the process is slow (see bfq_bfqq_is_slow). ++ */ ++ slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta); ++ ++ /* ++ * As above explained, charge slow (typically seeky) and ++ * timed-out queues with the time and not the service ++ * received, to favor sequential workloads. ++ * ++ * Processes doing I/O in the slower disk zones will tend to ++ * be slow(er) even if not seeky. Therefore, since the ++ * estimated peak rate is actually an average over the disk ++ * surface, these processes may timeout just for bad luck. To ++ * avoid punishing them, do not charge time to processes that ++ * succeeded in consuming at least 2/3 of their budget. This ++ * allows BFQ to preserve enough elasticity to still perform ++ * bandwidth, and not time, distribution with little unlucky ++ * or quasi-sequential processes. ++ */ ++ if (bfqq->wr_coeff == 1 && ++ (slow || ++ (reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ bfq_bfqq_budget_left(bfqq) >= entity->budget / 3))) ++ bfq_bfqq_charge_time(bfqd, bfqq, delta); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ if (reason == BFQ_BFQQ_TOO_IDLE && ++ entity->service <= 2 * entity->budget / 10) ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (bfqd->low_latency && bfqq->wr_coeff == 1) ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * If we get here, and there are no outstanding ++ * requests, then the request pattern is isochronous ++ * (see the comments on the function ++ * bfq_bfqq_softrt_next_start()). Thus we can compute ++ * soft_rt_next_start. And we do it, unless bfqq is in ++ * interactive weight raising. We do not do it in the ++ * latter subcase, for the following reason. bfqq may ++ * be conveying the I/O needed to load a soft ++ * real-time application. Such an application will ++ * actually exhibit a soft real-time I/O pattern after ++ * it finally starts doing its job. But, if ++ * soft_rt_next_start is computed here for an ++ * interactive bfqq, and bfqq had received a lot of ++ * service before remaining with no outstanding ++ * request (likely to happen on a fast device), then ++ * soft_rt_next_start would be assigned such a high ++ * value that, for a very long time, bfqq would be ++ * prevented from being possibly considered as soft ++ * real time. ++ * ++ * If, instead, the queue still has outstanding ++ * requests, then we have to wait for the completion ++ * of all the outstanding requests to discover whether ++ * the request pattern is actually isochronous. ++ */ ++ BUG_ON(bfq_tot_busy_queues(bfqd) < 1); ++ if (bfqq->dispatched == 0 && ++ bfqq->wr_coeff != bfqd->bfq_wr_coeff) { ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu", ++ bfqq->soft_rt_next_start); ++ } else if (bfqq->dispatched > 0) { ++ /* ++ * Schedule an update of soft_rt_next_start to when ++ * the task may be discovered to be isochronous. ++ */ ++ bfq_mark_bfqq_softrt_update(bfqq); ++ } ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "expire (%s, slow %d, num_disp %d, short %d, weight %d, serv %d/%d)", ++ reason_name[reason], slow, bfqq->dispatched, ++ bfq_bfqq_has_short_ttime(bfqq), entity->weight, ++ entity->service, entity->budget); ++ ++ /* ++ * Increase, decrease or leave budget unchanged according to ++ * reason. ++ */ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); ++ BUG_ON(bfqq->next_rq == NULL && ++ bfqq->entity.budget < bfqq->entity.service); ++ ref = bfqq->ref; ++ __bfq_bfqq_expire(bfqd, bfqq); ++ ++ if (ref == 1) /* bfqq is gone, no more actions on it */ ++ return; ++ ++ BUG_ON(ref > 1 && ++ !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED && ++ !bfq_class_idle(bfqq)); ++ ++ bfqq->injected_service = 0; ++ ++ /* mark bfqq as waiting a request only if a bic still points to it */ ++ if (!bfq_bfqq_busy(bfqq) && ++ reason != BFQ_BFQQ_BUDGET_TIMEOUT && ++ reason != BFQ_BFQQ_BUDGET_EXHAUSTED) { ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(bfqq->next_rq); ++ bfq_mark_bfqq_non_blocking_wait_rq(bfqq); ++ /* ++ * Not setting service to 0, because, if the next rq ++ * arrives in time, the queue will go on receiving ++ * service with this same budget (as if it never expired) ++ */ ++ } else { ++ entity->service = 0; ++ bfq_log_bfqq(bfqd, bfqq, "resetting service"); ++ } ++ ++ /* ++ * Reset the received-service counter for every parent entity. ++ * Differently from what happens with bfqq->entity.service, ++ * the resetting of this counter never needs to be postponed ++ * for parent entities. In fact, in case bfqq may have a ++ * chance to go on being served using the last, partially ++ * consumed budget, bfqq->entity.service needs to be kept, ++ * because if bfqq then actually goes on being served using ++ * the same budget, the last value of bfqq->entity.service is ++ * needed to properly decrement bfqq->entity.budget by the ++ * portion already consumed. In contrast, it is not necessary ++ * to keep entity->service for parent entities too, because ++ * the bubble up of the new value of bfqq->entity.budget will ++ * make sure that the budgets of parent entities are correct, ++ * even in case bfqq and thus parent entities go on receiving ++ * service with the same budget. ++ */ ++ entity = entity->parent; ++ for_each_entity(entity) ++ entity->service = 0; ++} ++ ++/* ++ * Budget timeout is not implemented through a dedicated timer, but ++ * just checked on request arrivals and completions, as well as on ++ * idle timer expirations. ++ */ ++static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) ++{ ++ return time_is_before_eq_jiffies(bfqq->budget_timeout); ++} ++ ++/* ++ * If we expire a queue that is actively waiting (i.e., with the ++ * device idled) for the arrival of a new request, then we may incur ++ * the timestamp misalignment problem described in the body of the ++ * function __bfq_activate_entity. Hence we return true only if this ++ * condition does not hold, or if the queue is slow enough to deserve ++ * only to be kicked off for preserving a high throughput. ++ */ ++static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "wait_request %d left %d timeout %d", ++ bfq_bfqq_wait_request(bfqq), ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3, ++ bfq_bfqq_budget_timeout(bfqq)); ++ ++ return (!bfq_bfqq_wait_request(bfqq) || ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3) ++ && ++ bfq_bfqq_budget_timeout(bfqq); ++} ++ ++static bool idling_boosts_thr_without_issues(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bool rot_without_queueing = ++ !blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag, ++ bfqq_sequential_and_IO_bound, ++ idling_boosts_thr; ++ ++ bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) && ++ bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq); ++ /* ++ * The next variable takes into account the cases where idling ++ * boosts the throughput. ++ * ++ * The value of the variable is computed considering, first, that ++ * idling is virtually always beneficial for the throughput if: ++ * (a) the device is not NCQ-capable and rotational, or ++ * (b) regardless of the presence of NCQ, the device is rotational and ++ * the request pattern for bfqq is I/O-bound and sequential, or ++ * (c) regardless of whether it is rotational, the device is ++ * not NCQ-capable and the request pattern for bfqq is ++ * I/O-bound and sequential. ++ * ++ * Secondly, and in contrast to the above item (b), idling an ++ * NCQ-capable flash-based device would not boost the ++ * throughput even with sequential I/O; rather it would lower ++ * the throughput in proportion to how fast the device ++ * is. Accordingly, the next variable is true if any of the ++ * above conditions (a), (b) or (c) is true, and, in ++ * particular, happens to be false if bfqd is an NCQ-capable ++ * flash-based device. ++ */ ++ idling_boosts_thr = rot_without_queueing || ++ ((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) && ++ bfqq_sequential_and_IO_bound); ++ ++ bfq_log_bfqq(bfqd, bfqq, "idling_boosts_thr %d", idling_boosts_thr); ++ ++ /* ++ * The return value of this function is equal to that of ++ * idling_boosts_thr, unless a special case holds. In this ++ * special case, described below, idling may cause problems to ++ * weight-raised queues. ++ * ++ * When the request pool is saturated (e.g., in the presence ++ * of write hogs), if the processes associated with ++ * non-weight-raised queues ask for requests at a lower rate, ++ * then processes associated with weight-raised queues have a ++ * higher probability to get a request from the pool ++ * immediately (or at least soon) when they need one. Thus ++ * they have a higher probability to actually get a fraction ++ * of the device throughput proportional to their high ++ * weight. This is especially true with NCQ-capable drives, ++ * which enqueue several requests in advance, and further ++ * reorder internally-queued requests. ++ * ++ * For this reason, we force to false the return value if ++ * there are weight-raised busy queues. In this case, and if ++ * bfqq is not weight-raised, this guarantees that the device ++ * is not idled for bfqq (if, instead, bfqq is weight-raised, ++ * then idling will be guaranteed by another variable, see ++ * below). Combined with the timestamping rules of BFQ (see ++ * [1] for details), this behavior causes bfqq, and hence any ++ * sync non-weight-raised queue, to get a lower number of ++ * requests served, and thus to ask for a lower number of ++ * requests from the request pool, before the busy ++ * weight-raised queues get served again. This often mitigates ++ * starvation problems in the presence of heavy write ++ * workloads and NCQ, thereby guaranteeing a higher ++ * application and system responsiveness in these hostile ++ * scenarios. ++ */ ++ return idling_boosts_thr && ++ bfqd->wr_busy_queues == 0; ++} ++ ++/* ++ * There is a case where idling must be performed not for ++ * throughput concerns, but to preserve service guarantees. ++ * ++ * To introduce this case, we can note that allowing the drive ++ * to enqueue more than one request at a time, and hence ++ * delegating de facto final scheduling decisions to the ++ * drive's internal scheduler, entails loss of control on the ++ * actual request service order. In particular, the critical ++ * situation is when requests from different processes happen ++ * to be present, at the same time, in the internal queue(s) ++ * of the drive. In such a situation, the drive, by deciding ++ * the service order of the internally-queued requests, does ++ * determine also the actual throughput distribution among ++ * these processes. But the drive typically has no notion or ++ * concern about per-process throughput distribution, and ++ * makes its decisions only on a per-request basis. Therefore, ++ * the service distribution enforced by the drive's internal ++ * scheduler is likely to coincide with the desired ++ * device-throughput distribution only in a completely ++ * symmetric scenario where: ++ * (i) each of these processes must get the same throughput as ++ * the others; ++ * (ii) the I/O of each process has the same properties, in ++ * terms of locality (sequential or random), direction ++ * (reads or writes), request sizes, greediness ++ * (from I/O-bound to sporadic), and so on. ++ * In fact, in such a scenario, the drive tends to treat ++ * the requests of each of these processes in about the same ++ * way as the requests of the others, and thus to provide ++ * each of these processes with about the same throughput ++ * (which is exactly the desired throughput distribution). In ++ * contrast, in any asymmetric scenario, device idling is ++ * certainly needed to guarantee that bfqq receives its ++ * assigned fraction of the device throughput (see [1] for ++ * details). ++ * The problem is that idling may significantly reduce ++ * throughput with certain combinations of types of I/O and ++ * devices. An important example is sync random I/O, on flash ++ * storage with command queueing. So, unless bfqq falls in the ++ * above cases where idling also boosts throughput, it would ++ * be important to check conditions (i) and (ii) accurately, ++ * so as to avoid idling when not strictly needed for service ++ * guarantees. ++ * ++ * Unfortunately, it is extremely difficult to thoroughly ++ * check condition (ii). And, in case there are active groups, ++ * it becomes very difficult to check condition (i) too. In ++ * fact, if there are active groups, then, for condition (i) ++ * to become false, it is enough that an active group contains ++ * more active processes or sub-groups than some other active ++ * group. More precisely, for condition (i) to hold because of ++ * such a group, it is not even necessary that the group is ++ * (still) active: it is sufficient that, even if the group ++ * has become inactive, some of its descendant processes still ++ * have some request already dispatched but still waiting for ++ * completion. In fact, requests have still to be guaranteed ++ * their share of the throughput even after being ++ * dispatched. In this respect, it is easy to show that, if a ++ * group frequently becomes inactive while still having ++ * in-flight requests, and if, when this happens, the group is ++ * not considered in the calculation of whether the scenario ++ * is asymmetric, then the group may fail to be guaranteed its ++ * fair share of the throughput (basically because idling may ++ * not be performed for the descendant processes of the group, ++ * but it had to be). We address this issue with the ++ * following bi-modal behavior, implemented in the function ++ * bfq_symmetric_scenario(). ++ * ++ * If there are groups with requests waiting for completion ++ * (as commented above, some of these groups may even be ++ * already inactive), then the scenario is tagged as ++ * asymmetric, conservatively, without checking any of the ++ * conditions (i) and (ii). So the device is idled for bfqq. ++ * This behavior matches also the fact that groups are created ++ * exactly if controlling I/O is a primary concern (to ++ * preserve bandwidth and latency guarantees). ++ * ++ * On the opposite end, if there are no groups with requests ++ * waiting for completion, then only condition (i) is actually ++ * controlled, i.e., provided that condition (i) holds, idling ++ * is not performed, regardless of whether condition (ii) ++ * holds. In other words, only if condition (i) does not hold, ++ * then idling is allowed, and the device tends to be ++ * prevented from queueing many requests, possibly of several ++ * processes. Since there are no groups with requests waiting ++ * for completion, then, to control condition (i) it is enough ++ * to check just whether all the queues with requests waiting ++ * for completion also have the same weight. ++ * ++ * Not checking condition (ii) evidently exposes bfqq to the ++ * risk of getting less throughput than its fair share. ++ * However, for queues with the same weight, a further ++ * mechanism, preemption, mitigates or even eliminates this ++ * problem. And it does so without consequences on overall ++ * throughput. This mechanism and its benefits are explained ++ * in the next three paragraphs. ++ * ++ * Even if a queue, say Q, is expired when it remains idle, Q ++ * can still preempt the new in-service queue if the next ++ * request of Q arrives soon (see the comments on ++ * bfq_bfqq_update_budg_for_activation). If all queues and ++ * groups have the same weight, this form of preemption, ++ * combined with the hole-recovery heuristic described in the ++ * comments on function bfq_bfqq_update_budg_for_activation, ++ * are enough to preserve a correct bandwidth distribution in ++ * the mid term, even without idling. In fact, even if not ++ * idling allows the internal queues of the device to contain ++ * many requests, and thus to reorder requests, we can rather ++ * safely assume that the internal scheduler still preserves a ++ * minimum of mid-term fairness. ++ * ++ * More precisely, this preemption-based, idleless approach ++ * provides fairness in terms of IOPS, and not sectors per ++ * second. This can be seen with a simple example. Suppose ++ * that there are two queues with the same weight, but that ++ * the first queue receives requests of 8 sectors, while the ++ * second queue receives requests of 1024 sectors. In ++ * addition, suppose that each of the two queues contains at ++ * most one request at a time, which implies that each queue ++ * always remains idle after it is served. Finally, after ++ * remaining idle, each queue receives very quickly a new ++ * request. It follows that the two queues are served ++ * alternatively, preempting each other if needed. This ++ * implies that, although both queues have the same weight, ++ * the queue with large requests receives a service that is ++ * 1024/8 times as high as the service received by the other ++ * queue. ++ * ++ * The motivation for using preemption instead of idling (for ++ * queues with the same weight) is that, by not idling, ++ * service guarantees are preserved (completely or at least in ++ * part) without minimally sacrificing throughput. And, if ++ * there is no active group, then the primary expectation for ++ * this device is probably a high throughput. ++ * ++ * We are now left only with explaining the additional ++ * compound condition that is checked below for deciding ++ * whether the scenario is asymmetric. To explain this ++ * compound condition, we need to add that the function ++ * bfq_symmetric_scenario checks the weights of only ++ * non-weight-raised queues, for efficiency reasons (see ++ * comments on bfq_weights_tree_add()). Then the fact that ++ * bfqq is weight-raised is checked explicitly here. More ++ * precisely, the compound condition below takes into account ++ * also the fact that, even if bfqq is being weight-raised, ++ * the scenario is still symmetric if all queues with requests ++ * waiting for completion happen to be ++ * weight-raised. Actually, we should be even more precise ++ * here, and differentiate between interactive weight raising ++ * and soft real-time weight raising. ++ * ++ * As a side note, it is worth considering that the above ++ * device-idling countermeasures may however fail in the ++ * following unlucky scenario: if idling is (correctly) ++ * disabled in a time period during which all symmetry ++ * sub-conditions hold, and hence the device is allowed to ++ * enqueue many requests, but at some later point in time some ++ * sub-condition stops to hold, then it may become impossible ++ * to let requests be served in the desired order until all ++ * the requests already queued in the device have been served. ++ */ ++static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bool asymmetric_scenario = (bfqq->wr_coeff > 1 && ++ bfqd->wr_busy_queues < ++ bfq_tot_busy_queues(bfqd)) || ++ !bfq_symmetric_scenario(bfqd); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wr_coeff %d wr_busy %d busy %d asymmetric %d", ++ bfqq->wr_coeff, ++ bfqd->wr_busy_queues, ++ bfq_tot_busy_queues(bfqd), ++ asymmetric_scenario); ++ ++ return asymmetric_scenario; ++} ++ ++/* ++ * For a queue that becomes empty, device idling is allowed only if ++ * this function returns true for that queue. As a consequence, since ++ * device idling plays a critical role for both throughput boosting ++ * and service guarantees, the return value of this function plays a ++ * critical role as well. ++ * ++ * In a nutshell, this function returns true only if idling is ++ * beneficial for throughput or, even if detrimental for throughput, ++ * idling is however necessary to preserve service guarantees (low ++ * latency, desired throughput distribution, ...). In particular, on ++ * NCQ-capable devices, this function tries to return false, so as to ++ * help keep the drives' internal queues full, whenever this helps the ++ * device boost the throughput without causing any service-guarantee ++ * issue. ++ * ++ * Most of the issues taken into account to get the return value of ++ * this function are not trivial. We discuss these issues in the two ++ * functions providing the main pieces of information needed by this ++ * function. ++ */ ++static bool bfq_better_to_idle(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ bool idling_boosts_thr_with_no_issue, idling_needed_for_service_guar; ++ ++ if (unlikely(bfqd->strict_guarantees)) ++ return true; ++ ++ /* ++ * Idling is performed only if slice_idle > 0. In addition, we ++ * do not idle if ++ * (a) bfqq is async ++ * (b) bfqq is in the idle io prio class: in this case we do ++ * not idle because we want to minimize the bandwidth that ++ * queues in this class can steal to higher-priority queues ++ */ ++ if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) || ++ bfq_class_idle(bfqq)) ++ return false; ++ ++ idling_boosts_thr_with_no_issue = ++ idling_boosts_thr_without_issues(bfqd, bfqq); ++ ++ idling_needed_for_service_guar = ++ idling_needed_for_service_guarantees(bfqd, bfqq); ++ ++ /* ++ * We have now the two components we need to compute the ++ * return value of the function, which is true only if idling ++ * either boosts the throughput (without issues), or is ++ * necessary to preserve service guarantees. ++ */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wr_busy %d boosts %d IO-bound %d guar %d", ++ bfqd->wr_busy_queues, ++ idling_boosts_thr_with_no_issue, ++ bfq_bfqq_IO_bound(bfqq), ++ idling_needed_for_service_guar); ++ ++ return idling_boosts_thr_with_no_issue || ++ idling_needed_for_service_guar; ++} ++ ++/* ++ * If the in-service queue is empty but the function bfq_better_to_idle ++ * returns true, then: ++ * 1) the queue must remain in service and cannot be expired, and ++ * 2) the device must be idled to wait for the possible arrival of a new ++ * request for the queue. ++ * See the comments on the function bfq_better_to_idle for the reasons ++ * why performing device idling is the best choice to boost the throughput ++ * and preserve service guarantees when bfq_better_to_idle itself ++ * returns true. ++ */ ++static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) ++{ ++ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq); ++} ++ ++static struct bfq_queue *bfq_choose_bfqq_for_injection(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ /* ++ * A linear search; but, with a high probability, very few ++ * steps are needed to find a candidate queue, i.e., a queue ++ * with enough budget left for its next request. In fact: ++ * - BFQ dynamically updates the budget of every queue so as ++ * to accomodate the expected backlog of the queue; ++ * - if a queue gets all its requests dispatched as injected ++ * service, then the queue is removed from the active list ++ * (and re-added only if it gets new requests, but with ++ * enough budget for its new backlog). ++ */ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ if (!RB_EMPTY_ROOT(&bfqq->sort_list) && ++ bfq_serv_to_charge(bfqq->next_rq, bfqq) <= ++ bfq_bfqq_budget_left(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, "returned this queue"); ++ return bfqq; ++ } ++ ++ bfq_log(bfqd, "no queue found"); ++ return NULL; ++} ++ ++/* ++ * Select a queue for service. If we have a current queue in service, ++ * check whether to continue servicing it, or retrieve and set a new one. ++ */ ++static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ struct request *next_rq; ++ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ ++ bfqq = bfqd->in_service_queue; ++ if (!bfqq) ++ goto new_queue; ++ ++ bfq_log_bfqq(bfqd, bfqq, "already in-service queue"); ++ ++ /* ++ * Do not expire bfqq for budget timeout if bfqq may be about ++ * to enjoy device idling. The reason why, in this case, we ++ * prevent bfqq from expiring is the same as in the comments ++ * on the case where bfq_bfqq_must_idle() returns true, in ++ * bfq_completed_request(). ++ */ ++ if (bfq_may_expire_for_budg_timeout(bfqq) && ++ !bfq_bfqq_must_idle(bfqq)) ++ goto expire; ++ ++check_queue: ++ /* ++ * This loop is rarely executed more than once. Even when it ++ * happens, it is much more convenient to re-execute this loop ++ * than to return NULL and trigger a new dispatch to get a ++ * request served. ++ */ ++ next_rq = bfqq->next_rq; ++ /* ++ * If bfqq has requests queued and it has enough budget left to ++ * serve them, keep the queue, otherwise expire it. ++ */ ++ if (next_rq) { ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ if (bfq_serv_to_charge(next_rq, bfqq) > ++ bfq_bfqq_budget_left(bfqq)) { ++ /* ++ * Expire the queue for budget exhaustion, ++ * which makes sure that the next budget is ++ * enough to serve the next request, even if ++ * it comes from the fifo expired path. ++ */ ++ reason = BFQ_BFQQ_BUDGET_EXHAUSTED; ++ goto expire; ++ } else { ++ /* ++ * The idle timer may be pending because we may ++ * not disable disk idling even when a new request ++ * arrives. ++ */ ++ if (bfq_bfqq_wait_request(bfqq)) { ++ /* ++ * If we get here: 1) at least a new request ++ * has arrived but we have not disabled the ++ * timer because the request was too small, ++ * 2) then the block layer has unplugged ++ * the device, causing the dispatch to be ++ * invoked. ++ * ++ * Since the device is unplugged, now the ++ * requests are probably large enough to ++ * provide a reasonable throughput. ++ * So we disable idling. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ hrtimer_try_to_cancel(&bfqd->idle_slice_timer); ++ } ++ goto keep_queue; ++ } ++ } ++ ++ /* ++ * No requests pending. However, if the in-service queue is idling ++ * for a new request, or has requests waiting for a completion and ++ * may idle after their completion, then keep it anyway. ++ * ++ * Yet, to boost throughput, inject service from other queues if ++ * possible. ++ */ ++ if (bfq_bfqq_wait_request(bfqq) || ++ (bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) { ++ if (bfq_bfqq_injectable(bfqq) && ++ bfqq->injected_service * bfqq->inject_coeff < ++ bfqq->entity.service * 10) { ++ bfq_log_bfqq(bfqd, bfqq, "looking for queue for injection"); ++ bfqq = bfq_choose_bfqq_for_injection(bfqd); ++ } else { ++ if (BFQQ_SEEKY(bfqq)) ++ bfq_log_bfqq(bfqd, bfqq, ++ "injection saturated %d * %d >= %d * 10", ++ bfqq->injected_service, bfqq->inject_coeff, ++ bfqq->entity.service); ++ bfqq = NULL; ++ } ++ goto keep_queue; ++ } ++ ++ reason = BFQ_BFQQ_NO_MORE_REQUESTS; ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, false, reason); ++new_queue: ++ bfqq = bfq_set_in_service_queue(bfqd); ++ if (bfqq) { ++ bfq_log_bfqq(bfqd, bfqq, "checking new queue"); ++ goto check_queue; ++ } ++keep_queue: ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, "returned this queue"); ++ else ++ bfq_log(bfqd, "no queue returned"); ++ ++ return bfqq; ++} ++ ++static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */ ++ BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight != ++ entity->orig_weight * bfqq->wr_coeff); ++ if (entity->prio_changed) ++ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); ++ ++ /* ++ * If the queue was activated in a burst, or too much ++ * time has elapsed from the beginning of this ++ * weight-raising period, then end weight raising. ++ */ ++ if (bfq_bfqq_in_large_burst(bfqq)) ++ bfq_bfqq_end_wr(bfqq); ++ else if (time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time)) { ++ if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time || ++ time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt + ++ bfq_wr_duration(bfqd))) ++ bfq_bfqq_end_wr(bfqq); ++ else { ++ switch_back_to_interactive_wr(bfqq, bfqd); ++ BUG_ON(time_is_after_jiffies( ++ bfqq->last_wr_start_finish)); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "back to interactive wr"); ++ } ++ } ++ if (bfqq->wr_coeff > 1 && ++ bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time && ++ bfqq->service_from_wr > max_service_from_wr) { ++ /* see comments on max_service_from_wr */ ++ bfq_bfqq_end_wr(bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "too much service"); ++ } ++ } ++ /* ++ * To improve latency (for this or other queues), immediately ++ * update weight both if it must be raised and if it must be ++ * lowered. Since, entity may be on some active tree here, and ++ * might have a pending change of its ioprio class, invoke ++ * next function with the last parameter unset (see the ++ * comments on the function). ++ */ ++ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1)) ++ __bfq_entity_update_weight_prio(bfq_entity_service_tree(entity), ++ entity, false); ++} ++ ++/* ++ * Dispatch next request from bfqq. ++ */ ++static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct request *rq = bfqq->next_rq; ++ unsigned long service_to_charge; ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(!rq); ++ service_to_charge = bfq_serv_to_charge(rq, bfqq); ++ ++ BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq)); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ bfq_bfqq_served(bfqq, service_to_charge); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ bfq_dispatch_remove(bfqd->queue, rq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "dispatched %u sec req (%llu), budg left %d, new disp_nr %d", ++ blk_rq_sectors(rq), ++ (unsigned long long) blk_rq_pos(rq), ++ bfq_bfqq_budget_left(bfqq), ++ bfqq->dispatched); ++ ++ if (bfqq != bfqd->in_service_queue) { ++ if (likely(bfqd->in_service_queue)) { ++ bfqd->in_service_queue->injected_service += ++ bfq_serv_to_charge(rq, bfqq); ++ bfq_log_bfqq(bfqd, bfqd->in_service_queue, ++ "injected_service increased to %d", ++ bfqd->in_service_queue->injected_service); ++ } ++ goto return_rq; ++ } ++ ++ /* ++ * If weight raising has to terminate for bfqq, then next ++ * function causes an immediate update of bfqq's weight, ++ * without waiting for next activation. As a consequence, on ++ * expiration, bfqq will be timestamped as if has never been ++ * weight-raised during this service slot, even if it has ++ * received part or even most of the service as a ++ * weight-raised queue. This inflates bfqq's timestamps, which ++ * is beneficial, as bfqq is then more willing to leave the ++ * device immediately to possible other weight-raised queues. ++ */ ++ bfq_update_wr_data(bfqd, bfqq); ++ ++ /* ++ * Expire bfqq, pretending that its budget expired, if bfqq ++ * belongs to CLASS_IDLE and other queues are waiting for ++ * service. ++ */ ++ if (!(bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq))) ++ goto return_rq; ++ ++ bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED); ++ ++return_rq: ++ return rq; ++} ++ ++static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) ++{ ++ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; ++ ++ bfq_log(bfqd, "dispatch_non_empty %d busy_queues %d", ++ !list_empty_careful(&bfqd->dispatch), bfq_tot_busy_queues(bfqd) > 0); ++ ++ /* ++ * Avoiding lock: a race on bfqd->busy_queues should cause at ++ * most a call to dispatch for nothing ++ */ ++ return !list_empty_careful(&bfqd->dispatch) || ++ bfq_tot_busy_queues(bfqd) > 0; ++} ++ ++static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) ++{ ++ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; ++ struct request *rq = NULL; ++ struct bfq_queue *bfqq = NULL; ++ ++ if (!list_empty(&bfqd->dispatch)) { ++ rq = list_first_entry(&bfqd->dispatch, struct request, ++ queuelist); ++ list_del_init(&rq->queuelist); ++ rq->rq_flags &= ~RQF_DISP_LIST; ++ ++ bfq_log(bfqd, ++ "picked %p from dispatch list", rq); ++ bfqq = RQ_BFQQ(rq); ++ ++ if (bfqq) { ++ /* ++ * Increment counters here, because this ++ * dispatch does not follow the standard ++ * dispatch flow (where counters are ++ * incremented) ++ */ ++ bfqq->dispatched++; ++ ++ /* ++ * TESTING: reset DISP_LIST flag, because: 1) ++ * this rq this request has passed through ++ * bfq_prepare_request, 2) then it will have ++ * bfq_finish_requeue_request invoked on it, and 3) in ++ * bfq_finish_requeue_request we use this flag to check ++ * that bfq_finish_requeue_request is not invoked on ++ * requests for which bfq_prepare_request has ++ * been invoked. ++ */ ++ rq->rq_flags &= ~RQF_DISP_LIST; ++ goto inc_in_driver_start_rq; ++ } ++ ++ /* ++ * We exploit the bfq_finish_requeue_request hook to decrement ++ * rq_in_driver, but bfq_finish_requeue_request will not be ++ * invoked on this request. So, to avoid unbalance, ++ * just start this request, without incrementing ++ * rq_in_driver. As a negative consequence, ++ * rq_in_driver is deceptively lower than it should be ++ * while this request is in service. This may cause ++ * bfq_schedule_dispatch to be invoked uselessly. ++ * ++ * As for implementing an exact solution, the ++ * bfq_finish_requeue_request hook, if defined, is probably ++ * invoked also on this request. So, by exploiting ++ * this hook, we could 1) increment rq_in_driver here, ++ * and 2) decrement it in bfq_finish_requeue_request. Such a ++ * solution would let the value of the counter be ++ * always accurate, but it would entail using an extra ++ * interface function. This cost seems higher than the ++ * benefit, being the frequency of non-elevator-private ++ * requests very low. ++ */ ++ goto start_rq; ++ } ++ ++ bfq_log(bfqd, "%d busy queues", bfq_tot_busy_queues(bfqd)); ++ ++ if (bfq_tot_busy_queues(bfqd) == 0) ++ goto exit; ++ ++ /* ++ * Force device to serve one request at a time if ++ * strict_guarantees is true. Forcing this service scheme is ++ * currently the ONLY way to guarantee that the request ++ * service order enforced by the scheduler is respected by a ++ * queueing device. Otherwise the device is free even to make ++ * some unlucky request wait for as long as the device ++ * wishes. ++ * ++ * Of course, serving one request at at time may cause loss of ++ * throughput. ++ */ ++ if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0) ++ goto exit; ++ ++ bfqq = bfq_select_queue(bfqd); ++ if (!bfqq) ++ goto exit; ++ ++ BUG_ON(bfqq == bfqd->in_service_queue && ++ bfqq->entity.budget < bfqq->entity.service); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue && ++ bfq_bfqq_wait_request(bfqq)); ++ ++ rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ if (rq) { ++ inc_in_driver_start_rq: ++ bfqd->rq_in_driver++; ++ start_rq: ++ rq->rq_flags |= RQF_STARTED; ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "%s request %p, rq_in_driver %d", ++ bfq_bfqq_sync(bfqq) ? "sync" : "async", ++ rq, ++ bfqd->rq_in_driver); ++ else ++ bfq_log(bfqd, ++ "request %p from dispatch list, rq_in_driver %d", ++ rq, bfqd->rq_in_driver); ++ } else ++ bfq_log(bfqd, ++ "returned NULL request, rq_in_driver %d", ++ bfqd->rq_in_driver); ++ ++exit: ++ return rq; ++} ++ ++ ++#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP) ++static void bfq_update_dispatch_stats(struct request_queue *q, ++ struct request *rq, ++ struct bfq_queue *in_serv_queue, ++ bool idle_timer_disabled) ++{ ++ struct bfq_queue *bfqq = rq ? RQ_BFQQ(rq) : NULL; ++ ++ if (!idle_timer_disabled && !bfqq) ++ return; ++ ++ /* ++ * rq and bfqq are guaranteed to exist until this function ++ * ends, for the following reasons. First, rq can be ++ * dispatched to the device, and then can be completed and ++ * freed, only after this function ends. Second, rq cannot be ++ * merged (and thus freed because of a merge) any longer, ++ * because it has already started. Thus rq cannot be freed ++ * before this function ends, and, since rq has a reference to ++ * bfqq, the same guarantee holds for bfqq too. ++ * ++ * In addition, the following queue lock guarantees that ++ * bfqq_group(bfqq) exists as well. ++ */ ++ spin_lock_irq(q->queue_lock); ++ if (idle_timer_disabled) ++ /* ++ * Since the idle timer has been disabled, ++ * in_serv_queue contained some request when ++ * __bfq_dispatch_request was invoked above, which ++ * implies that rq was picked exactly from ++ * in_serv_queue. Thus in_serv_queue == bfqq, and is ++ * therefore guaranteed to exist because of the above ++ * arguments. ++ */ ++ bfqg_stats_update_idle_time(bfqq_group(in_serv_queue)); ++ if (bfqq) { ++ struct bfq_group *bfqg = bfqq_group(bfqq); ++ ++ bfqg_stats_update_avg_queue_size(bfqg); ++ bfqg_stats_set_start_empty_time(bfqg); ++ bfqg_stats_update_io_remove(bfqg, rq->cmd_flags); ++ } ++ spin_unlock_irq(q->queue_lock); ++} ++#else ++static inline void bfq_update_dispatch_stats(struct request_queue *q, ++ struct request *rq, ++ struct bfq_queue *in_serv_queue, ++ bool idle_timer_disabled) {} ++#endif ++static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) ++{ ++ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; ++ struct request *rq; ++ struct bfq_queue *in_serv_queue; ++ bool waiting_rq, idle_timer_disabled; ++ ++ spin_lock_irq(&bfqd->lock); ++ ++ in_serv_queue = bfqd->in_service_queue; ++ waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue); ++ ++ rq = __bfq_dispatch_request(hctx); ++ ++ idle_timer_disabled = ++ waiting_rq && !bfq_bfqq_wait_request(in_serv_queue); ++ ++ spin_unlock_irq(&bfqd->lock); ++ ++ bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue, ++ idle_timer_disabled); ++ ++ return rq; ++} ++ ++/* ++ * Task holds one reference to the queue, dropped when task exits. Each rq ++ * in-flight on this queue also holds a reference, dropped when rq is freed. ++ * ++ * Scheduler lock must be held here. Recall not to use bfqq after calling ++ * this function on it. ++ */ ++static void bfq_put_queue(struct bfq_queue *bfqq) ++{ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ struct bfq_group *bfqg = bfqq_group(bfqq); ++#endif ++ ++ assert_spin_locked(&bfqq->bfqd->lock); ++ ++ BUG_ON(bfqq->ref <= 0); ++ ++ if (bfqq->bfqd) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref); ++ ++ bfqq->ref--; ++ if (bfqq->ref) ++ return; ++ ++ BUG_ON(rb_first(&bfqq->sort_list)); ++ BUG_ON(bfqq->allocated != 0); ++ BUG_ON(bfqq->entity.tree); ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ ++ if (!hlist_unhashed(&bfqq->burst_list_node)) { ++ hlist_del_init(&bfqq->burst_list_node); ++ /* ++ * Decrement also burst size after the removal, if the ++ * process associated with bfqq is exiting, and thus ++ * does not contribute to the burst any longer. This ++ * decrement helps filter out false positives of large ++ * bursts, when some short-lived process (often due to ++ * the execution of commands by some service) happens ++ * to start and exit while a complex application is ++ * starting, and thus spawning several processes that ++ * do I/O (and that *must not* be treated as a large ++ * burst, see comments on bfq_handle_burst). ++ * ++ * In particular, the decrement is performed only if: ++ * 1) bfqq is not a merged queue, because, if it is, ++ * then this free of bfqq is not triggered by the exit ++ * of the process bfqq is associated with, but exactly ++ * by the fact that bfqq has just been merged. ++ * 2) burst_size is greater than 0, to handle ++ * unbalanced decrements. Unbalanced decrements may ++ * happen in te following case: bfqq is inserted into ++ * the current burst list--without incrementing ++ * bust_size--because of a split, but the current ++ * burst list is not the burst list bfqq belonged to ++ * (see comments on the case of a split in ++ * bfq_set_request). ++ */ ++ if (bfqq->bic && bfqq->bfqd->burst_size > 0) ++ bfqq->bfqd->burst_size--; ++ } ++ ++ if (bfqq->bfqd) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg); ++ bfqg_and_blkg_put(bfqg); ++#endif ++ kmem_cache_free(bfq_pool, bfqq); ++} ++ ++static void bfq_put_cooperator(struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *__bfqq, *next; ++ ++ /* ++ * If this queue was scheduled to merge with another queue, be ++ * sure to drop the reference taken on that queue (and others in ++ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs. ++ */ ++ __bfqq = bfqq->new_bfqq; ++ while (__bfqq) { ++ if (__bfqq == bfqq) ++ break; ++ next = __bfqq->new_bfqq; ++ bfq_put_queue(__bfqq); ++ __bfqq = next; ++ } ++} ++ ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ if (bfqq == bfqd->in_service_queue) { ++ __bfq_bfqq_expire(bfqd, bfqq); ++ bfq_schedule_dispatch(bfqd); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); /* release process reference */ ++} ++ ++static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync) ++{ ++ struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync); ++ struct bfq_data *bfqd; ++ ++ if (bfqq) ++ bfqd = bfqq->bfqd; /* NULL if scheduler already exited */ ++ ++ if (bfqq && bfqd) { ++ unsigned long flags; ++ ++ spin_lock_irqsave(&bfqd->lock, flags); ++ bfq_exit_bfqq(bfqd, bfqq); ++ bic_set_bfqq(bic, NULL, is_sync); ++ spin_unlock_irqrestore(&bfqd->lock, flags); ++ } ++} ++ ++static void bfq_exit_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ ++ BUG_ON(!bic); ++ bfq_exit_icq_bfqq(bic, true); ++ bfq_exit_icq_bfqq(bic, false); ++} ++ ++/* ++ * Update the entity prio values; note that the new values will not ++ * be used until the next (re)activation. ++ */ ++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ struct task_struct *tsk = current; ++ int ioprio_class; ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ WARN_ON(!bfqd); ++ if (!bfqd) ++ return; ++ ++ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ switch (ioprio_class) { ++ default: ++ dev_err(bfqq->bfqd->queue->backing_dev_info->dev, ++ "bfq: bad prio class %d\n", ioprio_class); ++ case IOPRIO_CLASS_NONE: ++ /* ++ * No prio set, inherit CPU scheduling settings. ++ */ ++ bfqq->new_ioprio = task_nice_ioprio(tsk); ++ bfqq->new_ioprio_class = task_nice_ioclass(tsk); ++ break; ++ case IOPRIO_CLASS_RT: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_RT; ++ break; ++ case IOPRIO_CLASS_BE: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_BE; ++ break; ++ case IOPRIO_CLASS_IDLE: ++ bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE; ++ bfqq->new_ioprio = 7; ++ break; ++ } ++ ++ if (bfqq->new_ioprio >= IOPRIO_BE_NR) { ++ pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n", ++ bfqq->new_ioprio); ++ BUG(); ++ } ++ ++ bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "bic_class %d prio %d class %d", ++ ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class); ++} ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct bfq_queue *bfqq; ++ unsigned long uninitialized_var(flags); ++ int ioprio = bic->icq.ioc->ioprio; ++ ++ /* ++ * This condition may trigger on a newly created bic, be sure to ++ * drop the lock before returning. ++ */ ++ if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) ++ return; ++ ++ bic->ioprio = ioprio; ++ ++ bfqq = bic_to_bfqq(bic, false); ++ if (bfqq) { ++ /* release process reference on this queue */ ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic); ++ bic_set_bfqq(bic, bfqq, false); ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfqq %p %d", ++ bfqq, bfqq->ref); ++ } ++ ++ bfqq = bic_to_bfqq(bic, true); ++ if (bfqq) ++ bfq_set_next_ioprio_data(bfqq, bic); ++} ++ ++static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic, pid_t pid, int is_sync) ++{ ++ RB_CLEAR_NODE(&bfqq->entity.rb_node); ++ INIT_LIST_HEAD(&bfqq->fifo); ++ INIT_HLIST_NODE(&bfqq->burst_list_node); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); ++ ++ bfqq->ref = 0; ++ bfqq->bfqd = bfqd; ++ ++ if (bic) ++ bfq_set_next_ioprio_data(bfqq, bic); ++ ++ if (is_sync) { ++ /* ++ * No need to mark as has_short_ttime if in ++ * idle_class, because no device idling is performed ++ * for queues in idle class ++ */ ++ if (!bfq_class_idle(bfqq)) ++ /* tentatively mark as has_short_ttime */ ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ bfq_mark_bfqq_sync(bfqq); ++ bfq_mark_bfqq_just_created(bfqq); ++ /* ++ * Aggressively inject a lot of service: up to 90%. ++ * This coefficient remains constant during bfqq life, ++ * but this behavior might be changed, after enough ++ * testing and tuning. ++ */ ++ bfqq->inject_coeff = 1; ++ } else ++ bfq_clear_bfqq_sync(bfqq); ++ ++ bfqq->ttime.last_end_request = ktime_get_ns() - (1ULL<<32); ++ ++ bfq_mark_bfqq_IO_bound(bfqq); ++ ++ /* Tentative initial value to trade off between thr and lat */ ++ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3; ++ bfqq->pid = pid; ++ ++ bfqq->wr_coeff = 1; ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now(); ++ bfqq->budget_timeout = bfq_smallest_from_now(); ++ bfqq->split_time = bfq_smallest_from_now(); ++ ++ /* ++ * To not forget the possibly high bandwidth consumed by a ++ * process/queue in the recent past, ++ * bfq_bfqq_softrt_next_start() returns a value at least equal ++ * to the current value of bfqq->soft_rt_next_start (see ++ * comments on bfq_bfqq_softrt_next_start). Set ++ * soft_rt_next_start to now, to mean that bfqq has consumed ++ * no bandwidth so far. ++ */ ++ bfqq->soft_rt_next_start = jiffies; ++ ++ /* first request is almost certainly seeky */ ++ bfqq->seek_history = 1; ++} ++ ++static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ int ioprio_class, int ioprio) ++{ ++ switch (ioprio_class) { ++ case IOPRIO_CLASS_RT: ++ return &bfqg->async_bfqq[0][ioprio]; ++ case IOPRIO_CLASS_NONE: ++ ioprio = IOPRIO_NORM; ++ /* fall through */ ++ case IOPRIO_CLASS_BE: ++ return &bfqg->async_bfqq[1][ioprio]; ++ case IOPRIO_CLASS_IDLE: ++ return &bfqg->async_idle_bfqq; ++ default: ++ BUG(); ++ } ++} ++ ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic) ++{ ++ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ struct bfq_queue **async_bfqq = NULL; ++ struct bfq_queue *bfqq; ++ struct bfq_group *bfqg; ++ ++ rcu_read_lock(); ++ ++ bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio)); ++ if (!bfqg) { ++ bfqq = &bfqd->oom_bfqq; ++ goto out; ++ } ++ ++ if (!is_sync) { ++ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, ++ ioprio); ++ bfqq = *async_bfqq; ++ if (bfqq) ++ goto out; ++ } ++ ++ bfqq = kmem_cache_alloc_node(bfq_pool, ++ GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN, ++ bfqd->queue->node); ++ ++ if (bfqq) { ++ bfq_init_bfqq(bfqd, bfqq, bic, current->pid, ++ is_sync); ++ bfq_init_entity(&bfqq->entity, bfqg); ++ bfq_log_bfqq(bfqd, bfqq, "allocated"); ++ } else { ++ bfqq = &bfqd->oom_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); ++ goto out; ++ } ++ ++ /* ++ * Pin the queue now that it's allocated, scheduler exit will ++ * prune it. ++ */ ++ if (async_bfqq) { ++ bfqq->ref++; /* ++ * Extra group reference, w.r.t. sync ++ * queue. This extra reference is removed ++ * only if bfqq->bfqg disappears, to ++ * guarantee that this queue is not freed ++ * until its group goes away. ++ */ ++ bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d", ++ bfqq, bfqq->ref); ++ *async_bfqq = bfqq; ++ } ++ ++out: ++ bfqq->ref++; /* get a process reference to this queue */ ++ bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref); ++ rcu_read_unlock(); ++ return bfqq; ++} ++ ++static void bfq_update_io_thinktime(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_ttime *ttime = &bfqq->ttime; ++ u64 elapsed = ktime_get_ns() - bfqq->ttime.last_end_request; ++ ++ elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle); ++ ++ ttime->ttime_samples = (7*bfqq->ttime.ttime_samples + 256) / 8; ++ ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8); ++ ttime->ttime_mean = div64_ul(ttime->ttime_total + 128, ++ ttime->ttime_samples); ++} ++ ++static void ++bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ bfqq->seek_history <<= 1; ++ bfqq->seek_history |= BFQ_RQ_SEEKY(bfqd, bfqq->last_request_pos, rq); ++} ++ ++static void bfq_update_has_short_ttime(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ bool has_short_ttime = true; ++ ++ /* ++ * No need to update has_short_ttime if bfqq is async or in ++ * idle io prio class, or if bfq_slice_idle is zero, because ++ * no device idling is performed for bfqq in this case. ++ */ ++ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) || ++ bfqd->bfq_slice_idle == 0) ++ return; ++ ++ /* Idle window just restored, statistics are meaningless. */ ++ if (time_is_after_eq_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) ++ return; ++ ++ /* Think time is infinite if no process is linked to ++ * bfqq. Otherwise check average think time to ++ * decide whether to mark as has_short_ttime ++ */ ++ if (atomic_read(&bic->icq.ioc->active_ref) == 0 || ++ (bfq_sample_valid(bfqq->ttime.ttime_samples) && ++ bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle)) ++ has_short_ttime = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d", ++ has_short_ttime); ++ ++ if (has_short_ttime) ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ else ++ bfq_clear_bfqq_has_short_ttime(bfqq); ++} ++ ++/* ++ * Called when a new fs request (rq) is added to bfqq. Check if there's ++ * something we should do about it. ++ */ ++static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ struct bfq_io_cq *bic = RQ_BIC(rq); ++ ++ if (rq->cmd_flags & REQ_META) ++ bfqq->meta_pending++; ++ ++ bfq_update_io_thinktime(bfqd, bfqq); ++ bfq_update_has_short_ttime(bfqd, bfqq, bic); ++ bfq_update_io_seektime(bfqd, bfqq, rq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "has_short_ttime=%d (seeky %d)", ++ bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq)); ++ ++ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ ++ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { ++ bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 && ++ blk_rq_sectors(rq) < 32; ++ bool budget_timeout = bfq_bfqq_budget_timeout(bfqq); ++ ++ /* ++ * There is just this request queued: if ++ * - the request is small, and ++ * - we are idling to boost throughput, and ++ * - the queue is not to be expired, ++ * then just exit. ++ * ++ * In this way, if the device is being idled to wait ++ * for a new request from the in-service queue, we ++ * avoid unplugging the device and committing the ++ * device to serve just a small request. In contrast ++ * we wait for the block layer to decide when to ++ * unplug the device: hopefully, new requests will be ++ * merged to this one quickly, then the device will be ++ * unplugged and larger requests will be dispatched. ++ */ ++ if (small_req && idling_boosts_thr_without_issues(bfqd, bfqq) && ++ !budget_timeout) ++ return; ++ ++ /* ++ * A large enough request arrived, or idling is being ++ * performed to preserve service guarantees, or ++ * finally the queue is to be expired: in all these ++ * cases disk idling is to be stopped, so clear ++ * wait_request flag and reset timer. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ hrtimer_try_to_cancel(&bfqd->idle_slice_timer); ++ ++ /* ++ * The queue is not empty, because a new request just ++ * arrived. Hence we can safely expire the queue, in ++ * case of budget timeout, without risking that the ++ * timestamps of the queue are not updated correctly. ++ * See [1] for more details. ++ */ ++ if (budget_timeout) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ } ++} ++ ++/* returns true if it causes the idle timer to be disabled */ ++static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq; ++ bool waiting, idle_timer_disabled = false; ++ BUG_ON(!bfqq); ++ ++ assert_spin_locked(&bfqd->lock); ++ ++ bfq_log_bfqq(bfqd, bfqq, "rq %p bfqq %p", rq, bfqq); ++ ++ /* ++ * An unplug may trigger a requeue of a request from the device ++ * driver: make sure we are in process context while trying to ++ * merge two bfq_queues. ++ */ ++ if (!in_interrupt()) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true); ++ if (new_bfqq) { ++ BUG_ON(bic_to_bfqq(RQ_BIC(rq), 1) != bfqq); ++ /* ++ * Release the request's reference to the old bfqq ++ * and make sure one is taken to the shared queue. ++ */ ++ new_bfqq->allocated++; ++ bfqq->allocated--; ++ bfq_log_bfqq(bfqd, bfqq, ++ "new allocated %d", bfqq->allocated); ++ bfq_log_bfqq(bfqd, new_bfqq, ++ "new_bfqq new allocated %d", ++ bfqq->allocated); ++ ++ new_bfqq->ref++; ++ /* ++ * If the bic associated with the process ++ * issuing this request still points to bfqq ++ * (and thus has not been already redirected ++ * to new_bfqq or even some other bfq_queue), ++ * then complete the merge and redirect it to ++ * new_bfqq. ++ */ ++ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq) ++ bfq_merge_bfqqs(bfqd, RQ_BIC(rq), ++ bfqq, new_bfqq); ++ ++ bfq_clear_bfqq_just_created(bfqq); ++ /* ++ * rq is about to be enqueued into new_bfqq, ++ * release rq reference on bfqq ++ */ ++ bfq_put_queue(bfqq); ++ rq->elv.priv[1] = new_bfqq; ++ bfqq = new_bfqq; ++ } ++ } ++ ++ waiting = bfqq && bfq_bfqq_wait_request(bfqq); ++ bfq_add_request(rq); ++ idle_timer_disabled = waiting && !bfq_bfqq_wait_request(bfqq); ++ ++ rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; ++ list_add_tail(&rq->queuelist, &bfqq->fifo); ++ ++ bfq_rq_enqueued(bfqd, bfqq, rq); ++ ++ return idle_timer_disabled; ++} ++ ++#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP) ++static void bfq_update_insert_stats(struct request_queue *q, ++ struct bfq_queue *bfqq, ++ bool idle_timer_disabled, ++ unsigned int cmd_flags) ++{ ++ if (!bfqq) ++ return; ++ ++ /* ++ * bfqq still exists, because it can disappear only after ++ * either it is merged with another queue, or the process it ++ * is associated with exits. But both actions must be taken by ++ * the same process currently executing this flow of ++ * instructions. ++ * ++ * In addition, the following queue lock guarantees that ++ * bfqq_group(bfqq) exists as well. ++ */ ++ spin_lock_irq(q->queue_lock); ++ bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags); ++ if (idle_timer_disabled) ++ bfqg_stats_update_idle_time(bfqq_group(bfqq)); ++ spin_unlock_irq(q->queue_lock); ++} ++#else ++static inline void bfq_update_insert_stats(struct request_queue *q, ++ struct bfq_queue *bfqq, ++ bool idle_timer_disabled, ++ unsigned int cmd_flags) {} ++#endif ++ ++static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, ++ bool at_head) ++{ ++ struct request_queue *q = hctx->queue; ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq; ++ bool idle_timer_disabled = false; ++ unsigned int cmd_flags; ++ ++ spin_lock_irq(&bfqd->lock); ++ if (blk_mq_sched_try_insert_merge(q, rq)) { ++ spin_unlock_irq(&bfqd->lock); ++ return; ++ } ++ ++ spin_unlock_irq(&bfqd->lock); ++ ++ blk_mq_sched_request_inserted(rq); ++ ++ spin_lock_irq(&bfqd->lock); ++ ++ bfqq = bfq_init_rq(rq); ++ BUG_ON(!bfqq && !(at_head || blk_rq_is_passthrough(rq))); ++ BUG_ON(bfqq && bic_to_bfqq(RQ_BIC(rq), rq_is_sync(rq)) != bfqq); ++ ++ if (at_head || blk_rq_is_passthrough(rq)) { ++ if (at_head) ++ list_add(&rq->queuelist, &bfqd->dispatch); ++ else ++ list_add_tail(&rq->queuelist, &bfqd->dispatch); ++ ++ rq->rq_flags |= RQF_DISP_LIST; ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "%p in disp: at_head %d", ++ rq, at_head); ++ else ++ bfq_log(bfqd, ++ "%p in disp: at_head %d", ++ rq, at_head); ++ } else { /* bfqq is assumed to be non null here */ ++ BUG_ON(!bfqq); ++ BUG_ON(!(rq->rq_flags & RQF_GOT)); ++ rq->rq_flags &= ~RQF_GOT; ++ ++ idle_timer_disabled = __bfq_insert_request(bfqd, rq); ++ /* ++ * Update bfqq, because, if a queue merge has occurred ++ * in __bfq_insert_request, then rq has been ++ * redirected into a new queue. ++ */ ++ bfqq = RQ_BFQQ(rq); ++ ++ if (rq_mergeable(rq)) { ++ elv_rqhash_add(q, rq); ++ if (!q->last_merge) ++ q->last_merge = rq; ++ } ++ } ++ ++ /* ++ * Cache cmd_flags before releasing scheduler lock, because rq ++ * may disappear afterwards (for example, because of a request ++ * merge). ++ */ ++ cmd_flags = rq->cmd_flags; ++ ++ spin_unlock_irq(&bfqd->lock); ++ bfq_update_insert_stats(q, bfqq, idle_timer_disabled, ++ cmd_flags); ++} ++ ++static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, ++ struct list_head *list, bool at_head) ++{ ++ while (!list_empty(list)) { ++ struct request *rq; ++ ++ rq = list_first_entry(list, struct request, queuelist); ++ list_del_init(&rq->queuelist); ++ bfq_insert_request(hctx, rq, at_head); ++ } ++} ++ ++static void bfq_update_hw_tag(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ ++ bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver, ++ bfqd->rq_in_driver); ++ ++ if (bfqd->hw_tag == 1) ++ return; ++ ++ /* ++ * This sample is valid if the number of outstanding requests ++ * is large enough to allow a queueing behavior. Note that the ++ * sum is not exact, as it's not taking into account deactivated ++ * requests. ++ */ ++ if (bfqd->rq_in_driver + bfqd->queued <= BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ /* ++ * If active queue hasn't enough requests and can idle, bfq might not ++ * dispatch sufficient requests to hardware. Don't zero hw_tag in this ++ * case ++ */ ++ if (bfqq && bfq_bfqq_has_short_ttime(bfqq) && ++ bfqq->dispatched + bfqq->queued[0] + bfqq->queued[1] < ++ BFQ_HW_QUEUE_THRESHOLD && bfqd->rq_in_driver < BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES) ++ return; ++ ++ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD; ++ bfqd->max_rq_in_driver = 0; ++ bfqd->hw_tag_samples = 0; ++} ++ ++static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd) ++{ ++ u64 now_ns; ++ u32 delta_us; ++ ++ bfq_update_hw_tag(bfqd); ++ ++ BUG_ON(!bfqd->rq_in_driver); ++ BUG_ON(!bfqq->dispatched); ++ bfqd->rq_in_driver--; ++ bfqq->dispatched--; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "new disp %d, new rq_in_driver %d", ++ bfqq->dispatched, bfqd->rq_in_driver); ++ ++ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ /* ++ * Set budget_timeout (which we overload to store the ++ * time at which the queue remains with no backlog and ++ * no outstanding request; used by the weight-raising ++ * mechanism). ++ */ ++ bfqq->budget_timeout = jiffies; ++ ++ bfq_weights_tree_remove(bfqd, bfqq); ++ } ++ ++ now_ns = ktime_get_ns(); ++ ++ bfqq->ttime.last_end_request = now_ns; ++ ++ /* ++ * Using us instead of ns, to get a reasonable precision in ++ * computing rate in next check. ++ */ ++ delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "delta %uus/%luus max_size %u rate %llu/%llu", ++ delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size, ++ delta_us > 0 ? ++ (USEC_PER_SEC* ++ (u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us)) ++ >>BFQ_RATE_SHIFT : ++ (USEC_PER_SEC* ++ (u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT, ++ (USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT); ++ ++ /* ++ * If the request took rather long to complete, and, according ++ * to the maximum request size recorded, this completion latency ++ * implies that the request was certainly served at a very low ++ * rate (less than 1M sectors/sec), then the whole observation ++ * interval that lasts up to this time instant cannot be a ++ * valid time interval for computing a new peak rate. Invoke ++ * bfq_update_rate_reset to have the following three steps ++ * taken: ++ * - close the observation interval at the last (previous) ++ * request dispatch or completion ++ * - compute rate, if possible, for that observation interval ++ * - reset to zero samples, which will trigger a proper ++ * re-initialization of the observation interval on next ++ * dispatch ++ */ ++ if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC && ++ (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us < ++ 1UL<<(BFQ_RATE_SHIFT - 10)) ++ bfq_update_rate_reset(bfqd, NULL); ++ bfqd->last_completion = now_ns; ++ ++ /* ++ * If we are waiting to discover whether the request pattern ++ * of the task associated with the queue is actually ++ * isochronous, and both requisites for this condition to hold ++ * are now satisfied, then compute soft_rt_next_start (see the ++ * comments on the function bfq_bfqq_softrt_next_start()). We ++ * do not compute soft_rt_next_start if bfqq is in interactive ++ * weight raising (see the comments in bfq_bfqq_expire() for ++ * an explanation). We schedule this delayed update when bfqq ++ * expires, if it still has in-flight requests. ++ */ ++ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list) && ++ bfqq->wr_coeff != bfqd->bfq_wr_coeff) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ ++ /* ++ * If this is the in-service queue, check if it needs to be expired, ++ * or if we want to idle in case it has no pending requests. ++ */ ++ if (bfqd->in_service_queue == bfqq) { ++ if (bfq_bfqq_must_idle(bfqq)) { ++ if (bfqq->dispatched == 0) ++ bfq_arm_slice_timer(bfqd); ++ /* ++ * If we get here, we do not expire bfqq, even ++ * if bfqq was in budget timeout or had no ++ * more requests (as controlled in the next ++ * conditional instructions). The reason for ++ * not expiring bfqq is as follows. ++ * ++ * Here bfqq->dispatched > 0 holds, but ++ * bfq_bfqq_must_idle() returned true. This ++ * implies that, even if no request arrives ++ * for bfqq before bfqq->dispatched reaches 0, ++ * bfqq will, however, not be expired on the ++ * completion event that causes bfqq->dispatch ++ * to reach zero. In contrast, on this event, ++ * bfqq will start enjoying device idling ++ * (I/O-dispatch plugging). ++ * ++ * But, if we expired bfqq here, bfqq would ++ * not have the chance to enjoy device idling ++ * when bfqq->dispatched finally reaches ++ * zero. This would expose bfqq to violation ++ * of its reserved service guarantees. ++ */ ++ return; ++ } else if (bfq_may_expire_for_budg_timeout(bfqq)) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ else if (RB_EMPTY_ROOT(&bfqq->sort_list) && ++ (bfqq->dispatched == 0 || ++ !bfq_better_to_idle(bfqq))) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_NO_MORE_REQUESTS); ++ } ++} ++ ++static void bfq_finish_requeue_request_body(struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "allocated %d", bfqq->allocated); ++ BUG_ON(!bfqq->allocated); ++ bfqq->allocated--; ++ ++ bfq_put_queue(bfqq); ++} ++ ++/* ++ * Handle either a requeue or a finish for rq. The things to do are ++ * the same in both cases: all references to rq are to be dropped. In ++ * particular, rq is considered completed from the point of view of ++ * the scheduler. ++ */ ++static void bfq_finish_requeue_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq; ++ struct bfq_data *bfqd; ++ struct bfq_io_cq *bic; ++ ++ BUG_ON(!rq); ++ ++ bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * Requeue and finish hooks are invoked in blk-mq without ++ * checking whether the involved request is actually still ++ * referenced in the scheduler. To handle this fact, the ++ * following two checks make this function exit in case of ++ * spurious invocations, for which there is nothing to do. ++ * ++ * First, check whether rq has nothing to do with an elevator. ++ */ ++ if (unlikely(!(rq->rq_flags & RQF_ELVPRIV))) ++ return; ++ ++ /* ++ * rq either is not associated with any icq, or is an already ++ * requeued request that has not (yet) been re-inserted into ++ * a bfq_queue. ++ */ ++ if (!rq->elv.icq || !bfqq) ++ return; ++ ++ bic = RQ_BIC(rq); ++ BUG_ON(!bic); ++ ++ bfqd = bfqq->bfqd; ++ BUG_ON(!bfqd); ++ ++ if (rq->rq_flags & RQF_DISP_LIST) { ++ pr_crit("putting disp rq %p for %d", rq, bfqq->pid); ++ BUG(); ++ } ++ BUG_ON(rq->rq_flags & RQF_QUEUED); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "putting rq %p with %u sects left, STARTED %d", ++ rq, blk_rq_sectors(rq), ++ rq->rq_flags & RQF_STARTED); ++ ++ if (rq->rq_flags & RQF_STARTED) ++ bfqg_stats_update_completion(bfqq_group(bfqq), ++ rq->start_time_ns, ++ rq->io_start_time_ns, ++ rq->cmd_flags); ++ ++ WARN_ON(blk_rq_sectors(rq) == 0 && !(rq->rq_flags & RQF_STARTED)); ++ ++ if (likely(rq->rq_flags & RQF_STARTED)) { ++ unsigned long flags; ++ ++ spin_lock_irqsave(&bfqd->lock, flags); ++ ++ bfq_completed_request(bfqq, bfqd); ++ bfq_finish_requeue_request_body(bfqq); ++ ++ spin_unlock_irqrestore(&bfqd->lock, flags); ++ } else { ++ /* ++ * Request rq may be still/already in the scheduler, ++ * in which case we need to remove it (this should ++ * never happen in case of requeue). And we cannot ++ * defer such a check and removal, to avoid ++ * inconsistencies in the time interval from the end ++ * of this function to the start of the deferred work. ++ * This situation seems to occur only in process ++ * context, as a consequence of a merge. In the ++ * current version of the code, this implies that the ++ * lock is held. ++ */ ++ BUG_ON(in_interrupt()); ++ ++ assert_spin_locked(&bfqd->lock); ++ if (!RB_EMPTY_NODE(&rq->rb_node)) { ++ bfq_remove_request(rq->q, rq); ++ bfqg_stats_update_io_remove(bfqq_group(bfqq), ++ rq->cmd_flags); ++ } ++ bfq_finish_requeue_request_body(bfqq); ++ } ++ ++ /* ++ * Reset private fields. In case of a requeue, this allows ++ * this function to correctly do nothing if it is spuriously ++ * invoked again on this same request (see the check at the ++ * beginning of the function). Probably, a better general ++ * design would be to prevent blk-mq from invoking the requeue ++ * or finish hooks of an elevator, for a request that is not ++ * referred by that elevator. ++ * ++ * Resetting the following fields would break the ++ * request-insertion logic if rq is re-inserted into a bfq ++ * internal queue, without a re-preparation. Here we assume ++ * that re-insertions of requeued requests, without ++ * re-preparation, can happen only for pass_through or at_head ++ * requests (which are not re-inserted into bfq internal ++ * queues). ++ */ ++ rq->elv.priv[0] = NULL; ++ rq->elv.priv[1] = NULL; ++} ++ ++/* ++ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this ++ * was the last process referring to that bfqq. ++ */ ++static struct bfq_queue * ++bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue"); ++ ++ if (bfqq_process_refs(bfqq) == 1) { ++ bfqq->pid = current->pid; ++ bfq_clear_bfqq_coop(bfqq); ++ bfq_clear_bfqq_split_coop(bfqq); ++ return bfqq; ++ } ++ ++ bic_set_bfqq(bic, NULL, 1); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); ++ return NULL; ++} ++ ++static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, ++ struct bio *bio, ++ bool split, bool is_sync, ++ bool *new_queue) ++{ ++ struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync); ++ ++ if (likely(bfqq && bfqq != &bfqd->oom_bfqq)) ++ return bfqq; ++ ++ if (new_queue) ++ *new_queue = true; ++ ++ if (bfqq) ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); ++ ++ bic_set_bfqq(bic, bfqq, is_sync); ++ if (split && is_sync) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "get_request: was_in_list %d " ++ "was_in_large_burst %d " ++ "large burst in progress %d", ++ bic->was_in_burst_list, ++ bic->saved_in_large_burst, ++ bfqd->large_burst); ++ ++ if ((bic->was_in_burst_list && bfqd->large_burst) || ++ bic->saved_in_large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "get_request: marking in " ++ "large burst"); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ } else { ++ bfq_log_bfqq(bfqd, bfqq, ++ "get_request: clearing in " ++ "large burst"); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ if (bic->was_in_burst_list) ++ /* ++ * If bfqq was in the current ++ * burst list before being ++ * merged, then we have to add ++ * it back. And we do not need ++ * to increase burst_size, as ++ * we did not decrement ++ * burst_size when we removed ++ * bfqq from the burst list as ++ * a consequence of a merge ++ * (see comments in ++ * bfq_put_queue). In this ++ * respect, it would be rather ++ * costly to know whether the ++ * current burst list is still ++ * the same burst list from ++ * which bfqq was removed on ++ * the merge. To avoid this ++ * cost, if bfqq was in a ++ * burst list, then we add ++ * bfqq to the current burst ++ * list without any further ++ * check. This can cause ++ * inappropriate insertions, ++ * but rarely enough to not ++ * harm the detection of large ++ * bursts significantly. ++ */ ++ hlist_add_head(&bfqq->burst_list_node, ++ &bfqd->burst_list); ++ } ++ bfqq->split_time = jiffies; ++ } ++ ++ return bfqq; ++} ++ ++/* ++ * Only reset private fields. The actual request preparation will be ++ * performed by bfq_init_rq, when rq is either inserted or merged. See ++ * comments on bfq_init_rq for the reason behind this delayed ++ * preparation. ++*/ ++static void bfq_prepare_request(struct request *rq, struct bio *bio) ++{ ++ /* ++ * Regardless of whether we have an icq attached, we have to ++ * clear the scheduler pointers, as they might point to ++ * previously allocated bic/bfqq structs. ++ */ ++ rq->elv.priv[0] = rq->elv.priv[1] = NULL; ++} ++ ++/* ++ * If needed, init rq, allocate bfq data structures associated with ++ * rq, and increment reference counters in the destination bfq_queue ++ * for rq. Return the destination bfq_queue for rq, or NULL is rq is ++ * not associated with any bfq_queue. ++ * ++ * This function is invoked by the functions that perform rq insertion ++ * or merging. One may have expected the above preparation operations ++ * to be performed in bfq_prepare_request, and not delayed to when rq ++ * is inserted or merged. The rationale behind this delayed ++ * preparation is that, after the prepare_request hook is invoked for ++ * rq, rq may still be transformed into a request with no icq, i.e., a ++ * request not associated with any queue. No bfq hook is invoked to ++ * signal this tranformation. As a consequence, should these ++ * preparation operations be performed when the prepare_request hook ++ * is invoked, and should rq be transformed one moment later, bfq ++ * would end up in an inconsistent state, because it would have ++ * incremented some queue counters for an rq destined to ++ * transformation, without any chance to correctly lower these ++ * counters back. In contrast, no transformation can still happen for ++ * rq after rq has been inserted or merged. So, it is safe to execute ++ * these preparation operations when rq is finally inserted or merged. ++ */ ++static struct bfq_queue *bfq_init_rq(struct request *rq) ++{ ++ struct request_queue *q = rq->q; ++ struct bio *bio = rq->bio; ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic; ++ const int is_sync = rq_is_sync(rq); ++ struct bfq_queue *bfqq; ++ bool bfqq_already_existing = false, split = false; ++ bool new_queue = false; ++ ++ if (unlikely(!rq->elv.icq)) ++ return NULL; ++ ++ /* ++ * Assuming that elv.priv[1] is set only if everything is set ++ * for this rq. This holds true, because this function is ++ * invoked only for insertion or merging, and, after such ++ * events, a request cannot be manipulated any longer before ++ * being removed from bfq. ++ */ ++ if (rq->elv.priv[1]) { ++ BUG_ON(!(rq->rq_flags & RQF_ELVPRIV)); ++ return rq->elv.priv[1]; ++ } ++ ++ bic = icq_to_bic(rq->elv.icq); ++ ++ bfq_check_ioprio_change(bic, bio); ++ ++ bfq_bic_update_cgroup(bic, bio); ++ ++ bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync, ++ &new_queue); ++ ++ if (likely(!new_queue)) { ++ /* If the queue was seeky for too long, break it apart. */ ++ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { ++ BUG_ON(!is_sync); ++ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); ++ ++ /* Update bic before losing reference to bfqq */ ++ if (bfq_bfqq_in_large_burst(bfqq)) ++ bic->saved_in_large_burst = true; ++ ++ bfqq = bfq_split_bfqq(bic, bfqq); ++ split = true; ++ ++ if (!bfqq) ++ bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, ++ true, is_sync, ++ NULL); ++ else ++ bfqq_already_existing = true; ++ ++ BUG_ON(!bfqq); ++ BUG_ON(bfqq == &bfqd->oom_bfqq); ++ } ++ } ++ ++ bfqq->allocated++; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "new allocated %d", bfqq->allocated); ++ ++ bfqq->ref++; ++ bfq_log_bfqq(bfqd, bfqq, "%p: bfqq %p, %d", rq, bfqq, bfqq->ref); ++ ++ rq->elv.priv[0] = bic; ++ rq->elv.priv[1] = bfqq; ++ rq->rq_flags &= ~RQF_DISP_LIST; ++ ++ /* ++ * If a bfq_queue has only one process reference, it is owned ++ * by only this bic: we can then set bfqq->bic = bic. in ++ * addition, if the queue has also just been split, we have to ++ * resume its state. ++ */ ++ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { ++ bfqq->bic = bic; ++ if (split) { ++ /* ++ * The queue has just been split from a shared ++ * queue: restore the idle window and the ++ * possible weight raising period. ++ */ ++ bfq_bfqq_resume_state(bfqq, bfqd, bic, ++ bfqq_already_existing); ++ } ++ } ++ ++ if (unlikely(bfq_bfqq_just_created(bfqq))) ++ bfq_handle_burst(bfqd, bfqq); ++ ++ rq->rq_flags |= RQF_GOT; ++ ++ return bfqq; ++} ++ ++static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ enum bfqq_expiration reason; ++ unsigned long flags; ++ ++ BUG_ON(!bfqd); ++ spin_lock_irqsave(&bfqd->lock, flags); ++ ++ bfq_log_bfqq(bfqd, bfqq, "handling slice_timer expiration"); ++ bfq_clear_bfqq_wait_request(bfqq); ++ ++ if (bfqq != bfqd->in_service_queue) { ++ spin_unlock_irqrestore(&bfqd->lock, flags); ++ return; ++ } ++ ++ if (bfq_bfqq_budget_timeout(bfqq)) ++ /* ++ * Also here the queue can be safely expired ++ * for budget timeout without wasting ++ * guarantees ++ */ ++ reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0) ++ /* ++ * The queue may not be empty upon timer expiration, ++ * because we may not disable the timer when the ++ * first request of the in-service queue arrives ++ * during disk idling. ++ */ ++ reason = BFQ_BFQQ_TOO_IDLE; ++ else ++ goto schedule_dispatch; ++ ++ bfq_bfqq_expire(bfqd, bfqq, true, reason); ++ ++schedule_dispatch: ++ spin_unlock_irqrestore(&bfqd->lock, flags); ++ bfq_schedule_dispatch(bfqd); ++} ++ ++/* ++ * Handler of the expiration of the timer running if the in-service queue ++ * is idling inside its time slice. ++ */ ++static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer) ++{ ++ struct bfq_data *bfqd = container_of(timer, struct bfq_data, ++ idle_slice_timer); ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ ++ bfq_log(bfqd, "expired"); ++ ++ /* ++ * Theoretical race here: the in-service queue can be NULL or ++ * different from the queue that was idling if a new request ++ * arrives for the current queue and there is a full dispatch ++ * cycle that changes the in-service queue. This can hardly ++ * happen, but in the worst case we just expire a queue too ++ * early. ++ */ ++ if (bfqq) ++ bfq_idle_slice_timer_body(bfqq); ++ ++ return HRTIMER_NORESTART; ++} ++ ++static void __bfq_put_async_bfqq(struct bfq_data *bfqd, ++ struct bfq_queue **bfqq_ptr) ++{ ++ struct bfq_group *root_group = bfqd->root_group; ++ struct bfq_queue *bfqq = *bfqq_ptr; ++ ++ bfq_log(bfqd, "%p", bfqq); ++ if (bfqq) { ++ bfq_bfqq_move(bfqd, bfqq, root_group); ++ bfq_log_bfqq(bfqd, bfqq, "putting %p, %d", ++ bfqq, bfqq->ref); ++ bfq_put_queue(bfqq); ++ *bfqq_ptr = NULL; ++ } ++} ++ ++/* ++ * Release all the bfqg references to its async queues. If we are ++ * deallocating the group these queues may still contain requests, so ++ * we reparent them to the root cgroup (i.e., the only one that will ++ * exist for sure until all the requests on a device are gone). ++ */ ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]); ++ ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); ++} ++ ++/* ++ * See the comments on bfq_limit_depth for the purpose of ++ * the depths set in the function. Return minimum shallow depth we'll use. ++ */ ++static unsigned int bfq_update_depths(struct bfq_data *bfqd, ++ struct sbitmap_queue *bt) ++{ ++ unsigned int i, j, min_shallow = UINT_MAX; ++ ++ /* ++ * In-word depths if no bfq_queue is being weight-raised: ++ * leaving 25% of tags only for sync reads. ++ * ++ * In next formulas, right-shift the value ++ * (1U<<bt->sb.shift), instead of computing directly ++ * (1U<<(bt->sb.shift - something)), to be robust against ++ * any possible value of bt->sb.shift, without having to ++ * limit 'something'. ++ */ ++ /* no more than 50% of tags for async I/O */ ++ bfqd->word_depths[0][0] = max((1U<<bt->sb.shift)>>1, 1U); ++ /* ++ * no more than 75% of tags for sync writes (25% extra tags ++ * w.r.t. async I/O, to prevent async I/O from starving sync ++ * writes) ++ */ ++ bfqd->word_depths[0][1] = max(((1U<<bt->sb.shift) * 3)>>2, 1U); ++ ++ /* ++ * In-word depths in case some bfq_queue is being weight- ++ * raised: leaving ~63% of tags for sync reads. This is the ++ * highest percentage for which, in our tests, application ++ * start-up times didn't suffer from any regression due to tag ++ * shortage. ++ */ ++ /* no more than ~18% of tags for async I/O */ ++ bfqd->word_depths[1][0] = max(((1U<<bt->sb.shift) * 3)>>4, 1U); ++ /* no more than ~37% of tags for sync writes (~20% extra tags) */ ++ bfqd->word_depths[1][1] = max(((1U<<bt->sb.shift) * 6)>>4, 1U); ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < 2; j++) ++ min_shallow = min(min_shallow, bfqd->word_depths[i][j]); ++ ++ return min_shallow; ++} ++ ++static void bfq_depth_updated(struct blk_mq_hw_ctx *hctx) ++{ ++ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; ++ struct blk_mq_tags *tags = hctx->sched_tags; ++ unsigned int min_shallow; ++ ++ min_shallow = bfq_update_depths(bfqd, &tags->bitmap_tags); ++ sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, min_shallow); ++} ++ ++static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index) ++{ ++ bfq_depth_updated(hctx); ++ return 0; ++} ++ ++static void bfq_exit_queue(struct elevator_queue *e) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ struct bfq_queue *bfqq, *n; ++ ++ bfq_log(bfqd, "starting ..."); ++ ++ hrtimer_cancel(&bfqd->idle_slice_timer); ++ ++ BUG_ON(bfqd->in_service_queue); ++ BUG_ON(!list_empty(&bfqd->active_list)); ++ ++ spin_lock_irq(&bfqd->lock); ++ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) ++ bfq_deactivate_bfqq(bfqd, bfqq, false, false); ++ spin_unlock_irq(&bfqd->lock); ++ ++ hrtimer_cancel(&bfqd->idle_slice_timer); ++ ++ BUG_ON(hrtimer_active(&bfqd->idle_slice_timer)); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ /* release oom-queue reference to root group */ ++ bfqg_and_blkg_put(bfqd->root_group); ++ ++ blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq); ++#else ++ spin_lock_irq(&bfqd->lock); ++ bfq_put_async_queues(bfqd, bfqd->root_group); ++ kfree(bfqd->root_group); ++ spin_unlock_irq(&bfqd->lock); ++#endif ++ ++ bfq_log(bfqd, "finished ..."); ++ kfree(bfqd); ++} ++ ++static void bfq_init_root_group(struct bfq_group *root_group, ++ struct bfq_data *bfqd) ++{ ++ int i; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ root_group->entity.parent = NULL; ++ root_group->my_entity = NULL; ++ root_group->bfqd = bfqd; ++#endif ++ root_group->rq_pos_tree = RB_ROOT; ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ root_group->sched_data.bfq_class_idle_last_service = jiffies; ++} ++ ++static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) ++{ ++ struct bfq_data *bfqd; ++ struct elevator_queue *eq; ++ ++ eq = elevator_alloc(q, e); ++ if (!eq) ++ return -ENOMEM; ++ ++ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); ++ if (!bfqd) { ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++ } ++ eq->elevator_data = bfqd; ++ ++ spin_lock_irq(q->queue_lock); ++ q->elevator = eq; ++ spin_unlock_irq(q->queue_lock); ++ ++ /* ++ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues. ++ * Grab a permanent reference to it, so that the normal code flow ++ * will not attempt to free it. ++ */ ++ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); ++ bfqd->oom_bfqq.ref++; ++ bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; ++ bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; ++ bfqd->oom_bfqq.entity.new_weight = ++ bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); ++ ++ /* oom_bfqq does not participate to bursts */ ++ bfq_clear_bfqq_just_created(&bfqd->oom_bfqq); ++ /* ++ * Trigger weight initialization, according to ioprio, at the ++ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio ++ * class won't be changed any more. ++ */ ++ bfqd->oom_bfqq.entity.prio_changed = 1; ++ ++ bfqd->queue = q; ++ INIT_LIST_HEAD(&bfqd->dispatch); ++ ++ hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC, ++ HRTIMER_MODE_REL); ++ bfqd->idle_slice_timer.function = bfq_idle_slice_timer; ++ ++ bfqd->queue_weights_tree = RB_ROOT; ++ bfqd->num_groups_with_pending_reqs = 0; ++ ++ INIT_LIST_HEAD(&bfqd->active_list); ++ INIT_LIST_HEAD(&bfqd->idle_list); ++ INIT_HLIST_HEAD(&bfqd->burst_list); ++ ++ bfqd->hw_tag = -1; ++ ++ bfqd->bfq_max_budget = bfq_default_max_budget; ++ ++ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0]; ++ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1]; ++ bfqd->bfq_back_max = bfq_back_max; ++ bfqd->bfq_back_penalty = bfq_back_penalty; ++ bfqd->bfq_slice_idle = bfq_slice_idle; ++ bfqd->bfq_timeout = bfq_timeout; ++ ++ bfqd->bfq_requests_within_timer = 120; ++ ++ bfqd->bfq_large_burst_thresh = 8; ++ bfqd->bfq_burst_interval = msecs_to_jiffies(180); ++ ++ bfqd->low_latency = true; ++ ++ /* ++ * Trade-off between responsiveness and fairness. ++ */ ++ bfqd->bfq_wr_coeff = 30; ++ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300); ++ bfqd->bfq_wr_max_time = 0; ++ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000); ++ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500); ++ bfqd->bfq_wr_max_softrt_rate = 7000; /* ++ * Approximate rate required ++ * to playback or record a ++ * high-definition compressed ++ * video. ++ */ ++ bfqd->wr_busy_queues = 0; ++ ++ /* ++ * Begin by assuming, optimistically, that the device peak ++ * rate is equal to 2/3 of the highest reference rate. ++ */ ++ bfqd->rate_dur_prod = ref_rate[blk_queue_nonrot(bfqd->queue)] * ++ ref_wr_duration[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->peak_rate = ref_rate[blk_queue_nonrot(bfqd->queue)] * 2 / 3; ++ ++ spin_lock_init(&bfqd->lock); ++ ++ /* ++ * The invocation of the next bfq_create_group_hierarchy ++ * function is the head of a chain of function calls ++ * (bfq_create_group_hierarchy->blkcg_activate_policy-> ++ * blk_mq_freeze_queue) that may lead to the invocation of the ++ * has_work hook function. For this reason, ++ * bfq_create_group_hierarchy is invoked only after all ++ * scheduler data has been initialized, apart from the fields ++ * that can be initialized only after invoking ++ * bfq_create_group_hierarchy. This, in particular, enables ++ * has_work to correctly return false. Of course, to avoid ++ * other inconsistencies, the blk-mq stack must then refrain ++ * from invoking further scheduler hooks before this init ++ * function is finished. ++ */ ++ bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node); ++ if (!bfqd->root_group) ++ goto out_free; ++ bfq_init_root_group(bfqd->root_group, bfqd); ++ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); ++ ++ wbt_disable_default(q); ++ return 0; ++ ++out_free: ++ kfree(bfqd); ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++} ++ ++static void bfq_slab_kill(void) ++{ ++ kmem_cache_destroy(bfq_pool); ++} ++ ++static int __init bfq_slab_setup(void) ++{ ++ bfq_pool = KMEM_CACHE(bfq_queue, 0); ++ if (!bfq_pool) ++ return -ENOMEM; ++ return 0; ++} ++ ++static ssize_t bfq_var_show(unsigned int var, char *page) ++{ ++ return sprintf(page, "%u\n", var); ++} ++ ++static ssize_t bfq_var_store(unsigned long *var, const char *page, ++ size_t count) ++{ ++ unsigned long new_val; ++ int ret = kstrtoul(page, 10, &new_val); ++ ++ if (ret == 0) ++ *var = new_val; ++ ++ return count; ++} ++ ++static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ ++ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ? ++ jiffies_to_msecs(bfqd->bfq_wr_max_time) : ++ jiffies_to_msecs(bfq_wr_duration(bfqd))); ++} ++ ++static ssize_t bfq_weights_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_queue *bfqq; ++ struct bfq_data *bfqd = e->elevator_data; ++ ssize_t num_char = 0; ++ ++ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n", ++ bfqd->queued); ++ ++ spin_lock_irq(&bfqd->lock); ++ ++ num_char += sprintf(page + num_char, "Active:\n"); ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, nr_queued %d %d, ", ++ bfqq->pid, ++ bfqq->entity.weight, ++ bfqq->queued[0], ++ bfqq->queued[1]); ++ num_char += sprintf(page + num_char, ++ "dur %d/%u\n", ++ jiffies_to_msecs( ++ jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ num_char += sprintf(page + num_char, "Idle:\n"); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ jiffies_to_msecs(jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ spin_unlock_irq(&bfqd->lock); ++ ++ return num_char; ++} ++ ++#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ u64 __data = __VAR; \ ++ if (__CONV == 1) \ ++ __data = jiffies_to_msecs(__data); \ ++ else if (__CONV == 2) \ ++ __data = div_u64(__data, NSEC_PER_MSEC); \ ++ return bfq_var_show(__data, (page)); \ ++} ++SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2); ++SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2); ++SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); ++SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); ++SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2); ++SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); ++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1); ++SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0); ++SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0); ++SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0); ++SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1); ++SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1); ++SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async, ++ 1); ++SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0); ++#undef SHOW_FUNCTION ++ ++#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ u64 __data = __VAR; \ ++ __data = div_u64(__data, NSEC_PER_USEC); \ ++ return bfq_var_show(__data, (page)); \ ++} ++USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle); ++#undef USEC_SHOW_FUNCTION ++ ++#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ ++static ssize_t \ ++__FUNC(struct elevator_queue *e, const char *page, size_t count) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ if (__CONV == 1) \ ++ *(__PTR) = msecs_to_jiffies(__data); \ ++ else if (__CONV == 2) \ ++ *(__PTR) = (u64)__data * NSEC_PER_MSEC; \ ++ else \ ++ *(__PTR) = __data; \ ++ return ret; \ ++} ++STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1, ++ INT_MAX, 2); ++STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1, ++ INT_MAX, 2); ++STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); ++STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, ++ INT_MAX, 0); ++STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2); ++STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX, ++ 1); ++STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_min_inter_arr_async_store, ++ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0, ++ INT_MAX, 0); ++#undef STORE_FUNCTION ++ ++#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ ++static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ *(__PTR) = (u64)__data * NSEC_PER_USEC; \ ++ return ret; \ ++} ++USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0, ++ UINT_MAX); ++#undef USEC_STORE_FUNCTION ++ ++/* do nothing for the moment */ ++static ssize_t bfq_weights_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ return count; ++} ++ ++static ssize_t bfq_max_budget_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data == 0) ++ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); ++ else { ++ if (__data > INT_MAX) ++ __data = INT_MAX; ++ bfqd->bfq_max_budget = __data; ++ } ++ ++ bfqd->bfq_user_max_budget = __data; ++ ++ return ret; ++} ++ ++/* ++ * Leaving this name to preserve name compatibility with cfq ++ * parameters, but this timeout is used for both sync and async. ++ */ ++static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data < 1) ++ __data = 1; ++ else if (__data > INT_MAX) ++ __data = INT_MAX; ++ ++ bfqd->bfq_timeout = msecs_to_jiffies(__data); ++ if (bfqd->bfq_user_max_budget == 0) ++ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); ++ ++ return ret; ++} ++ ++static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (!bfqd->strict_guarantees && __data == 1 ++ && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC) ++ bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC; ++ ++ bfqd->strict_guarantees = __data; ++ ++ return ret; ++} ++ ++static ssize_t bfq_low_latency_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (__data == 0 && bfqd->low_latency != 0) ++ bfq_end_wr(bfqd); ++ bfqd->low_latency = __data; ++ ++ return ret; ++} ++ ++#define BFQ_ATTR(name) \ ++ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store) ++ ++static struct elv_fs_entry bfq_attrs[] = { ++ BFQ_ATTR(fifo_expire_sync), ++ BFQ_ATTR(fifo_expire_async), ++ BFQ_ATTR(back_seek_max), ++ BFQ_ATTR(back_seek_penalty), ++ BFQ_ATTR(slice_idle), ++ BFQ_ATTR(slice_idle_us), ++ BFQ_ATTR(max_budget), ++ BFQ_ATTR(timeout_sync), ++ BFQ_ATTR(strict_guarantees), ++ BFQ_ATTR(low_latency), ++ BFQ_ATTR(wr_coeff), ++ BFQ_ATTR(wr_max_time), ++ BFQ_ATTR(wr_rt_max_time), ++ BFQ_ATTR(wr_min_idle_time), ++ BFQ_ATTR(wr_min_inter_arr_async), ++ BFQ_ATTR(wr_max_softrt_rate), ++ BFQ_ATTR(weights), ++ __ATTR_NULL ++}; ++ ++static struct elevator_type iosched_bfq_mq = { ++ .ops.mq = { ++ .limit_depth = bfq_limit_depth, ++ .prepare_request = bfq_prepare_request, ++ .requeue_request = bfq_finish_requeue_request, ++ .finish_request = bfq_finish_requeue_request, ++ .exit_icq = bfq_exit_icq, ++ .insert_requests = bfq_insert_requests, ++ .dispatch_request = bfq_dispatch_request, ++ .next_request = elv_rb_latter_request, ++ .former_request = elv_rb_former_request, ++ .allow_merge = bfq_allow_bio_merge, ++ .bio_merge = bfq_bio_merge, ++ .request_merge = bfq_request_merge, ++ .requests_merged = bfq_requests_merged, ++ .request_merged = bfq_request_merged, ++ .has_work = bfq_has_work, ++ .depth_updated = bfq_depth_updated, ++ .init_hctx = bfq_init_hctx, ++ .init_sched = bfq_init_queue, ++ .exit_sched = bfq_exit_queue, ++ }, ++ ++ .uses_mq = true, ++ .icq_size = sizeof(struct bfq_io_cq), ++ .icq_align = __alignof__(struct bfq_io_cq), ++ .elevator_attrs = bfq_attrs, ++ .elevator_name = "bfq-mq", ++ .elevator_owner = THIS_MODULE, ++}; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct blkcg_policy blkcg_policy_bfq = { ++ .dfl_cftypes = bfq_blkg_files, ++ .legacy_cftypes = bfq_blkcg_legacy_files, ++ ++ .cpd_alloc_fn = bfq_cpd_alloc, ++ .cpd_init_fn = bfq_cpd_init, ++ .cpd_bind_fn = bfq_cpd_init, ++ .cpd_free_fn = bfq_cpd_free, ++ ++ .pd_alloc_fn = bfq_pd_alloc, ++ .pd_init_fn = bfq_pd_init, ++ .pd_offline_fn = bfq_pd_offline, ++ .pd_free_fn = bfq_pd_free, ++ .pd_reset_stats_fn = bfq_pd_reset_stats, ++}; ++#endif ++ ++static int __init bfq_init(void) ++{ ++ int ret; ++ char msg[60] = "BFQ I/O-scheduler: v9"; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ ret = blkcg_policy_register(&blkcg_policy_bfq); ++ if (ret) ++ return ret; ++#endif ++ ++ ret = -ENOMEM; ++ if (bfq_slab_setup()) ++ goto err_pol_unreg; ++ ++ /* ++ * Times to load large popular applications for the typical ++ * systems installed on the reference devices (see the ++ * comments before the definition of the next ++ * array). Actually, we use slightly lower values, as the ++ * estimated peak rate tends to be smaller than the actual ++ * peak rate. The reason for this last fact is that estimates ++ * are computed over much shorter time intervals than the long ++ * intervals typically used for benchmarking. Why? First, to ++ * adapt more quickly to variations. Second, because an I/O ++ * scheduler cannot rely on a peak-rate-evaluation workload to ++ * be run for a long time. ++ */ ++ ref_wr_duration[0] = msecs_to_jiffies(7000); /* actually 8 sec */ ++ ref_wr_duration[1] = msecs_to_jiffies(2500); /* actually 3 sec */ ++ ++ ret = elv_register(&iosched_bfq_mq); ++ if (ret) ++ goto slab_kill; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ strcat(msg, " (with cgroups support)"); ++#endif ++ pr_info("%s", msg); ++ ++ return 0; ++ ++slab_kill: ++ bfq_slab_kill(); ++err_pol_unreg: ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ return ret; ++} ++ ++static void __exit bfq_exit(void) ++{ ++ elv_unregister(&iosched_bfq_mq); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ bfq_slab_kill(); ++} ++ ++module_init(bfq_init); ++module_exit(bfq_exit); ++ ++MODULE_AUTHOR("Paolo Valente"); ++MODULE_LICENSE("GPL"); ++MODULE_DESCRIPTION("MQ Budget Fair Queueing I/O Scheduler"); +diff --git a/block/bfq-mq.h b/block/bfq-mq.h +new file mode 100644 +index 000000000000..ceb291132a1a +--- /dev/null ++++ b/block/bfq-mq.h +@@ -0,0 +1,1077 @@ ++/* ++ * BFQ v9: data structures and common functions prototypes. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org> ++ */ ++ ++#ifndef _BFQ_H ++#define _BFQ_H ++ ++#include <linux/hrtimer.h> ++#include <linux/blk-cgroup.h> ++ ++/* see comments on CONFIG_BFQ_GROUP_IOSCHED in bfq.h */ ++#ifdef CONFIG_MQ_BFQ_GROUP_IOSCHED ++#define BFQ_GROUP_IOSCHED_ENABLED ++#endif ++ ++#define BFQ_IOPRIO_CLASSES 3 ++#define BFQ_CL_IDLE_TIMEOUT (HZ/5) ++ ++#define BFQ_MIN_WEIGHT 1 ++#define BFQ_MAX_WEIGHT 1000 ++#define BFQ_WEIGHT_CONVERSION_COEFF 10 ++ ++#define BFQ_DEFAULT_QUEUE_IOPRIO 4 ++ ++#define BFQ_WEIGHT_LEGACY_DFL 100 ++#define BFQ_DEFAULT_GRP_IOPRIO 0 ++#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE ++ ++/* ++ * Soft real-time applications are extremely more latency sensitive ++ * than interactive ones. Over-raise the weight of the former to ++ * privilege them against the latter. ++ */ ++#define BFQ_SOFTRT_WEIGHT_FACTOR 100 ++ ++struct bfq_entity; ++ ++/** ++ * struct bfq_service_tree - per ioprio_class service tree. ++ * ++ * Each service tree represents a B-WF2Q+ scheduler on its own. Each ++ * ioprio_class has its own independent scheduler, and so its own ++ * bfq_service_tree. All the fields are protected by the queue lock ++ * of the containing bfqd. ++ */ ++struct bfq_service_tree { ++ /* tree for active entities (i.e., those backlogged) */ ++ struct rb_root active; ++ /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ ++ struct rb_root idle; ++ ++ struct bfq_entity *first_idle; /* idle entity with minimum F_i */ ++ struct bfq_entity *last_idle; /* idle entity with maximum F_i */ ++ ++ u64 vtime; /* scheduler virtual time */ ++ /* scheduler weight sum; active and idle entities contribute to it */ ++ unsigned long wsum; ++}; ++ ++/** ++ * struct bfq_sched_data - multi-class scheduler. ++ * ++ * bfq_sched_data is the basic scheduler queue. It supports three ++ * ioprio_classes, and can be used either as a toplevel queue or as an ++ * intermediate queue in a hierarchical setup. ++ * ++ * The supported ioprio_classes are the same as in CFQ, in descending ++ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. ++ * Requests from higher priority queues are served before all the ++ * requests from lower priority queues; among requests of the same ++ * queue requests are served according to B-WF2Q+. ++ * ++ * The schedule is implemented by the service trees, plus the field ++ * @next_in_service, which points to the entity on the active trees ++ * that will be served next, if 1) no changes in the schedule occurs ++ * before the current in-service entity is expired, 2) the in-service ++ * queue becomes idle when it expires, and 3) if the entity pointed by ++ * in_service_entity is not a queue, then the in-service child entity ++ * of the entity pointed by in_service_entity becomes idle on ++ * expiration. This peculiar definition allows for the following ++ * optimization, not yet exploited: while a given entity is still in ++ * service, we already know which is the best candidate for next ++ * service among the other active entitities in the same parent ++ * entity. We can then quickly compare the timestamps of the ++ * in-service entity with those of such best candidate. ++ * ++ * All the fields are protected by the queue lock of the containing ++ * bfqd. ++ */ ++struct bfq_sched_data { ++ struct bfq_entity *in_service_entity; /* entity in service */ ++ /* head-of-the-line entity in the scheduler (see comments above) */ ++ struct bfq_entity *next_in_service; ++ /* array of service trees, one per ioprio_class */ ++ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; ++ /* last time CLASS_IDLE was served */ ++ unsigned long bfq_class_idle_last_service; ++ ++}; ++ ++/** ++ * struct bfq_weight_counter - counter of the number of all active queues ++ * with a given weight. ++ */ ++struct bfq_weight_counter { ++ unsigned int weight; /* weight of the queues this counter refers to */ ++ unsigned int num_active; /* nr of active queues with this weight */ ++ /* ++ * Weights tree member (see bfq_data's @queue_weights_tree) ++ */ ++ struct rb_node weights_node; ++}; ++ ++/** ++ * struct bfq_entity - schedulable entity. ++ * ++ * A bfq_entity is used to represent either a bfq_queue (leaf node in the ++ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each ++ * entity belongs to the sched_data of the parent group in the cgroup ++ * hierarchy. Non-leaf entities have also their own sched_data, stored ++ * in @my_sched_data. ++ * ++ * Each entity stores independently its priority values; this would ++ * allow different weights on different devices, but this ++ * functionality is not exported to userspace by now. Priorities and ++ * weights are updated lazily, first storing the new values into the ++ * new_* fields, then setting the @prio_changed flag. As soon as ++ * there is a transition in the entity state that allows the priority ++ * update to take place the effective and the requested priority ++ * values are synchronized. ++ * ++ * Unless cgroups are used, the weight value is calculated from the ++ * ioprio to export the same interface as CFQ. When dealing with ++ * ``well-behaved'' queues (i.e., queues that do not spend too much ++ * time to consume their budget and have true sequential behavior, and ++ * when there are no external factors breaking anticipation) the ++ * relative weights at each level of the cgroups hierarchy should be ++ * guaranteed. All the fields are protected by the queue lock of the ++ * containing bfqd. ++ */ ++struct bfq_entity { ++ struct rb_node rb_node; /* service_tree member */ ++ ++ /* ++ * Flag, true if the entity is on a tree (either the active or ++ * the idle one of its service_tree) or is in service. ++ */ ++ bool on_st; ++ ++ u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */ ++ u64 start; /* B-WF2Q+ start timestamp (aka S_i) */ ++ ++ /* tree the entity is enqueued into; %NULL if not on a tree */ ++ struct rb_root *tree; ++ ++ /* ++ * minimum start time of the (active) subtree rooted at this ++ * entity; used for O(log N) lookups into active trees ++ */ ++ u64 min_start; ++ ++ /* amount of service received during the last service slot */ ++ int service; ++ ++ /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ ++ int budget; ++ ++ unsigned int weight; /* weight of the queue */ ++ unsigned int new_weight; /* next weight if a change is in progress */ ++ ++ /* original weight, used to implement weight boosting */ ++ unsigned int orig_weight; ++ ++ /* parent entity, for hierarchical scheduling */ ++ struct bfq_entity *parent; ++ ++ /* ++ * For non-leaf nodes in the hierarchy, the associated ++ * scheduler queue, %NULL on leaf nodes. ++ */ ++ struct bfq_sched_data *my_sched_data; ++ /* the scheduler queue this entity belongs to */ ++ struct bfq_sched_data *sched_data; ++ ++ /* flag, set to request a weight, ioprio or ioprio_class change */ ++ int prio_changed; ++ ++ /* flag, set if the entity is counted in groups_with_pending_reqs */ ++ bool in_groups_with_pending_reqs; ++}; ++ ++struct bfq_group; ++ ++/** ++ * struct bfq_ttime - per process thinktime stats. ++ */ ++struct bfq_ttime { ++ u64 last_end_request; /* completion time of last request */ ++ ++ u64 ttime_total; /* total process thinktime */ ++ unsigned long ttime_samples; /* number of thinktime samples */ ++ u64 ttime_mean; /* average process thinktime */ ++ ++}; ++ ++/** ++ * struct bfq_queue - leaf schedulable entity. ++ * ++ * A bfq_queue is a leaf request queue; it can be associated with an ++ * io_context or more, if it is async or shared between cooperating ++ * processes. @cgroup holds a reference to the cgroup, to be sure that it ++ * does not disappear while a bfqq still references it (mostly to avoid ++ * races between request issuing and task migration followed by cgroup ++ * destruction). ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_queue { ++ /* reference counter */ ++ int ref; ++ /* parent bfq_data */ ++ struct bfq_data *bfqd; ++ ++ /* current ioprio and ioprio class */ ++ unsigned short ioprio, ioprio_class; ++ /* next ioprio and ioprio class if a change is in progress */ ++ unsigned short new_ioprio, new_ioprio_class; ++ ++ /* ++ * Shared bfq_queue if queue is cooperating with one or more ++ * other queues. ++ */ ++ struct bfq_queue *new_bfqq; ++ /* request-position tree member (see bfq_group's @rq_pos_tree) */ ++ struct rb_node pos_node; ++ /* request-position tree root (see bfq_group's @rq_pos_tree) */ ++ struct rb_root *pos_root; ++ ++ /* sorted list of pending requests */ ++ struct rb_root sort_list; ++ /* if fifo isn't expired, next request to serve */ ++ struct request *next_rq; ++ /* number of sync and async requests queued */ ++ int queued[2]; ++ /* number of requests currently allocated */ ++ int allocated; ++ /* number of pending metadata requests */ ++ int meta_pending; ++ /* fifo list of requests in sort_list */ ++ struct list_head fifo; ++ ++ /* entity representing this queue in the scheduler */ ++ struct bfq_entity entity; ++ ++ /* pointer to the weight counter associated with this queue */ ++ struct bfq_weight_counter *weight_counter; ++ ++ /* maximum budget allowed from the feedback mechanism */ ++ int max_budget; ++ /* budget expiration (in jiffies) */ ++ unsigned long budget_timeout; ++ ++ /* number of requests on the dispatch list or inside driver */ ++ int dispatched; ++ ++ unsigned int flags; /* status flags.*/ ++ ++ /* node for active/idle bfqq list inside parent bfqd */ ++ struct list_head bfqq_list; ++ ++ /* associated @bfq_ttime struct */ ++ struct bfq_ttime ttime; ++ ++ /* bit vector: a 1 for each seeky requests in history */ ++ u32 seek_history; ++ ++ /* node for the device's burst list */ ++ struct hlist_node burst_list_node; ++ ++ /* position of the last request enqueued */ ++ sector_t last_request_pos; ++ ++ /* Number of consecutive pairs of request completion and ++ * arrival, such that the queue becomes idle after the ++ * completion, but the next request arrives within an idle ++ * time slice; used only if the queue's IO_bound flag has been ++ * cleared. ++ */ ++ unsigned int requests_within_timer; ++ ++ /* pid of the process owning the queue, used for logging purposes */ ++ pid_t pid; ++ ++ /* ++ * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL ++ * if the queue is shared. ++ */ ++ struct bfq_io_cq *bic; ++ ++ /* current maximum weight-raising time for this queue */ ++ unsigned long wr_cur_max_time; ++ /* ++ * Minimum time instant such that, only if a new request is ++ * enqueued after this time instant in an idle @bfq_queue with ++ * no outstanding requests, then the task associated with the ++ * queue it is deemed as soft real-time (see the comments on ++ * the function bfq_bfqq_softrt_next_start()) ++ */ ++ unsigned long soft_rt_next_start; ++ /* ++ * Start time of the current weight-raising period if ++ * the @bfq-queue is being weight-raised, otherwise ++ * finish time of the last weight-raising period. ++ */ ++ unsigned long last_wr_start_finish; ++ /* factor by which the weight of this queue is multiplied */ ++ unsigned int wr_coeff; ++ /* ++ * Time of the last transition of the @bfq_queue from idle to ++ * backlogged. ++ */ ++ unsigned long last_idle_bklogged; ++ /* ++ * Cumulative service received from the @bfq_queue since the ++ * last transition from idle to backlogged. ++ */ ++ unsigned long service_from_backlogged; ++ /* ++ * Cumulative service received from the @bfq_queue since its ++ * last transition to weight-raised state. ++ */ ++ unsigned long service_from_wr; ++ /* ++ * Value of wr start time when switching to soft rt ++ */ ++ unsigned long wr_start_at_switch_to_srt; ++ ++ unsigned long split_time; /* time of last split */ ++ unsigned long first_IO_time; /* time of first I/O for this queue */ ++ ++ /* max service rate measured so far */ ++ u32 max_service_rate; ++ /* ++ * Ratio between the service received by bfqq while it is in ++ * service, and the cumulative service (of requests of other ++ * queues) that may be injected while bfqq is empty but still ++ * in service. To increase precision, the coefficient is ++ * measured in tenths of unit. Here are some example of (1) ++ * ratios, (2) resulting percentages of service injected ++ * w.r.t. to the total service dispatched while bfqq is in ++ * service, and (3) corresponding values of the coefficient: ++ * 1 (50%) -> 10 ++ * 2 (33%) -> 20 ++ * 10 (9%) -> 100 ++ * 9.9 (9%) -> 99 ++ * 1.5 (40%) -> 15 ++ * 0.5 (66%) -> 5 ++ * 0.1 (90%) -> 1 ++ * ++ * So, if the coefficient is lower than 10, then ++ * injected service is more than bfqq service. ++ */ ++ unsigned int inject_coeff; ++ /* amount of service injected in current service slot */ ++ unsigned int injected_service; ++}; ++ ++/** ++ * struct bfq_io_cq - per (request_queue, io_context) structure. ++ */ ++struct bfq_io_cq { ++ /* associated io_cq structure */ ++ struct io_cq icq; /* must be the first member */ ++ /* array of two process queues, the sync and the async */ ++ struct bfq_queue *bfqq[2]; ++ /* per (request_queue, blkcg) ioprio */ ++ int ioprio; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ uint64_t blkcg_serial_nr; /* the current blkcg serial */ ++#endif ++ ++ /* ++ * Snapshot of the has_short_time flag before merging; taken ++ * to remember its value while the queue is merged, so as to ++ * be able to restore it in case of split. ++ */ ++ bool saved_has_short_ttime; ++ /* ++ * Same purpose as the previous two fields for the I/O bound ++ * classification of a queue. ++ */ ++ bool saved_IO_bound; ++ ++ /* ++ * Same purpose as the previous fields for the value of the ++ * field keeping the queue's belonging to a large burst ++ */ ++ bool saved_in_large_burst; ++ /* ++ * True if the queue belonged to a burst list before its merge ++ * with another cooperating queue. ++ */ ++ bool was_in_burst_list; ++ ++ /* ++ * Similar to previous fields: save wr information. ++ */ ++ unsigned long saved_wr_coeff; ++ unsigned long saved_last_wr_start_finish; ++ unsigned long saved_wr_start_at_switch_to_srt; ++ unsigned int saved_wr_cur_max_time; ++ struct bfq_ttime saved_ttime; ++}; ++ ++/** ++ * struct bfq_data - per-device data structure. ++ * ++ * All the fields are protected by @lock. ++ */ ++struct bfq_data { ++ /* device request queue */ ++ struct request_queue *queue; ++ /* dispatch queue */ ++ struct list_head dispatch; ++ ++ /* root bfq_group for the device */ ++ struct bfq_group *root_group; ++ ++ /* ++ * rbtree of weight counters of @bfq_queues, sorted by ++ * weight. Used to keep track of whether all @bfq_queues have ++ * the same weight. The tree contains one counter for each ++ * distinct weight associated to some active and not ++ * weight-raised @bfq_queue (see the comments to the functions ++ * bfq_weights_tree_[add|remove] for further details). ++ */ ++ struct rb_root queue_weights_tree; ++ ++ /* ++ * Number of groups with at least one descendant process that ++ * has at least one request waiting for completion. Note that ++ * this accounts for also requests already dispatched, but not ++ * yet completed. Therefore this number of groups may differ ++ * (be larger) than the number of active groups, as a group is ++ * considered active only if its corresponding entity has ++ * descendant queues with at least one request queued. This ++ * number is used to decide whether a scenario is symmetric. ++ * For a detailed explanation see comments on the computation ++ * of the variable asymmetric_scenario in the function ++ * bfq_better_to_idle(). ++ * ++ * However, it is hard to compute this number exactly, for ++ * groups with multiple descendant processes. Consider a group ++ * that is inactive, i.e., that has no descendant process with ++ * pending I/O inside BFQ queues. Then suppose that ++ * num_groups_with_pending_reqs is still accounting for this ++ * group, because the group has descendant processes with some ++ * I/O request still in flight. num_groups_with_pending_reqs ++ * should be decremented when the in-flight request of the ++ * last descendant process is finally completed (assuming that ++ * nothing else has changed for the group in the meantime, in ++ * terms of composition of the group and active/inactive state of child ++ * groups and processes). To accomplish this, an additional ++ * pending-request counter must be added to entities, and must ++ * be updated correctly. To avoid this additional field and operations, ++ * we resort to the following tradeoff between simplicity and ++ * accuracy: for an inactive group that is still counted in ++ * num_groups_with_pending_reqs, we decrement ++ * num_groups_with_pending_reqs when the first descendant ++ * process of the group remains with no request waiting for ++ * completion. ++ * ++ * Even this simpler decrement strategy requires a little ++ * carefulness: to avoid multiple decrements, we flag a group, ++ * more precisely an entity representing a group, as still ++ * counted in num_groups_with_pending_reqs when it becomes ++ * inactive. Then, when the first descendant queue of the ++ * entity remains with no request waiting for completion, ++ * num_groups_with_pending_reqs is decremented, and this flag ++ * is reset. After this flag is reset for the entity, ++ * num_groups_with_pending_reqs won't be decremented any ++ * longer in case a new descendant queue of the entity remains ++ * with no request waiting for completion. ++ */ ++ unsigned int num_groups_with_pending_reqs; ++ ++ /* ++ * Per-class (RT, BE, IDLE) number of bfq_queues containing ++ * requests (including the queue in service, even if it is ++ * idling). ++ */ ++ unsigned int busy_queues[3]; ++ /* number of weight-raised busy @bfq_queues */ ++ int wr_busy_queues; ++ /* number of queued requests */ ++ int queued; ++ /* number of requests dispatched and waiting for completion */ ++ int rq_in_driver; ++ ++ /* ++ * Maximum number of requests in driver in the last ++ * @hw_tag_samples completed requests. ++ */ ++ int max_rq_in_driver; ++ /* number of samples used to calculate hw_tag */ ++ int hw_tag_samples; ++ /* flag set to one if the driver is showing a queueing behavior */ ++ int hw_tag; ++ ++ /* number of budgets assigned */ ++ int budgets_assigned; ++ ++ /* ++ * Timer set when idling (waiting) for the next request from ++ * the queue in service. ++ */ ++ struct hrtimer idle_slice_timer; ++ ++ /* bfq_queue in service */ ++ struct bfq_queue *in_service_queue; ++ ++ /* on-disk position of the last served request */ ++ sector_t last_position; ++ ++ /* position of the last served request for the in-service queue */ ++ sector_t in_serv_last_pos; ++ ++ /* time of last request completion (ns) */ ++ u64 last_completion; ++ ++ /* time of first rq dispatch in current observation interval (ns) */ ++ u64 first_dispatch; ++ /* time of last rq dispatch in current observation interval (ns) */ ++ u64 last_dispatch; ++ ++ /* beginning of the last budget */ ++ ktime_t last_budget_start; ++ /* beginning of the last idle slice */ ++ ktime_t last_idling_start; ++ ++ /* number of samples in current observation interval */ ++ int peak_rate_samples; ++ /* num of samples of seq dispatches in current observation interval */ ++ u32 sequential_samples; ++ /* total num of sectors transferred in current observation interval */ ++ u64 tot_sectors_dispatched; ++ /* max rq size seen during current observation interval (sectors) */ ++ u32 last_rq_max_size; ++ /* time elapsed from first dispatch in current observ. interval (us) */ ++ u64 delta_from_first; ++ /* ++ * Current estimate of the device peak rate, measured in ++ * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by ++ * BFQ_RATE_SHIFT is performed to increase precision in ++ * fixed-point calculations. ++ */ ++ u32 peak_rate; ++ ++ /* maximum budget allotted to a bfq_queue before rescheduling */ ++ int bfq_max_budget; ++ ++ /* list of all the bfq_queues active on the device */ ++ struct list_head active_list; ++ /* list of all the bfq_queues idle on the device */ ++ struct list_head idle_list; ++ ++ /* ++ * Timeout for async/sync requests; when it fires, requests ++ * are served in fifo order. ++ */ ++ u64 bfq_fifo_expire[2]; ++ /* weight of backward seeks wrt forward ones */ ++ unsigned int bfq_back_penalty; ++ /* maximum allowed backward seek */ ++ unsigned int bfq_back_max; ++ /* maximum idling time */ ++ u32 bfq_slice_idle; ++ ++ /* user-configured max budget value (0 for auto-tuning) */ ++ int bfq_user_max_budget; ++ /* ++ * Timeout for bfq_queues to consume their budget; used to ++ * prevent seeky queues from imposing long latencies to ++ * sequential or quasi-sequential ones (this also implies that ++ * seeky queues cannot receive guarantees in the service ++ * domain; after a timeout they are charged for the time they ++ * have been in service, to preserve fairness among them, but ++ * without service-domain guarantees). ++ */ ++ unsigned int bfq_timeout; ++ ++ /* ++ * Number of consecutive requests that must be issued within ++ * the idle time slice to set again idling to a queue which ++ * was marked as non-I/O-bound (see the definition of the ++ * IO_bound flag for further details). ++ */ ++ unsigned int bfq_requests_within_timer; ++ ++ /* ++ * Force device idling whenever needed to provide accurate ++ * service guarantees, without caring about throughput ++ * issues. CAVEAT: this may even increase latencies, in case ++ * of useless idling for processes that did stop doing I/O. ++ */ ++ bool strict_guarantees; ++ ++ /* ++ * Last time at which a queue entered the current burst of ++ * queues being activated shortly after each other; for more ++ * details about this and the following parameters related to ++ * a burst of activations, see the comments on the function ++ * bfq_handle_burst. ++ */ ++ unsigned long last_ins_in_burst; ++ /* ++ * Reference time interval used to decide whether a queue has ++ * been activated shortly after @last_ins_in_burst. ++ */ ++ unsigned long bfq_burst_interval; ++ /* number of queues in the current burst of queue activations */ ++ int burst_size; ++ ++ /* common parent entity for the queues in the burst */ ++ struct bfq_entity *burst_parent_entity; ++ /* Maximum burst size above which the current queue-activation ++ * burst is deemed as 'large'. ++ */ ++ unsigned long bfq_large_burst_thresh; ++ /* true if a large queue-activation burst is in progress */ ++ bool large_burst; ++ /* ++ * Head of the burst list (as for the above fields, more ++ * details in the comments on the function bfq_handle_burst). ++ */ ++ struct hlist_head burst_list; ++ ++ /* if set to true, low-latency heuristics are enabled */ ++ bool low_latency; ++ /* ++ * Maximum factor by which the weight of a weight-raised queue ++ * is multiplied. ++ */ ++ unsigned int bfq_wr_coeff; ++ /* maximum duration of a weight-raising period (jiffies) */ ++ unsigned int bfq_wr_max_time; ++ ++ /* Maximum weight-raising duration for soft real-time processes */ ++ unsigned int bfq_wr_rt_max_time; ++ /* ++ * Minimum idle period after which weight-raising may be ++ * reactivated for a queue (in jiffies). ++ */ ++ unsigned int bfq_wr_min_idle_time; ++ /* ++ * Minimum period between request arrivals after which ++ * weight-raising may be reactivated for an already busy async ++ * queue (in jiffies). ++ */ ++ unsigned long bfq_wr_min_inter_arr_async; ++ ++ /* Max service-rate for a soft real-time queue, in sectors/sec */ ++ unsigned int bfq_wr_max_softrt_rate; ++ /* ++ * Cached value of the product ref_rate*ref_wr_duration, used ++ * for computing the maximum duration of weight raising ++ * automatically. ++ */ ++ u64 rate_dur_prod; ++ ++ /* fallback dummy bfqq for extreme OOM conditions */ ++ struct bfq_queue oom_bfqq; ++ ++ spinlock_t lock; ++ ++ /* ++ * bic associated with the task issuing current bio for ++ * merging. This and the next field are used as a support to ++ * be able to perform the bic lookup, needed by bio-merge ++ * functions, before the scheduler lock is taken, and thus ++ * avoid taking the request-queue lock while the scheduler ++ * lock is being held. ++ */ ++ struct bfq_io_cq *bio_bic; ++ /* bfqq associated with the task issuing current bio for merging */ ++ struct bfq_queue *bio_bfqq; ++ /* Extra flag used only for TESTING */ ++ bool bio_bfqq_set; ++ ++ /* ++ * Depth limits used in bfq_limit_depth (see comments on the ++ * function) ++ */ ++ unsigned int word_depths[2][2]; ++}; ++ ++enum bfqq_state_flags { ++ BFQ_BFQQ_FLAG_just_created = 0, /* queue just allocated */ ++ BFQ_BFQQ_FLAG_busy, /* has requests or is in service */ ++ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ ++ BFQ_BFQQ_FLAG_non_blocking_wait_rq, /* ++ * waiting for a request ++ * without idling the device ++ */ ++ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ ++ BFQ_BFQQ_FLAG_has_short_ttime, /* queue has a short think time */ ++ BFQ_BFQQ_FLAG_sync, /* synchronous queue */ ++ BFQ_BFQQ_FLAG_IO_bound, /* ++ * bfqq has timed-out at least once ++ * having consumed at most 2/10 of ++ * its budget ++ */ ++ BFQ_BFQQ_FLAG_in_large_burst, /* ++ * bfqq activated in a large burst, ++ * see comments to bfq_handle_burst. ++ */ ++ BFQ_BFQQ_FLAG_softrt_update, /* ++ * may need softrt-next-start ++ * update ++ */ ++ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ ++ BFQ_BFQQ_FLAG_split_coop /* shared bfqq will be split */ ++}; ++ ++#define BFQ_BFQQ_FNS(name) \ ++static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ ++{ \ ++ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ ++} ++ ++BFQ_BFQQ_FNS(just_created); ++BFQ_BFQQ_FNS(busy); ++BFQ_BFQQ_FNS(wait_request); ++BFQ_BFQQ_FNS(non_blocking_wait_rq); ++BFQ_BFQQ_FNS(fifo_expire); ++BFQ_BFQQ_FNS(has_short_ttime); ++BFQ_BFQQ_FNS(sync); ++BFQ_BFQQ_FNS(IO_bound); ++BFQ_BFQQ_FNS(in_large_burst); ++BFQ_BFQQ_FNS(coop); ++BFQ_BFQQ_FNS(split_coop); ++BFQ_BFQQ_FNS(softrt_update); ++#undef BFQ_BFQQ_FNS ++ ++/* Logging facilities. */ ++#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE ++ ++static const char *checked_dev_name(const struct device *dev) ++{ ++ static const char nodev[] = "nodev"; ++ ++ if (dev) ++ return dev_name(dev); ++ ++ return nodev; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ ++ pr_crit("%s bfq%d%c %s [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ bfqq_group(bfqq)->blkg_path, __func__, ##args); \ ++} while (0) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ ++ pr_crit("%s %s [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ bfqg->blkg_path, __func__, ##args); \ ++} while (0) ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ pr_crit("%s bfq%d%c [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ (bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __func__, ##args) ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ pr_crit("%s bfq [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ __func__, ##args) ++ ++#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */ ++ ++#if !defined(CONFIG_BLK_DEV_IO_TRACE) ++ ++/* Avoid possible "unused-variable" warning. See commit message. */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) ((void) (bfqq)) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) ((void) (bfqg)) ++ ++#define bfq_log(bfqd, fmt, args...) do {} while (0) ++ ++#else /* CONFIG_BLK_DEV_IO_TRACE */ ++ ++#include <linux/blktrace_api.h> ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \ ++ (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ bfqq_group(bfqq)->blkg_path, __func__, ##args); \ ++} while (0) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ ++ blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, bfqg->blkg_path, \ ++ __func__, ##args);\ ++} while (0) ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __func__, ##args) ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args) ++ ++#endif /* CONFIG_BLK_DEV_IO_TRACE */ ++#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */ ++ ++/* Expiration reasons. */ ++enum bfqq_expiration { ++ BFQ_BFQQ_TOO_IDLE = 0, /* ++ * queue has been idling for ++ * too long ++ */ ++ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ ++ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ ++ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ ++ BFQ_BFQQ_PREEMPTED /* preemption in progress */ ++}; ++ ++ ++struct bfqg_stats { ++#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP) ++ /* number of ios merged */ ++ struct blkg_rwstat merged; ++ /* total time spent on device in ns, may not be accurate w/ queueing */ ++ struct blkg_rwstat service_time; ++ /* total time spent waiting in scheduler queue in ns */ ++ struct blkg_rwstat wait_time; ++ /* number of IOs queued up */ ++ struct blkg_rwstat queued; ++ /* total disk time and nr sectors dispatched by this group */ ++ struct blkg_stat time; ++ /* sum of number of ios queued across all samples */ ++ struct blkg_stat avg_queue_size_sum; ++ /* count of samples taken for average */ ++ struct blkg_stat avg_queue_size_samples; ++ /* how many times this group has been removed from service tree */ ++ struct blkg_stat dequeue; ++ /* total time spent waiting for it to be assigned a timeslice. */ ++ struct blkg_stat group_wait_time; ++ /* time spent idling for this blkcg_gq */ ++ struct blkg_stat idle_time; ++ /* total time with empty current active q with other requests queued */ ++ struct blkg_stat empty_time; ++ /* fields after this shouldn't be cleared on stat reset */ ++ u64 start_group_wait_time; ++ u64 start_idle_time; ++ u64 start_empty_time; ++ uint16_t flags; ++#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */ ++}; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++/* ++ * struct bfq_group_data - per-blkcg storage for the blkio subsystem. ++ * ++ * @ps: @blkcg_policy_storage that this structure inherits ++ * @weight: weight of the bfq_group ++ */ ++struct bfq_group_data { ++ /* must be the first member */ ++ struct blkcg_policy_data pd; ++ ++ unsigned int weight; ++}; ++ ++/** ++ * struct bfq_group - per (device, cgroup) data structure. ++ * @entity: schedulable entity to insert into the parent group sched_data. ++ * @sched_data: own sched_data, to contain child entities (they may be ++ * both bfq_queues and bfq_groups). ++ * @bfqd: the bfq_data for the device this group acts upon. ++ * @async_bfqq: array of async queues for all the tasks belonging to ++ * the group, one queue per ioprio value per ioprio_class, ++ * except for the idle class that has only one queue. ++ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). ++ * @my_entity: pointer to @entity, %NULL for the toplevel group; used ++ * to avoid too many special cases during group creation/ ++ * migration. ++ * @active_entities: number of active entities belonging to the group; ++ * unused for the root group. Used to know whether there ++ * are groups with more than one active @bfq_entity ++ * (see the comments to the function ++ * bfq_bfqq_may_idle()). ++ * @rq_pos_tree: rbtree sorted by next_request position, used when ++ * determining if two or more queues have interleaving ++ * requests (see bfq_find_close_cooperator()). ++ * ++ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup ++ * there is a set of bfq_groups, each one collecting the lower-level ++ * entities belonging to the group that are acting on the same device. ++ * ++ * Locking works as follows: ++ * o @bfqd is protected by the queue lock, RCU is used to access it ++ * from the readers. ++ * o All the other fields are protected by the @bfqd queue lock. ++ */ ++struct bfq_group { ++ /* must be the first member */ ++ struct blkg_policy_data pd; ++ ++ /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */ ++ char blkg_path[128]; ++ ++ /* reference counter (see comments in bfq_bic_update_cgroup) */ ++ int ref; ++ ++ struct bfq_entity entity; ++ struct bfq_sched_data sched_data; ++ ++ void *bfqd; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct bfq_entity *my_entity; ++ ++ int active_entities; ++ ++ struct rb_root rq_pos_tree; ++ ++ struct bfqg_stats stats; ++}; ++ ++#else ++struct bfq_group { ++ struct bfq_sched_data sched_data; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct rb_root rq_pos_tree; ++}; ++#endif ++ ++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); ++ ++static unsigned int bfq_class_idx(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ return bfqq ? bfqq->ioprio_class - 1 : ++ BFQ_DEFAULT_GRP_CLASS - 1; ++} ++ ++static unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd) ++{ ++ return bfqd->busy_queues[0] + bfqd->busy_queues[1] + ++ bfqd->busy_queues[2]; ++} ++ ++static struct bfq_service_tree * ++bfq_entity_service_tree(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sched_data = entity->sched_data; ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned int idx = bfq_class_idx(entity); ++ ++ BUG_ON(idx >= BFQ_IOPRIO_CLASSES); ++ BUG_ON(sched_data == NULL); ++ ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "%p %d", ++ sched_data->service_tree + idx, idx); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "%p %d", ++ sched_data->service_tree + idx, idx); ++ } ++#endif ++ return sched_data->service_tree + idx; ++} ++ ++static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) ++{ ++ return bic->bfqq[is_sync]; ++} ++ ++static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, ++ bool is_sync) ++{ ++ bic->bfqq[is_sync] = bfqq; ++} ++ ++static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) ++{ ++ return bic->icq.q->elevator->elevator_data; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *group_entity = bfqq->entity.parent; ++ ++ if (!group_entity) ++ group_entity = &bfqq->bfqd->root_group->entity; ++ ++ return container_of(group_entity, struct bfq_group, entity); ++} ++ ++#else ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ return bfqq->bfqd->root_group; ++} ++ ++#endif ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); ++static void bfq_put_queue(struct bfq_queue *bfqq); ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic); ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); ++#endif ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++ ++#endif /* _BFQ_H */ +diff --git a/block/bfq-sched.c b/block/bfq-sched.c +new file mode 100644 +index 000000000000..7a4923231106 +--- /dev/null ++++ b/block/bfq-sched.c +@@ -0,0 +1,2077 @@ ++/* ++ * BFQ: Hierarchical B-WF2Q+ scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org> ++ */ ++ ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++ ++/** ++ * bfq_gt - compare two timestamps. ++ * @a: first ts. ++ * @b: second ts. ++ * ++ * Return @a > @b, dealing with wrapping correctly. ++ */ ++static int bfq_gt(u64 a, u64 b) ++{ ++ return (s64)(a - b) > 0; ++} ++ ++static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree) ++{ ++ struct rb_node *node = tree->rb_node; ++ ++ return rb_entry(node, struct bfq_entity, rb_node); ++} ++ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ bool expiration); ++ ++static bool bfq_update_parent_budget(struct bfq_entity *next_in_service); ++ ++/** ++ * bfq_update_next_in_service - update sd->next_in_service ++ * @sd: sched_data for which to perform the update. ++ * @new_entity: if not NULL, pointer to the entity whose activation, ++ * requeueing or repositionig triggered the invocation of ++ * this function. ++ * @expiration: id true, this function is being invoked after the ++ * expiration of the in-service entity ++ * ++ * This function is called to update sd->next_in_service, which, in ++ * its turn, may change as a consequence of the insertion or ++ * extraction of an entity into/from one of the active trees of ++ * sd. These insertions/extractions occur as a consequence of ++ * activations/deactivations of entities, with some activations being ++ * 'true' activations, and other activations being requeueings (i.e., ++ * implementing the second, requeueing phase of the mechanism used to ++ * reposition an entity in its active tree; see comments on ++ * __bfq_activate_entity and __bfq_requeue_entity for details). In ++ * both the last two activation sub-cases, new_entity points to the ++ * just activated or requeued entity. ++ * ++ * Returns true if sd->next_in_service changes in such a way that ++ * entity->parent may become the next_in_service for its parent ++ * entity. ++ */ ++static bool bfq_update_next_in_service(struct bfq_sched_data *sd, ++ struct bfq_entity *new_entity, ++ bool expiration) ++{ ++ struct bfq_entity *next_in_service = sd->next_in_service; ++ struct bfq_queue *bfqq; ++ bool parent_sched_may_change = false; ++ bool change_without_lookup = false; ++ ++ /* ++ * If this update is triggered by the activation, requeueing ++ * or repositiong of an entity that does not coincide with ++ * sd->next_in_service, then a full lookup in the active tree ++ * can be avoided. In fact, it is enough to check whether the ++ * just-modified entity has the same priority as ++ * sd->next_in_service, is eligible and has a lower virtual ++ * finish time than sd->next_in_service. If this compound ++ * condition holds, then the new entity becomes the new ++ * next_in_service. Otherwise no change is needed. ++ */ ++ if (new_entity && new_entity != sd->next_in_service) { ++ /* ++ * Flag used to decide whether to replace ++ * sd->next_in_service with new_entity. Tentatively ++ * set to true, and left as true if ++ * sd->next_in_service is NULL. ++ */ ++ change_without_lookup = true; ++ ++ /* ++ * If there is already a next_in_service candidate ++ * entity, then compare timestamps to decide whether ++ * to replace sd->service_tree with new_entity. ++ */ ++ if (next_in_service) { ++ unsigned int new_entity_class_idx = ++ bfq_class_idx(new_entity); ++ struct bfq_service_tree *st = ++ sd->service_tree + new_entity_class_idx; ++ ++ change_without_lookup = ++ (new_entity_class_idx == ++ bfq_class_idx(next_in_service) ++ && ++ !bfq_gt(new_entity->start, st->vtime) ++ && ++ bfq_gt(next_in_service->finish, ++ new_entity->finish)); ++ } ++ ++ if (change_without_lookup) { ++ next_in_service = new_entity; ++ bfqq = bfq_entity_to_bfqq(next_in_service); ++ ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "chose without lookup"); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(next_in_service, ++ struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data*)bfqg->bfqd, bfqg, ++ "chose without lookup"); ++ } ++#endif ++ } ++ } ++ ++ if (!change_without_lookup) /* lookup needed */ ++ next_in_service = bfq_lookup_next_entity(sd, expiration); ++ ++ if (next_in_service) { ++ bool new_budget_triggers_change = ++ bfq_update_parent_budget(next_in_service); ++ ++ parent_sched_may_change = !sd->next_in_service || ++ new_budget_triggers_change; ++ } ++ ++ sd->next_in_service = next_in_service; ++ ++ if (!next_in_service) ++ return parent_sched_may_change; ++ ++ bfqq = bfq_entity_to_bfqq(next_in_service); ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "chosen this queue"); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(next_in_service, ++ struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "chosen this entity"); ++ } ++#endif ++ return parent_sched_may_change; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++/* both next loops stop at one of the child entities of the root group */ ++#define for_each_entity(entity) \ ++ for (; entity ; entity = entity->parent) ++ ++/* ++ * For each iteration, compute parent in advance, so as to be safe if ++ * entity is deallocated during the iteration. Such a deallocation may ++ * happen as a consequence of a bfq_put_queue that frees the bfq_queue ++ * containing entity. ++ */ ++#define for_each_entity_safe(entity, parent) \ ++ for (; entity && ({ parent = entity->parent; 1; }); entity = parent) ++ ++/* ++ * Returns true if this budget changes may let next_in_service->parent ++ * become the next_in_service entity for its parent entity. ++ */ ++static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) ++{ ++ struct bfq_entity *bfqg_entity; ++ struct bfq_group *bfqg; ++ struct bfq_sched_data *group_sd; ++ bool ret = false; ++ ++ BUG_ON(!next_in_service); ++ ++ group_sd = next_in_service->sched_data; ++ ++ bfqg = container_of(group_sd, struct bfq_group, sched_data); ++ /* ++ * bfq_group's my_entity field is not NULL only if the group ++ * is not the root group. We must not touch the root entity ++ * as it must never become an in-service entity. ++ */ ++ bfqg_entity = bfqg->my_entity; ++ if (bfqg_entity) { ++ if (bfqg_entity->budget > next_in_service->budget) ++ ret = true; ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "old budg: %d, new budg: %d", ++ bfqg_entity->budget, next_in_service->budget); ++ bfqg_entity->budget = next_in_service->budget; ++ } ++ ++ return ret; ++} ++ ++/* ++ * This function tells whether entity stops being a candidate for next ++ * service, according to the restrictive definition of the field ++ * next_in_service. In particular, this function is invoked for an ++ * entity that is about to be set in service. ++ * ++ * If entity is a queue, then the entity is no longer a candidate for ++ * next service according to the that definition, because entity is ++ * about to become the in-service queue. This function then returns ++ * true if entity is a queue. ++ * ++ * In contrast, entity could still be a candidate for next service if ++ * it is not a queue, and has more than one active child. In fact, ++ * even if one of its children is about to be set in service, other ++ * active children may still be the next to serve, for the parent ++ * entity, even according to the above definition. As a consequence, a ++ * non-queue entity is not a candidate for next-service only if it has ++ * only one active child. And only if this condition holds, then this ++ * function returns true for a non-queue entity. ++ */ ++static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) ++{ ++ struct bfq_group *bfqg; ++ ++ if (bfq_entity_to_bfqq(entity)) ++ return true; ++ ++ bfqg = container_of(entity, struct bfq_group, entity); ++ ++ BUG_ON(bfqg == ((struct bfq_data *)(bfqg->bfqd))->root_group); ++ BUG_ON(bfqg->active_entities == 0); ++ /* ++ * The field active_entities does not always contain the ++ * actual number of active children entities: it happens to ++ * not account for the in-service entity in case the latter is ++ * removed from its active tree (which may get done after ++ * invoking the function bfq_no_longer_next_in_service in ++ * bfq_get_next_queue). Fortunately, here, i.e., while ++ * bfq_no_longer_next_in_service is not yet completed in ++ * bfq_get_next_queue, bfq_active_extract has not yet been ++ * invoked, and thus active_entities still coincides with the ++ * actual number of active entities. ++ */ ++ if (bfqg->active_entities == 1) ++ return true; ++ ++ return false; ++} ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++#define for_each_entity(entity) \ ++ for (; entity ; entity = NULL) ++ ++#define for_each_entity_safe(entity, parent) \ ++ for (parent = NULL; entity ; entity = parent) ++ ++static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) ++{ ++ return false; ++} ++ ++static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) ++{ ++ return true; ++} ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++/* ++ * Shift for timestamp calculations. This actually limits the maximum ++ * service allowed in one timestamp delta (small shift values increase it), ++ * the maximum total weight that can be used for the queues in the system ++ * (big shift values increase it), and the period of virtual time ++ * wraparounds. ++ */ ++#define WFQ_SERVICE_SHIFT 22 ++ ++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = NULL; ++ ++ BUG_ON(!entity); ++ ++ if (!entity->my_sched_data) ++ bfqq = container_of(entity, struct bfq_queue, entity); ++ ++ return bfqq; ++} ++ ++ ++/** ++ * bfq_delta - map service into the virtual time domain. ++ * @service: amount of service. ++ * @weight: scale factor (weight of an entity or weight sum). ++ */ ++static u64 bfq_delta(unsigned long service, unsigned long weight) ++{ ++ u64 d = (u64)service << WFQ_SERVICE_SHIFT; ++ ++ do_div(d, weight); ++ return d; ++} ++ ++/** ++ * bfq_calc_finish - assign the finish time to an entity. ++ * @entity: the entity to act upon. ++ * @service: the service to be charged to the entity. ++ */ ++static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned long long start, finish, delta; ++ ++ BUG_ON(entity->weight == 0); ++ ++ entity->finish = entity->start + ++ bfq_delta(service, entity->weight); ++ ++ start = ((entity->start>>10)*1000)>>12; ++ finish = ((entity->finish>>10)*1000)>>12; ++ delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12; ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "serv %lu, w %d", ++ service, entity->weight); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "start %llu, finish %llu, delta %llu", ++ start, finish, delta); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "group: serv %lu, w %d", ++ service, entity->weight); ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "group: start %llu, finish %llu, delta %llu", ++ start, finish, delta); ++#endif ++ } ++} ++ ++/** ++ * bfq_entity_of - get an entity from a node. ++ * @node: the node field of the entity. ++ * ++ * Convert a node pointer to the relative entity. This is used only ++ * to simplify the logic of some functions and not as the generic ++ * conversion mechanism because, e.g., in the tree walking functions, ++ * the check for a %NULL value would be redundant. ++ */ ++static struct bfq_entity *bfq_entity_of(struct rb_node *node) ++{ ++ struct bfq_entity *entity = NULL; ++ ++ if (node) ++ entity = rb_entry(node, struct bfq_entity, rb_node); ++ ++ return entity; ++} ++ ++/** ++ * bfq_extract - remove an entity from a tree. ++ * @root: the tree root. ++ * @entity: the entity to remove. ++ */ ++static void bfq_extract(struct rb_root *root, struct bfq_entity *entity) ++{ ++ BUG_ON(entity->tree != root); ++ ++ entity->tree = NULL; ++ rb_erase(&entity->rb_node, root); ++} ++ ++/** ++ * bfq_idle_extract - extract an entity from the idle tree. ++ * @st: the service tree of the owning @entity. ++ * @entity: the entity being removed. ++ */ ++static void bfq_idle_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *next; ++ ++ BUG_ON(entity->tree != &st->idle); ++ ++ if (entity == st->first_idle) { ++ next = rb_next(&entity->rb_node); ++ st->first_idle = bfq_entity_of(next); ++ } ++ ++ if (entity == st->last_idle) { ++ next = rb_prev(&entity->rb_node); ++ st->last_idle = bfq_entity_of(next); ++ } ++ ++ bfq_extract(&st->idle, entity); ++ ++ if (bfqq) ++ list_del(&bfqq->bfqq_list); ++} ++ ++/** ++ * bfq_insert - generic tree insertion. ++ * @root: tree root. ++ * @entity: entity to insert. ++ * ++ * This is used for the idle and the active tree, since they are both ++ * ordered by finish time. ++ */ ++static void bfq_insert(struct rb_root *root, struct bfq_entity *entity) ++{ ++ struct bfq_entity *entry; ++ struct rb_node **node = &root->rb_node; ++ struct rb_node *parent = NULL; ++ ++ BUG_ON(entity->tree); ++ ++ while (*node) { ++ parent = *node; ++ entry = rb_entry(parent, struct bfq_entity, rb_node); ++ ++ if (bfq_gt(entry->finish, entity->finish)) ++ node = &parent->rb_left; ++ else ++ node = &parent->rb_right; ++ } ++ ++ rb_link_node(&entity->rb_node, parent, node); ++ rb_insert_color(&entity->rb_node, root); ++ ++ entity->tree = root; ++} ++ ++/** ++ * bfq_update_min - update the min_start field of a entity. ++ * @entity: the entity to update. ++ * @node: one of its children. ++ * ++ * This function is called when @entity may store an invalid value for ++ * min_start due to updates to the active tree. The function assumes ++ * that the subtree rooted at @node (which may be its left or its right ++ * child) has a valid min_start value. ++ */ ++static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node) ++{ ++ struct bfq_entity *child; ++ ++ if (node) { ++ child = rb_entry(node, struct bfq_entity, rb_node); ++ if (bfq_gt(entity->min_start, child->min_start)) ++ entity->min_start = child->min_start; ++ } ++} ++ ++/** ++ * bfq_update_active_node - recalculate min_start. ++ * @node: the node to update. ++ * ++ * @node may have changed position or one of its children may have moved, ++ * this function updates its min_start value. The left and right subtrees ++ * are assumed to hold a correct min_start value. ++ */ ++static void bfq_update_active_node(struct rb_node *node) ++{ ++ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node); ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ entity->min_start = entity->start; ++ bfq_update_min(entity, node->rb_right); ++ bfq_update_min(entity, node->rb_left); ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "new min_start %llu", ++ ((entity->min_start>>10)*1000)>>12); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "new min_start %llu", ++ ((entity->min_start>>10)*1000)>>12); ++#endif ++ } ++} ++ ++/** ++ * bfq_update_active_tree - update min_start for the whole active tree. ++ * @node: the starting node. ++ * ++ * @node must be the deepest modified node after an update. This function ++ * updates its min_start using the values held by its children, assuming ++ * that they did not change, and then updates all the nodes that may have ++ * changed in the path to the root. The only nodes that may have changed ++ * are the ones in the path or their siblings. ++ */ ++static void bfq_update_active_tree(struct rb_node *node) ++{ ++ struct rb_node *parent; ++ ++up: ++ bfq_update_active_node(node); ++ ++ parent = rb_parent(node); ++ if (!parent) ++ return; ++ ++ if (node == parent->rb_left && parent->rb_right) ++ bfq_update_active_node(parent->rb_right); ++ else if (parent->rb_left) ++ bfq_update_active_node(parent->rb_left); ++ ++ node = parent; ++ goto up; ++} ++ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root); ++ ++static void __bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root); ++ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq); ++ ++ ++/** ++ * bfq_active_insert - insert an entity in the active tree of its ++ * group/device. ++ * @st: the service tree of the entity. ++ * @entity: the entity being inserted. ++ * ++ * The active tree is ordered by finish time, but an extra key is kept ++ * per each node, containing the minimum value for the start times of ++ * its children (and the node itself), so it's possible to search for ++ * the eligible node with the lowest finish time in logarithmic time. ++ */ ++static void bfq_active_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node = &entity->rb_node; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ bfq_insert(&st->active, entity); ++ ++ if (node->rb_left) ++ node = node->rb_left; ++ else if (node->rb_right) ++ node = node->rb_right; ++ ++ bfq_update_active_tree(node); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ bfqg->active_entities++; ++ } ++#endif ++} ++ ++/** ++ * bfq_ioprio_to_weight - calc a weight from an ioprio. ++ * @ioprio: the ioprio value to convert. ++ */ ++static unsigned short bfq_ioprio_to_weight(int ioprio) ++{ ++ BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR); ++ return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF; ++} ++ ++/** ++ * bfq_weight_to_ioprio - calc an ioprio from a weight. ++ * @weight: the weight value to convert. ++ * ++ * To preserve as much as possible the old only-ioprio user interface, ++ * 0 is used as an escape ioprio value for weights (numerically) equal or ++ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF. ++ */ ++static unsigned short bfq_weight_to_ioprio(int weight) ++{ ++ BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT); ++ return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ? ++ 0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight; ++} ++ ++static void bfq_get_entity(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ if (bfqq) { ++ bfqq->ref++; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", ++ bfqq, bfqq->ref); ++ } ++} ++ ++/** ++ * bfq_find_deepest - find the deepest node that an extraction can modify. ++ * @node: the node being removed. ++ * ++ * Do the first step of an extraction in an rb tree, looking for the ++ * node that will replace @node, and returning the deepest node that ++ * the following modifications to the tree can touch. If @node is the ++ * last node in the tree return %NULL. ++ */ ++static struct rb_node *bfq_find_deepest(struct rb_node *node) ++{ ++ struct rb_node *deepest; ++ ++ if (!node->rb_right && !node->rb_left) ++ deepest = rb_parent(node); ++ else if (!node->rb_right) ++ deepest = node->rb_left; ++ else if (!node->rb_left) ++ deepest = node->rb_right; ++ else { ++ deepest = rb_next(node); ++ if (deepest->rb_right) ++ deepest = deepest->rb_right; ++ else if (rb_parent(deepest) != node) ++ deepest = rb_parent(deepest); ++ } ++ ++ return deepest; ++} ++ ++/** ++ * bfq_active_extract - remove an entity from the active tree. ++ * @st: the service_tree containing the tree. ++ * @entity: the entity being removed. ++ */ ++static void bfq_active_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ node = bfq_find_deepest(&entity->rb_node); ++ bfq_extract(&st->active, entity); ++ ++ if (node) ++ bfq_update_active_tree(node); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq) ++ list_del(&bfqq->bfqq_list); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ BUG_ON(!bfqg->active_entities); ++ bfqg->active_entities--; ++ } ++#endif ++} ++ ++/** ++ * bfq_idle_insert - insert an entity into the idle tree. ++ * @st: the service tree containing the tree. ++ * @entity: the entity to insert. ++ */ ++static void bfq_idle_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (!first_idle || bfq_gt(first_idle->finish, entity->finish)) ++ st->first_idle = entity; ++ if (!last_idle || bfq_gt(entity->finish, last_idle->finish)) ++ st->last_idle = entity; ++ ++ bfq_insert(&st->idle, entity); ++ ++ if (bfqq) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); ++} ++ ++/** ++ * bfq_forget_entity - do not consider entity any longer for scheduling ++ * @st: the service tree. ++ * @entity: the entity being removed. ++ * @is_in_service: true if entity is currently the in-service entity. ++ * ++ * Forget everything about @entity. In addition, if entity represents ++ * a queue, and the latter is not in service, then release the service ++ * reference to the queue (the one taken through bfq_get_entity). In ++ * fact, in this case, there is really no more service reference to ++ * the queue, as the latter is also outside any service tree. If, ++ * instead, the queue is in service, then __bfq_bfqd_reset_in_service ++ * will take care of putting the reference when the queue finally ++ * stops being served. ++ */ ++static void bfq_forget_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity, ++ bool is_in_service) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ BUG_ON(!entity->on_st); ++ ++ entity->on_st = false; ++ st->wsum -= entity->weight; ++ if (bfqq && !is_in_service) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "(before): %p %d", ++ bfqq, bfqq->ref); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++/** ++ * bfq_put_idle_entity - release the idle tree ref of an entity. ++ * @st: service tree for the entity. ++ * @entity: the entity being released. ++ */ ++static void bfq_put_idle_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ bfq_idle_extract(st, entity); ++ bfq_forget_entity(st, entity, ++ entity == entity->sched_data->in_service_entity); ++} ++ ++/** ++ * bfq_forget_idle - update the idle tree if necessary. ++ * @st: the service tree to act upon. ++ * ++ * To preserve the global O(log N) complexity we only remove one entry here; ++ * as the idle tree will not grow indefinitely this can be done safely. ++ */ ++static void bfq_forget_idle(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (RB_EMPTY_ROOT(&st->active) && last_idle && ++ !bfq_gt(last_idle->finish, st->vtime)) { ++ /* ++ * Forget the whole idle tree, increasing the vtime past ++ * the last finish time of idle entities. ++ */ ++ st->vtime = last_idle->finish; ++ } ++ ++ if (first_idle && !bfq_gt(first_idle->finish, st->vtime)) ++ bfq_put_idle_entity(st, first_idle); ++} ++ ++/* ++ * Update weight and priority of entity. If update_class_too is true, ++ * then update the ioprio_class of entity too. ++ * ++ * The reason why the update of ioprio_class is controlled through the ++ * last parameter is as follows. Changing the ioprio class of an ++ * entity implies changing the destination service trees for that ++ * entity. If such a change occurred when the entity is already on one ++ * of the service trees for its previous class, then the state of the ++ * entity would become more complex: none of the new possible service ++ * trees for the entity, according to bfq_entity_service_tree(), would ++ * match any of the possible service trees on which the entity ++ * is. Complex operations involving these trees, such as entity ++ * activations and deactivations, should take into account this ++ * additional complexity. To avoid this issue, this function is ++ * invoked with update_class_too unset in the points in the code where ++ * entity may happen to be on some tree. ++ */ ++static struct bfq_service_tree * ++__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, ++ struct bfq_entity *entity, ++ bool update_class_too) ++{ ++ struct bfq_service_tree *new_st = old_st; ++ ++ if (entity->prio_changed) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned int prev_weight, new_weight; ++ struct bfq_data *bfqd = NULL; ++ struct rb_root *root; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ struct bfq_sched_data *sd; ++ struct bfq_group *bfqg; ++#endif ++ ++ if (bfqq) ++ bfqd = bfqq->bfqd; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ sd = entity->my_sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++ BUG_ON(!bfqd); ++ } ++#endif ++ ++ BUG_ON(entity->tree && update_class_too); ++ BUG_ON(old_st->wsum < entity->weight); ++ old_st->wsum -= entity->weight; ++ ++ if (entity->new_weight != entity->orig_weight) { ++ if (entity->new_weight < BFQ_MIN_WEIGHT || ++ entity->new_weight > BFQ_MAX_WEIGHT) { ++ pr_crit("update_weight_prio: new_weight %d\n", ++ entity->new_weight); ++ if (entity->new_weight < BFQ_MIN_WEIGHT) ++ entity->new_weight = BFQ_MIN_WEIGHT; ++ else ++ entity->new_weight = BFQ_MAX_WEIGHT; ++ } ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) ++ bfqq->ioprio = ++ bfq_weight_to_ioprio(entity->orig_weight); ++ } ++ ++ if (bfqq && update_class_too) ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++ ++ /* ++ * Reset prio_changed only if the ioprio_class change ++ * is not pending any longer. ++ */ ++ if (!bfqq || bfqq->ioprio_class == bfqq->new_ioprio_class) ++ entity->prio_changed = 0; ++ ++ /* ++ * NOTE: here we may be changing the weight too early, ++ * this will cause unfairness. The correct approach ++ * would have required additional complexity to defer ++ * weight changes to the proper time instants (i.e., ++ * when entity->finish <= old_st->vtime). ++ */ ++ new_st = bfq_entity_service_tree(entity); ++ ++ prev_weight = entity->weight; ++ new_weight = entity->orig_weight * ++ (bfqq ? bfqq->wr_coeff : 1); ++ /* ++ * If the weight of the entity changes and the entity is a ++ * queue, remove the entity from its old weight counter (if ++ * there is a counter associated with the entity). ++ */ ++ if (prev_weight != new_weight && bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "weight changed %d %d(%d %d)", ++ prev_weight, new_weight, ++ entity->orig_weight, ++ bfqq->wr_coeff); ++ ++ root = &bfqd->queue_weights_tree; ++ __bfq_weights_tree_remove(bfqd, bfqq, root); ++ } ++ entity->weight = new_weight; ++ /* ++ * Add the entity, if it is not a weight-raised queue, to the ++ * counter associated with its new weight. ++ */ ++ if (prev_weight != new_weight && bfqq && bfqq->wr_coeff == 1) { ++ /* If we get here, root has been initialized. */ ++ bfq_weights_tree_add(bfqd, bfqq, root); ++ } ++ ++ new_st->wsum += entity->weight; ++ ++ if (new_st != old_st) { ++ BUG_ON(!update_class_too); ++ entity->start = new_st->vtime; ++ } ++ } ++ ++ return new_st; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); ++#endif ++ ++/** ++ * bfq_bfqq_served - update the scheduler status after selection for ++ * service. ++ * @bfqq: the queue being served. ++ * @served: bytes to transfer. ++ * ++ * NOTE: this can be optimized, as the timestamps of upper level entities ++ * are synchronized every time a new bfqq is selected for service. By now, ++ * we keep it to better check consistency. ++ */ ++static void bfq_bfqq_served(struct bfq_queue *bfqq, int served) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st; ++ ++ if (!bfqq->service_from_backlogged) ++ bfqq->first_IO_time = jiffies; ++ ++ if (bfqq->wr_coeff > 1) ++ bfqq->service_from_wr += served; ++ ++ bfqq->service_from_backlogged += served; ++ for_each_entity(entity) { ++ st = bfq_entity_service_tree(entity); ++ ++ entity->service += served; ++ ++ BUG_ON(st->wsum == 0); ++ ++ st->vtime += bfq_delta(served, st->wsum); ++ bfq_forget_idle(st); ++ } ++#ifndef BFQ_MQ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); ++#endif ++#endif ++ st = bfq_entity_service_tree(&bfqq->entity); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p", ++ served, ((st->vtime>>10)*1000)>>12, st); ++} ++ ++/** ++ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length ++ * of the time interval during which bfqq has been in ++ * service. ++ * @bfqd: the device ++ * @bfqq: the queue that needs a service update. ++ * @time_ms: the amount of time during which the queue has received service ++ * ++ * If a queue does not consume its budget fast enough, then providing ++ * the queue with service fairness may impair throughput, more or less ++ * severely. For this reason, queues that consume their budget slowly ++ * are provided with time fairness instead of service fairness. This ++ * goal is achieved through the BFQ scheduling engine, even if such an ++ * engine works in the service, and not in the time domain. The trick ++ * is charging these queues with an inflated amount of service, equal ++ * to the amount of service that they would have received during their ++ * service slot if they had been fast, i.e., if their requests had ++ * been dispatched at a rate equal to the estimated peak rate. ++ * ++ * It is worth noting that time fairness can cause important ++ * distortions in terms of bandwidth distribution, on devices with ++ * internal queueing. The reason is that I/O requests dispatched ++ * during the service slot of a queue may be served after that service ++ * slot is finished, and may have a total processing time loosely ++ * correlated with the duration of the service slot. This is ++ * especially true for short service slots. ++ */ ++static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ unsigned long time_ms) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ unsigned long timeout_ms = jiffies_to_msecs(bfq_timeout); ++ unsigned long bounded_time_ms = min(time_ms, timeout_ms); ++ int serv_to_charge_for_time = ++ (bfqd->bfq_max_budget * bounded_time_ms) / timeout_ms; ++ int tot_serv_to_charge = max(serv_to_charge_for_time, entity->service); ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "%lu/%lu ms, %d/%d/%d/%d sectors", ++ time_ms, timeout_ms, ++ entity->service, ++ tot_serv_to_charge, ++ bfqd->bfq_max_budget, ++ entity->budget); ++ ++ /* Increase budget to avoid inconsistencies */ ++ if (tot_serv_to_charge > entity->budget) ++ entity->budget = tot_serv_to_charge; ++ ++ bfq_bfqq_served(bfqq, ++ max_t(int, 0, tot_serv_to_charge - entity->service)); ++} ++ ++static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, ++ struct bfq_service_tree *st, ++ bool backshifted) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_sched_data *sd = entity->sched_data; ++ ++ /* ++ * When this function is invoked, entity is not in any service ++ * tree, then it is safe to invoke next function with the last ++ * parameter set (see the comments on the function). ++ */ ++ BUG_ON(entity->tree); ++ st = __bfq_entity_update_weight_prio(st, entity, true); ++ bfq_calc_finish(entity, entity->budget); ++ ++ /* ++ * If some queues enjoy backshifting for a while, then their ++ * (virtual) finish timestamps may happen to become lower and ++ * lower than the system virtual time. In particular, if ++ * these queues often happen to be idle for short time ++ * periods, and during such time periods other queues with ++ * higher timestamps happen to be busy, then the backshifted ++ * timestamps of the former queues can become much lower than ++ * the system virtual time. In fact, to serve the queues with ++ * higher timestamps while the ones with lower timestamps are ++ * idle, the system virtual time may be pushed-up to much ++ * higher values than the finish timestamps of the idle ++ * queues. As a consequence, the finish timestamps of all new ++ * or newly activated queues may end up being much larger than ++ * those of lucky queues with backshifted timestamps. The ++ * latter queues may then monopolize the device for a lot of ++ * time. This would simply break service guarantees. ++ * ++ * To reduce this problem, push up a little bit the ++ * backshifted timestamps of the queue associated with this ++ * entity (only a queue can happen to have the backshifted ++ * flag set): just enough to let the finish timestamp of the ++ * queue be equal to the current value of the system virtual ++ * time. This may introduce a little unfairness among queues ++ * with backshifted timestamps, but it does not break ++ * worst-case fairness guarantees. ++ * ++ * As a special case, if bfqq is weight-raised, push up ++ * timestamps much less, to keep very low the probability that ++ * this push up causes the backshifted finish timestamps of ++ * weight-raised queues to become higher than the backshifted ++ * finish timestamps of non weight-raised queues. ++ */ ++ if (backshifted && bfq_gt(st->vtime, entity->finish)) { ++ unsigned long delta = st->vtime - entity->finish; ++ ++ if (bfqq) ++ delta /= bfqq->wr_coeff; ++ ++ entity->start += delta; ++ entity->finish += delta; ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "new queue finish %llu", ++ ((entity->finish>>10)*1000)>>12); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "new group finish %llu", ++ ((entity->finish>>10)*1000)>>12); ++#endif ++ } ++ } ++ ++ bfq_active_insert(st, entity); ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "queue %seligible in st %p", ++ entity->start <= st->vtime ? "" : "non ", st); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "group %seligible in st %p", ++ entity->start <= st->vtime ? "" : "non ", st); ++#endif ++ } ++ BUG_ON(RB_EMPTY_ROOT(&st->active)); ++ BUG_ON(&st->active != &sd->service_tree->active && ++ &st->active != &(sd->service_tree+1)->active && ++ &st->active != &(sd->service_tree+2)->active); ++} ++ ++/** ++ * __bfq_activate_entity - handle activation of entity. ++ * @entity: the entity being activated. ++ * @non_blocking_wait_rq: true if entity was waiting for a request ++ * ++ * Called for a 'true' activation, i.e., if entity is not active and ++ * one of its children receives a new request. ++ * ++ * Basically, this function updates the timestamps of entity and ++ * inserts entity into its active tree, after possibly extracting it ++ * from its idle tree. ++ */ ++static void __bfq_activate_entity(struct bfq_entity *entity, ++ bool non_blocking_wait_rq) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ bool backshifted = false; ++ unsigned long long min_vstart; ++ ++ BUG_ON(!sd); ++ BUG_ON(!st); ++ ++ /* See comments on bfq_fqq_update_budg_for_activation */ ++ if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) { ++ backshifted = true; ++ min_vstart = entity->finish; ++ } else ++ min_vstart = st->vtime; ++ ++ if (entity->tree == &st->idle) { ++ /* ++ * Must be on the idle tree, bfq_idle_extract() will ++ * check for that. ++ */ ++ bfq_idle_extract(st, entity); ++ BUG_ON(entity->tree); ++ entity->start = bfq_gt(min_vstart, entity->finish) ? ++ min_vstart : entity->finish; ++ } else { ++ BUG_ON(entity->tree); ++ /* ++ * The finish time of the entity may be invalid, and ++ * it is in the past for sure, otherwise the queue ++ * would have been on the idle tree. ++ */ ++ entity->start = min_vstart; ++ st->wsum += entity->weight; ++ /* ++ * entity is about to be inserted into a service tree, ++ * and then set in service: get a reference to make ++ * sure entity does not disappear until it is no ++ * longer in service or scheduled for service. ++ */ ++ bfq_get_entity(entity); ++ ++ BUG_ON(entity->on_st && bfqq); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ if (entity->on_st && !bfqq) { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, ++ entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, ++ bfqg, ++ "activate bug, class %d in_service %p", ++ bfq_class_idx(entity), sd->in_service_entity); ++ } ++#endif ++ BUG_ON(entity->on_st && !bfqq); ++ entity->on_st = true; ++ } ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */ ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ struct bfq_data *bfqd = bfqg->bfqd; ++ ++ BUG_ON(!bfqd); ++ if (!entity->in_groups_with_pending_reqs) { ++ entity->in_groups_with_pending_reqs = true; ++ bfqd->num_groups_with_pending_reqs++; ++ } ++ bfq_log_bfqg(bfqd, bfqg, "num_groups_with_pending_reqs %u", ++ bfqd->num_groups_with_pending_reqs); ++ } ++#endif ++ ++ bfq_update_fin_time_enqueue(entity, st, backshifted); ++} ++ ++/** ++ * __bfq_requeue_entity - handle requeueing or repositioning of an entity. ++ * @entity: the entity being requeued or repositioned. ++ * ++ * Requeueing is needed if this entity stops being served, which ++ * happens if a leaf descendant entity has expired. On the other hand, ++ * repositioning is needed if the next_inservice_entity for the child ++ * entity has changed. See the comments inside the function for ++ * details. ++ * ++ * Basically, this function: 1) removes entity from its active tree if ++ * present there, 2) updates the timestamps of entity and 3) inserts ++ * entity back into its active tree (in the new, right position for ++ * the new values of the timestamps). ++ */ ++static void __bfq_requeue_entity(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ ++ BUG_ON(!sd); ++ BUG_ON(!st); ++ ++ BUG_ON(entity != sd->in_service_entity && ++ entity->tree != &st->active); ++ ++ if (entity == sd->in_service_entity) { ++ /* ++ * We are requeueing the current in-service entity, ++ * which may have to be done for one of the following ++ * reasons: ++ * - entity represents the in-service queue, and the ++ * in-service queue is being requeued after an ++ * expiration; ++ * - entity represents a group, and its budget has ++ * changed because one of its child entities has ++ * just been either activated or requeued for some ++ * reason; the timestamps of the entity need then to ++ * be updated, and the entity needs to be enqueued ++ * or repositioned accordingly. ++ * ++ * In particular, before requeueing, the start time of ++ * the entity must be moved forward to account for the ++ * service that the entity has received while in ++ * service. This is done by the next instructions. The ++ * finish time will then be updated according to this ++ * new value of the start time, and to the budget of ++ * the entity. ++ */ ++ bfq_calc_finish(entity, entity->service); ++ entity->start = entity->finish; ++ BUG_ON(entity->tree && entity->tree == &st->idle); ++ BUG_ON(entity->tree && entity->tree != &st->active); ++ /* ++ * In addition, if the entity had more than one child ++ * when set in service, then it was not extracted from ++ * the active tree. This implies that the position of ++ * the entity in the active tree may need to be ++ * changed now, because we have just updated the start ++ * time of the entity, and we will update its finish ++ * time in a moment (the requeueing is then, more ++ * precisely, a repositioning in this case). To ++ * implement this repositioning, we: 1) dequeue the ++ * entity here, 2) update the finish time and requeue ++ * the entity according to the new timestamps below. ++ */ ++ if (entity->tree) ++ bfq_active_extract(st, entity); ++ } else { /* The entity is already active, and not in service */ ++ /* ++ * In this case, this function gets called only if the ++ * next_in_service entity below this entity has ++ * changed, and this change has caused the budget of ++ * this entity to change, which, finally implies that ++ * the finish time of this entity must be ++ * updated. Such an update may cause the scheduling, ++ * i.e., the position in the active tree, of this ++ * entity to change. We handle this change by: 1) ++ * dequeueing the entity here, 2) updating the finish ++ * time and requeueing the entity according to the new ++ * timestamps below. This is the same approach as the ++ * non-extracted-entity sub-case above. ++ */ ++ bfq_active_extract(st, entity); ++ } ++ ++ bfq_update_fin_time_enqueue(entity, st, false); ++} ++ ++static void __bfq_activate_requeue_entity(struct bfq_entity *entity, ++ struct bfq_sched_data *sd, ++ bool non_blocking_wait_rq) ++{ ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ ++ if (sd->in_service_entity == entity || entity->tree == &st->active) ++ /* ++ * in service or already queued on the active tree, ++ * requeue or reposition ++ */ ++ __bfq_requeue_entity(entity); ++ else ++ /* ++ * Not in service and not queued on its active tree: ++ * the activity is idle and this is a true activation. ++ */ ++ __bfq_activate_entity(entity, non_blocking_wait_rq); ++} ++ ++ ++/** ++ * bfq_activate_requeue_entity - activate or requeue an entity representing a bfq_queue, ++ * and activate, requeue or reposition all ancestors ++ * for which such an update becomes necessary. ++ * @entity: the entity to activate. ++ * @non_blocking_wait_rq: true if this entity was waiting for a request ++ * @requeue: true if this is a requeue, which implies that bfqq is ++ * being expired; thus ALL its ancestors stop being served and must ++ * therefore be requeued ++ * @expiration: true if this function is being invoked in the expiration path ++ * of the in-service queue ++ */ ++static void bfq_activate_requeue_entity(struct bfq_entity *entity, ++ bool non_blocking_wait_rq, ++ bool requeue, bool expiration) ++{ ++ struct bfq_sched_data *sd; ++ ++ for_each_entity(entity) { ++ BUG_ON(!entity); ++ sd = entity->sched_data; ++ __bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq); ++ ++ BUG_ON(RB_EMPTY_ROOT(&sd->service_tree->active) && ++ RB_EMPTY_ROOT(&(sd->service_tree+1)->active) && ++ RB_EMPTY_ROOT(&(sd->service_tree+2)->active)); ++ ++ if (!bfq_update_next_in_service(sd, entity, expiration) && ++ !requeue) { ++ BUG_ON(!sd->next_in_service); ++ break; ++ } ++ BUG_ON(!sd->next_in_service); ++ } ++} ++ ++/** ++ * __bfq_deactivate_entity - update sched_data and service trees for ++ * entity, so as to represent entity as inactive ++ * @entity: the entity being deactivated. ++ * @ins_into_idle_tree: if false, the entity will not be put into the ++ * idle tree. ++ * ++ * If necessary and allowed, puts entity into the idle tree. NOTE: ++ * entity may be on no tree if in service. ++ */ ++static bool __bfq_deactivate_entity(struct bfq_entity *entity, ++ bool ins_into_idle_tree) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st; ++ bool is_in_service; ++ ++ if (!entity->on_st) { /* entity never activated, or already inactive */ ++ BUG_ON(sd && entity == sd->in_service_entity); ++ return false; ++ } ++ ++ /* ++ * If we get here, then entity is active, which implies that ++ * bfq_group_set_parent has already been invoked for the group ++ * represented by entity. Therefore, the field ++ * entity->sched_data has been set, and we can safely use it. ++ */ ++ st = bfq_entity_service_tree(entity); ++ is_in_service = entity == sd->in_service_entity; ++ ++ BUG_ON(is_in_service && entity->tree && entity->tree != &st->active); ++ ++ bfq_calc_finish(entity, entity->service); ++ ++ if (is_in_service) { ++ sd->in_service_entity = NULL; ++ } else ++ /* ++ * Non in-service entity: nobody will take care of ++ * resetting its service counter on expiration. Do it ++ * now. ++ */ ++ entity->service = 0; ++ ++ if (entity->tree == &st->active) ++ bfq_active_extract(st, entity); ++ else if (!is_in_service && entity->tree == &st->idle) ++ bfq_idle_extract(st, entity); ++ else if (entity->tree) ++ BUG(); ++ ++ if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime)) ++ bfq_forget_entity(st, entity, is_in_service); ++ else ++ bfq_idle_insert(st, entity); ++ ++ return true; ++} ++ ++/** ++ * bfq_deactivate_entity - deactivate an entity representing a bfq_queue. ++ * @entity: the entity to deactivate. ++ * @ins_into_idle_tree: true if the entity can be put into the idle tree ++ * @expiration: true if this function is being invoked in the expiration path ++ * of the in-service queue ++ */ ++static void bfq_deactivate_entity(struct bfq_entity *entity, ++ bool ins_into_idle_tree, ++ bool expiration) ++{ ++ struct bfq_sched_data *sd; ++ struct bfq_entity *parent = NULL; ++ ++ for_each_entity_safe(entity, parent) { ++ sd = entity->sched_data; ++ ++ BUG_ON(sd == NULL); /* ++ * It would mean that this is the ++ * root group. ++ */ ++ ++ BUG_ON(expiration && entity != sd->in_service_entity); ++ ++ BUG_ON(entity != sd->in_service_entity && ++ entity->tree == ++ &bfq_entity_service_tree(entity)->active && ++ !sd->next_in_service); ++ ++ if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) { ++ /* ++ * entity is not in any tree any more, so ++ * this deactivation is a no-op, and there is ++ * nothing to change for upper-level entities ++ * (in case of expiration, this can never ++ * happen). ++ */ ++ BUG_ON(expiration); /* ++ * entity cannot be already out of ++ * any tree ++ */ ++ return; ++ } ++ ++ if (sd->next_in_service == entity) ++ /* ++ * entity was the next_in_service entity, ++ * then, since entity has just been ++ * deactivated, a new one must be found. ++ */ ++ bfq_update_next_in_service(sd, NULL, expiration); ++ ++ if (sd->next_in_service || sd->in_service_entity) { ++ /* ++ * The parent entity is still active, because ++ * either next_in_service or in_service_entity ++ * is not NULL. So, no further upwards ++ * deactivation must be performed. Yet, ++ * next_in_service has changed. Then the ++ * schedule does need to be updated upwards. ++ * ++ * NOTE If in_service_entity is not NULL, then ++ * next_in_service may happen to be NULL, ++ * although the parent entity is evidently ++ * active. This happens if 1) the entity ++ * pointed by in_service_entity is the only ++ * active entity in the parent entity, and 2) ++ * according to the definition of ++ * next_in_service, the in_service_entity ++ * cannot be considered as ++ * next_in_service. See the comments on the ++ * definition of next_in_service for details. ++ */ ++ BUG_ON(sd->next_in_service == entity); ++ BUG_ON(sd->in_service_entity == entity); ++ break; ++ } ++ ++ /* ++ * If we get here, then the parent is no more ++ * backlogged and we need to propagate the ++ * deactivation upwards. Thus let the loop go on. ++ */ ++ ++ /* ++ * Also let parent be queued into the idle tree on ++ * deactivation, to preserve service guarantees, and ++ * assuming that who invoked this function does not ++ * need parent entities too to be removed completely. ++ */ ++ ins_into_idle_tree = true; ++ } ++ ++ /* ++ * If the deactivation loop is fully executed, then there are ++ * no more entities to touch and next loop is not executed at ++ * all. Otherwise, requeue remaining entities if they are ++ * about to stop receiving service, or reposition them if this ++ * is not the case. ++ */ ++ entity = parent; ++ for_each_entity(entity) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ /* ++ * Invoke __bfq_requeue_entity on entity, even if ++ * already active, to requeue/reposition it in the ++ * active tree (because sd->next_in_service has ++ * changed) ++ */ ++ __bfq_requeue_entity(entity); ++ ++ sd = entity->sched_data; ++ BUG_ON(expiration && sd->in_service_entity != entity); ++ ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "invoking udpdate_next for this queue"); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, ++ struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "invoking udpdate_next for this entity"); ++ } ++#endif ++ if (!bfq_update_next_in_service(sd, entity, expiration) && ++ !expiration) ++ /* ++ * next_in_service unchanged or not causing ++ * any change in entity->parent->sd, and no ++ * requeueing needed for expiration: stop ++ * here. ++ */ ++ break; ++ } ++} ++ ++/** ++ * bfq_calc_vtime_jump - compute the value to which the vtime should jump, ++ * if needed, to have at least one entity eligible. ++ * @st: the service tree to act upon. ++ * ++ * Assumes that st is not empty. ++ */ ++static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *root_entity = bfq_root_active_entity(&st->active); ++ ++ if (bfq_gt(root_entity->min_start, st->vtime)) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(root_entity); ++ ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "new value %llu", ++ ((root_entity->min_start>>10)*1000)>>12); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(root_entity, struct bfq_group, ++ entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "new value %llu", ++ ((root_entity->min_start>>10)*1000)>>12); ++ } ++#endif ++ return root_entity->min_start; ++ } ++ return st->vtime; ++} ++ ++static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value) ++{ ++ if (new_value > st->vtime) { ++ st->vtime = new_value; ++ bfq_forget_idle(st); ++ } ++} ++ ++/** ++ * bfq_first_active_entity - find the eligible entity with ++ * the smallest finish time ++ * @st: the service tree to select from. ++ * @vtime: the system virtual to use as a reference for eligibility ++ * ++ * This function searches the first schedulable entity, starting from the ++ * root of the tree and going on the left every time on this side there is ++ * a subtree with at least one eligible (start >= vtime) entity. The path on ++ * the right is followed only if a) the left subtree contains no eligible ++ * entities and b) no eligible entity has been found yet. ++ */ ++static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st, ++ u64 vtime) ++{ ++ struct bfq_entity *entry, *first = NULL; ++ struct rb_node *node = st->active.rb_node; ++ ++ while (node) { ++ entry = rb_entry(node, struct bfq_entity, rb_node); ++left: ++ if (!bfq_gt(entry->start, vtime)) ++ first = entry; ++ ++ BUG_ON(bfq_gt(entry->min_start, vtime)); ++ ++ if (node->rb_left) { ++ entry = rb_entry(node->rb_left, ++ struct bfq_entity, rb_node); ++ if (!bfq_gt(entry->min_start, vtime)) { ++ node = node->rb_left; ++ goto left; ++ } ++ } ++ if (first) ++ break; ++ node = node->rb_right; ++ } ++ ++ BUG_ON(!first && !RB_EMPTY_ROOT(&st->active)); ++ return first; ++} ++ ++/** ++ * __bfq_lookup_next_entity - return the first eligible entity in @st. ++ * @st: the service tree. ++ * ++ * If there is no in-service entity for the sched_data st belongs to, ++ * then return the entity that will be set in service if: ++ * 1) the parent entity this st belongs to is set in service; ++ * 2) no entity belonging to such parent entity undergoes a state change ++ * that would influence the timestamps of the entity (e.g., becomes idle, ++ * becomes backlogged, changes its budget, ...). ++ * ++ * In this first case, update the virtual time in @st too (see the ++ * comments on this update inside the function). ++ * ++ * In constrast, if there is an in-service entity, then return the ++ * entity that would be set in service if not only the above ++ * conditions, but also the next one held true: the currently ++ * in-service entity, on expiration, ++ * 1) gets a finish time equal to the current one, or ++ * 2) is not eligible any more, or ++ * 3) is idle. ++ */ ++static struct bfq_entity * ++__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service) ++{ ++ struct bfq_entity *entity; ++ u64 new_vtime; ++ struct bfq_queue *bfqq; ++ ++ if (RB_EMPTY_ROOT(&st->active)) ++ return NULL; ++ ++ /* ++ * Get the value of the system virtual time for which at ++ * least one entity is eligible. ++ */ ++ new_vtime = bfq_calc_vtime_jump(st); ++ ++ /* ++ * If there is no in-service entity for the sched_data this ++ * active tree belongs to, then push the system virtual time ++ * up to the value that guarantees that at least one entity is ++ * eligible. If, instead, there is an in-service entity, then ++ * do not make any such update, because there is already an ++ * eligible entity, namely the in-service one (even if the ++ * entity is not on st, because it was extracted when set in ++ * service). ++ */ ++ if (!in_service) ++ bfq_update_vtime(st, new_vtime); ++ ++ entity = bfq_first_active_entity(st, new_vtime); ++ BUG_ON(bfq_gt(entity->start, new_vtime)); ++ ++ /* Log some information */ ++ bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "start %llu vtime %llu st %p", ++ ((entity->start>>10)*1000)>>12, ++ ((new_vtime>>10)*1000)>>12, st); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "start %llu vtime %llu (%llu) st %p", ++ ((entity->start>>10)*1000)>>12, ++ ((st->vtime>>10)*1000)>>12, ++ ((new_vtime>>10)*1000)>>12, st); ++ } ++#endif ++ ++ BUG_ON(!entity); ++ ++ return entity; ++} ++ ++/** ++ * bfq_lookup_next_entity - return the first eligible entity in @sd. ++ * @sd: the sched_data. ++ * @expiration: true if we are on the expiration path of the in-service queue ++ * ++ * This function is invoked when there has been a change in the trees ++ * for sd, and we need to know what is the new next entity to serve ++ * after this change. ++ */ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ bool expiration) ++{ ++ struct bfq_service_tree *st = sd->service_tree; ++ struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1); ++ struct bfq_entity *entity = NULL; ++ struct bfq_queue *bfqq; ++ int class_idx = 0; ++ ++ BUG_ON(!sd); ++ BUG_ON(!st); ++ /* ++ * Choose from idle class, if needed to guarantee a minimum ++ * bandwidth to this class (and if there is some active entity ++ * in idle class). This should also mitigate ++ * priority-inversion problems in case a low priority task is ++ * holding file system resources. ++ */ ++ if (time_is_before_jiffies(sd->bfq_class_idle_last_service + ++ BFQ_CL_IDLE_TIMEOUT)) { ++ if (!RB_EMPTY_ROOT(&idle_class_st->active)) ++ class_idx = BFQ_IOPRIO_CLASSES - 1; ++ /* About to be served if backlogged, or not yet backlogged */ ++ sd->bfq_class_idle_last_service = jiffies; ++ } ++ ++ /* ++ * Find the next entity to serve for the highest-priority ++ * class, unless the idle class needs to be served. ++ */ ++ for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) { ++ /* ++ * If expiration is true, then bfq_lookup_next_entity ++ * is being invoked as a part of the expiration path ++ * of the in-service queue. In this case, even if ++ * sd->in_service_entity is not NULL, ++ * sd->in_service_entiy at this point is actually not ++ * in service any more, and, if needed, has already ++ * been properly queued or requeued into the right ++ * tree. The reason why sd->in_service_entity is still ++ * not NULL here, even if expiration is true, is that ++ * sd->in_service_entiy is reset as a last step in the ++ * expiration path. So, if expiration is true, tell ++ * __bfq_lookup_next_entity that there is no ++ * sd->in_service_entity. ++ */ ++ entity = __bfq_lookup_next_entity(st + class_idx, ++ sd->in_service_entity && ++ !expiration); ++ ++ if (entity) ++ break; ++ } ++ ++ BUG_ON(!entity && ++ (!RB_EMPTY_ROOT(&st->active) || !RB_EMPTY_ROOT(&(st+1)->active) || ++ !RB_EMPTY_ROOT(&(st+2)->active))); ++ ++ if (!entity) ++ return NULL; ++ ++ /* Log some information */ ++ bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "chosen from st %p %d", ++ st + class_idx, class_idx); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "chosen from st %p %d", ++ st + class_idx, class_idx); ++ } ++#endif ++ ++ return entity; ++} ++ ++static bool next_queue_may_preempt(struct bfq_data *bfqd) ++{ ++ struct bfq_sched_data *sd = &bfqd->root_group->sched_data; ++ ++ return sd->next_in_service != sd->in_service_entity; ++} ++ ++/* ++ * Get next queue for service. ++ */ ++static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_entity *entity = NULL; ++ struct bfq_sched_data *sd; ++ struct bfq_queue *bfqq; ++ ++ BUG_ON(bfqd->in_service_queue); ++ ++ if (bfq_tot_busy_queues(bfqd) == 0) ++ return NULL; ++ ++ /* ++ * Traverse the path from the root to the leaf entity to ++ * serve. Set in service all the entities visited along the ++ * way. ++ */ ++ sd = &bfqd->root_group->sched_data; ++ for (; sd ; sd = entity->my_sched_data) { ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ if (entity) { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "lookup in this group"); ++ if (!sd->next_in_service) ++ pr_crit("lookup in this group"); ++ } else { ++ bfq_log_bfqg(bfqd, bfqd->root_group, ++ "lookup in root group"); ++ if (!sd->next_in_service) ++ pr_crit("lookup in root group"); ++ } ++#endif ++ ++ BUG_ON(!sd->next_in_service); ++ ++ /* ++ * WARNING. We are about to set the in-service entity ++ * to sd->next_in_service, i.e., to the (cached) value ++ * returned by bfq_lookup_next_entity(sd) the last ++ * time it was invoked, i.e., the last time when the ++ * service order in sd changed as a consequence of the ++ * activation or deactivation of an entity. In this ++ * respect, if we execute bfq_lookup_next_entity(sd) ++ * in this very moment, it may, although with low ++ * probability, yield a different entity than that ++ * pointed to by sd->next_in_service. This rare event ++ * happens in case there was no CLASS_IDLE entity to ++ * serve for sd when bfq_lookup_next_entity(sd) was ++ * invoked for the last time, while there is now one ++ * such entity. ++ * ++ * If the above event happens, then the scheduling of ++ * such entity in CLASS_IDLE is postponed until the ++ * service of the sd->next_in_service entity ++ * finishes. In fact, when the latter is expired, ++ * bfq_lookup_next_entity(sd) gets called again, ++ * exactly to update sd->next_in_service. ++ */ ++ ++ /* Make next_in_service entity become in_service_entity */ ++ entity = sd->next_in_service; ++ sd->in_service_entity = entity; ++ ++ /* ++ * If entity is no longer a candidate for next ++ * service, then it must be extracted from its active ++ * tree, so as to make sure that it won't be ++ * considered when computing next_in_service. See the ++ * comments on the function ++ * bfq_no_longer_next_in_service() for details. ++ */ ++ if (bfq_no_longer_next_in_service(entity)) ++ bfq_active_extract(bfq_entity_service_tree(entity), ++ entity); ++ ++ /* ++ * Even if entity is not to be extracted according to ++ * the above check, a descendant entity may get ++ * extracted in one of the next iterations of this ++ * loop. Such an event could cause a change in ++ * next_in_service for the level of the descendant ++ * entity, and thus possibly back to this level. ++ * ++ * However, we cannot perform the resulting needed ++ * update of next_in_service for this level before the ++ * end of the whole loop, because, to know which is ++ * the correct next-to-serve candidate entity for each ++ * level, we need first to find the leaf entity to set ++ * in service. In fact, only after we know which is ++ * the next-to-serve leaf entity, we can discover ++ * whether the parent entity of the leaf entity ++ * becomes the next-to-serve, and so on. ++ */ ++ ++ /* Log some information */ ++ bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "this queue, finish %llu", ++ (((entity->finish>>10)*1000)>>10)>>2); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "this entity, finish %llu", ++ (((entity->finish>>10)*1000)>>10)>>2); ++ } ++#endif ++ ++ } ++ ++ BUG_ON(!entity); ++ bfqq = bfq_entity_to_bfqq(entity); ++ BUG_ON(!bfqq); ++ ++ /* ++ * We can finally update all next-to-serve entities along the ++ * path from the leaf entity just set in service to the root. ++ */ ++ for_each_entity(entity) { ++ struct bfq_sched_data *sd = entity->sched_data; ++ ++ if (!bfq_update_next_in_service(sd, NULL, false)) ++ break; ++ } ++ ++ return bfqq; ++} ++ ++static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue; ++ struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity; ++ struct bfq_entity *entity = in_serv_entity; ++ ++#ifndef BFQ_MQ ++ if (bfqd->in_service_bic) { ++ put_io_context(bfqd->in_service_bic->icq.ioc); ++ bfqd->in_service_bic = NULL; ++ } ++#endif ++ ++ bfq_clear_bfqq_wait_request(in_serv_bfqq); ++ hrtimer_try_to_cancel(&bfqd->idle_slice_timer); ++ bfqd->in_service_queue = NULL; ++ ++ /* ++ * When this function is called, all in-service entities have ++ * been properly deactivated or requeued, so we can safely ++ * execute the final step: reset in_service_entity along the ++ * path from entity to the root. ++ */ ++ for_each_entity(entity) ++ entity->sched_data->in_service_entity = NULL; ++ ++ /* ++ * in_serv_entity is no longer in service, so, if it is in no ++ * service tree either, then release the service reference to ++ * the queue it represents (taken with bfq_get_entity). ++ */ ++ if (!in_serv_entity->on_st) ++ bfq_put_queue(in_serv_bfqq); ++} ++ ++static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool ins_into_idle_tree, bool expiration) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_deactivate_entity(entity, ins_into_idle_tree, expiration); ++} ++ ++static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ BUG_ON(entity->tree != &st->active && entity->tree != &st->idle && ++ entity->on_st); ++ ++ bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq), ++ false, false); ++ bfq_clear_bfqq_non_blocking_wait_rq(bfqq); ++} ++ ++static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool expiration) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_activate_requeue_entity(entity, false, ++ bfqq == bfqd->in_service_queue, expiration); ++} ++ ++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg); ++ ++/* ++ * Called when the bfqq no longer has requests pending, remove it from ++ * the service tree. As a special case, it can be invoked during an ++ * expiration. ++ */ ++static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool expiration) ++{ ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ bfq_log_bfqq(bfqd, bfqq, "del from busy"); ++ ++ bfq_clear_bfqq_busy(bfqq); ++ ++ BUG_ON(bfq_tot_busy_queues(bfqd) == 0); ++ bfqd->busy_queues[bfqq->ioprio_class - 1]--; ++ ++ if (bfqq->wr_coeff > 1) { ++ bfqd->wr_busy_queues--; ++ BUG_ON(bfqd->wr_busy_queues < 0); ++ } ++ ++ bfqg_stats_update_dequeue(bfqq_group(bfqq)); ++ ++ BUG_ON(bfqq->entity.budget < 0); ++ ++ bfq_deactivate_bfqq(bfqd, bfqq, true, expiration); ++ if (!bfqq->dispatched) ++ bfq_weights_tree_remove(bfqd, bfqq); ++} ++ ++/* ++ * Called when an inactive queue receives a new request. ++ */ ++static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ ++ bfq_log_bfqq(bfqd, bfqq, "add to busy"); ++ ++ bfq_activate_bfqq(bfqd, bfqq); ++ ++ bfq_mark_bfqq_busy(bfqq); ++ bfqd->busy_queues[bfqq->ioprio_class - 1]++; ++ ++ if (!bfqq->dispatched) ++ if (bfqq->wr_coeff == 1) ++ bfq_weights_tree_add(bfqd, bfqq, ++ &bfqd->queue_weights_tree); ++ ++ if (bfqq->wr_coeff > 1) { ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd)); ++ } ++ ++} +diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c +new file mode 100644 +index 000000000000..6da94eef0cf1 +--- /dev/null ++++ b/block/bfq-sq-iosched.c +@@ -0,0 +1,5957 @@ ++/* ++ * Budget Fair Queueing (BFQ) I/O scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org> ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ * ++ * BFQ is a proportional-share I/O scheduler, with some extra ++ * low-latency capabilities. BFQ also supports full hierarchical ++ * scheduling through cgroups. Next paragraphs provide an introduction ++ * on BFQ inner workings. Details on BFQ benefits and usage can be ++ * found in Documentation/block/bfq-iosched.txt. ++ * ++ * BFQ is a proportional-share storage-I/O scheduling algorithm based ++ * on the slice-by-slice service scheme of CFQ. But BFQ assigns ++ * budgets, measured in number of sectors, to processes instead of ++ * time slices. The device is not granted to the in-service process ++ * for a given time slice, but until it has exhausted its assigned ++ * budget. This change from the time to the service domain enables BFQ ++ * to distribute the device throughput among processes as desired, ++ * without any distortion due to throughput fluctuations, or to device ++ * internal queueing. BFQ uses an ad hoc internal scheduler, called ++ * B-WF2Q+, to schedule processes according to their budgets. More ++ * precisely, BFQ schedules queues associated with processes. Thanks to ++ * the accurate policy of B-WF2Q+, BFQ can afford to assign high ++ * budgets to I/O-bound processes issuing sequential requests (to ++ * boost the throughput), and yet guarantee a low latency to ++ * interactive and soft real-time applications. ++ * ++ * In particular, BFQ schedules I/O so as to achieve the latter goal-- ++ * low latency for interactive and soft real-time applications--if the ++ * low_latency parameter is set (default configuration). To this ++ * purpose, BFQ constantly tries to detect whether the I/O requests in ++ * a bfq_queue come from an interactive or a soft real-time ++ * application. For brevity, in these cases, the queue is said to be ++ * interactive or soft real-time. In both cases, BFQ privileges the ++ * service of the queue, over that of non-interactive and ++ * non-soft-real-time queues. This privileging is performed, mainly, ++ * by raising the weight of the queue. So, for brevity, we call just ++ * weight-raising periods the time periods during which a queue is ++ * privileged, because deemed interactive or soft real-time. ++ * ++ * The detection of soft real-time queues/applications is described in ++ * detail in the comments on the function ++ * bfq_bfqq_softrt_next_start. On the other hand, the detection of an ++ * interactive queue works as follows: a queue is deemed interactive ++ * if it is constantly non empty only for a limited time interval, ++ * after which it does become empty. The queue may be deemed ++ * interactive again (for a limited time), if it restarts being ++ * constantly non empty, provided that this happens only after the ++ * queue has remained empty for a given minimum idle time. ++ * ++ * By default, BFQ computes automatically the above maximum time ++ * interval, i.e., the time interval after which a constantly ++ * non-empty queue stops being deemed interactive. Since a queue is ++ * weight-raised while it is deemed interactive, this maximum time ++ * interval happens to coincide with the (maximum) duration of the ++ * weight-raising for interactive queues. ++ * ++ * NOTE: if the main or only goal, with a given device, is to achieve ++ * the maximum-possible throughput at all times, then do switch off ++ * all low-latency heuristics for that device, by setting low_latency ++ * to 0. ++ * ++ * BFQ is described in [1], where also a reference to the initial, ++ * more theoretical paper on BFQ can be found. The interested reader ++ * can find in the latter paper full details on the main algorithm, as ++ * well as formulas of the guarantees and formal proofs of all the ++ * properties. With respect to the version of BFQ presented in these ++ * papers, this implementation adds a few more heuristics, such as the ++ * one that guarantees a low latency to soft real-time applications, ++ * and a hierarchical extension based on H-WF2Q+. ++ * ++ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with ++ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N) ++ * complexity derives from the one introduced with EEVDF in [3]. ++ * ++ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O ++ * Scheduler", Proceedings of the First Workshop on Mobile System ++ * Technologies (MST-2015), May 2015. ++ * http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf ++ * ++ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf ++ * ++ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing ++ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689, ++ * Oct 1997. ++ * ++ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz ++ * ++ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline ++ * First: A Flexible and Accurate Mechanism for Proportional Share ++ * Resource Allocation,'' technical report. ++ * ++ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf ++ */ ++#include <linux/module.h> ++#include <linux/slab.h> ++#include <linux/blkdev.h> ++#include <linux/cgroup.h> ++#include <linux/elevator.h> ++#include <linux/jiffies.h> ++#include <linux/rbtree.h> ++#include <linux/ioprio.h> ++#include "blk.h" ++#include "bfq.h" ++#include "blk-wbt.h" ++ ++/* Expiration time of sync (0) and async (1) requests, in ns. */ ++static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 }; ++ ++/* Maximum backwards seek, in KiB. */ ++static const int bfq_back_max = (16 * 1024); ++ ++/* Penalty of a backwards seek, in number of sectors. */ ++static const int bfq_back_penalty = 2; ++ ++/* Idling period duration, in ns. */ ++static u32 bfq_slice_idle = (NSEC_PER_SEC / 125); ++ ++/* Minimum number of assigned budgets for which stats are safe to compute. */ ++static const int bfq_stats_min_budgets = 194; ++ ++/* Default maximum budget values, in sectors and number of requests. */ ++static const int bfq_default_max_budget = (16 * 1024); ++ ++/* ++ * When a sync request is dispatched, the queue that contains that ++ * request, and all the ancestor entities of that queue, are charged ++ * with the number of sectors of the request. In constrast, if the ++ * request is async, then the queue and its ancestor entities are ++ * charged with the number of sectors of the request, multiplied by ++ * the factor below. This throttles the bandwidth for async I/O, ++ * w.r.t. to sync I/O, and it is done to counter the tendency of async ++ * writes to steal I/O throughput to reads. ++ * ++ * The current value of this parameter is the result of a tuning with ++ * several hardware and software configurations. We tried to find the ++ * lowest value for which writes do not cause noticeable problems to ++ * reads. In fact, the lower this parameter, the stabler I/O control, ++ * in the following respect. The lower this parameter is, the less ++ * the bandwidth enjoyed by a group decreases ++ * - when the group does writes, w.r.t. to when it does reads; ++ * - when other groups do reads, w.r.t. to when they do writes. ++ */ ++static const int bfq_async_charge_factor = 3; ++ ++/* Default timeout values, in jiffies, approximating CFQ defaults. */ ++static const int bfq_timeout = (HZ / 8); ++ ++/* ++ * Time limit for merging (see comments in bfq_setup_cooperator). Set ++ * to the slowest value that, in our tests, proved to be effective in ++ * removing false positives, while not causing true positives to miss ++ * queue merging. ++ * ++ * As can be deduced from the low time limit below, queue merging, if ++ * successful, happens at the very beggining of the I/O of the involved ++ * cooperating processes, as a consequence of the arrival of the very ++ * first requests from each cooperator. After that, there is very ++ * little chance to find cooperators. ++ */ ++static const unsigned long bfq_merge_time_limit = HZ/10; ++ ++#define MAX_LENGTH_REASON_NAME 25 ++ ++static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE", ++"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS", ++"PREEMPTED"}; ++ ++static struct kmem_cache *bfq_pool; ++ ++/* Below this threshold (in ns), we consider thinktime immediate. */ ++#define BFQ_MIN_TT (2 * NSEC_PER_MSEC) ++ ++/* hw_tag detection: parallel requests threshold and min samples needed. */ ++#define BFQ_HW_QUEUE_THRESHOLD 3 ++#define BFQ_HW_QUEUE_SAMPLES 32 ++ ++#define BFQQ_SEEK_THR (sector_t)(8 * 100) ++#define BFQQ_SECT_THR_NONROT (sector_t)(2 * 32) ++#define BFQ_RQ_SEEKY(bfqd, last_pos, rq) \ ++ (get_sdist(last_pos, rq) > \ ++ BFQQ_SEEK_THR && \ ++ (!blk_queue_nonrot(bfqd->queue) || \ ++ blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT)) ++#define BFQQ_CLOSE_THR (sector_t)(8 * 1024) ++#define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 19) ++ ++/* Min number of samples required to perform peak-rate update */ ++#define BFQ_RATE_MIN_SAMPLES 32 ++/* Min observation time interval required to perform a peak-rate update (ns) */ ++#define BFQ_RATE_MIN_INTERVAL (300*NSEC_PER_MSEC) ++/* Target observation time interval for a peak-rate update (ns) */ ++#define BFQ_RATE_REF_INTERVAL NSEC_PER_SEC ++ ++/* ++ * Shift used for peak-rate fixed precision calculations. ++ * With ++ * - the current shift: 16 positions ++ * - the current type used to store rate: u32 ++ * - the current unit of measure for rate: [sectors/usec], or, more precisely, ++ * [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift, ++ * the range of rates that can be stored is ++ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec = ++ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec = ++ * [15, 65G] sectors/sec ++ * Which, assuming a sector size of 512B, corresponds to a range of ++ * [7.5K, 33T] B/sec ++ */ ++#define BFQ_RATE_SHIFT 16 ++ ++/* ++ * When configured for computing the duration of the weight-raising ++ * for interactive queues automatically (see the comments at the ++ * beginning of this file), BFQ does it using the following formula: ++ * duration = (ref_rate / r) * ref_wr_duration, ++ * where r is the peak rate of the device, and ref_rate and ++ * ref_wr_duration are two reference parameters. In particular, ++ * ref_rate is the peak rate of the reference storage device (see ++ * below), and ref_wr_duration is about the maximum time needed, with ++ * BFQ and while reading two files in parallel, to load typical large ++ * applications on the reference device (see the comments on ++ * max_service_from_wr below, for more details on how ref_wr_duration ++ * is obtained). In practice, the slower/faster the device at hand ++ * is, the more/less it takes to load applications with respect to the ++ * reference device. Accordingly, the longer/shorter BFQ grants ++ * weight raising to interactive applications. ++ * ++ * BFQ uses two different reference pairs (ref_rate, ref_wr_duration), ++ * depending on whether the device is rotational or non-rotational. ++ * ++ * In the following definitions, ref_rate[0] and ref_wr_duration[0] ++ * are the reference values for a rotational device, whereas ++ * ref_rate[1] and ref_wr_duration[1] are the reference values for a ++ * non-rotational device. The reference rates are not the actual peak ++ * rates of the devices used as a reference, but slightly lower ++ * values. The reason for using slightly lower values is that the ++ * peak-rate estimator tends to yield slightly lower values than the ++ * actual peak rate (it can yield the actual peak rate only if there ++ * is only one process doing I/O, and the process does sequential ++ * I/O). ++ * ++ * The reference peak rates are measured in sectors/usec, left-shifted ++ * by BFQ_RATE_SHIFT. ++ */ ++static int ref_rate[2] = {14000, 33000}; ++/* ++ * To improve readability, a conversion function is used to initialize ++ * the following array, which entails that the array can be ++ * initialized only in a function. ++ */ ++static int ref_wr_duration[2]; ++ ++/* ++ * BFQ uses the above-detailed, time-based weight-raising mechanism to ++ * privilege interactive tasks. This mechanism is vulnerable to the ++ * following false positives: I/O-bound applications that will go on ++ * doing I/O for much longer than the duration of weight ++ * raising. These applications have basically no benefit from being ++ * weight-raised at the beginning of their I/O. On the opposite end, ++ * while being weight-raised, these applications ++ * a) unjustly steal throughput to applications that may actually need ++ * low latency; ++ * b) make BFQ uselessly perform device idling; device idling results ++ * in loss of device throughput with most flash-based storage, and may ++ * increase latencies when used purposelessly. ++ * ++ * BFQ tries to reduce these problems, by adopting the following ++ * countermeasure. To introduce this countermeasure, we need first to ++ * finish explaining how the duration of weight-raising for ++ * interactive tasks is computed. ++ * ++ * For a bfq_queue deemed as interactive, the duration of weight ++ * raising is dynamically adjusted, as a function of the estimated ++ * peak rate of the device, so as to be equal to the time needed to ++ * execute the 'largest' interactive task we benchmarked so far. By ++ * largest task, we mean the task for which each involved process has ++ * to do more I/O than for any of the other tasks we benchmarked. This ++ * reference interactive task is the start-up of LibreOffice Writer, ++ * and in this task each process/bfq_queue needs to have at most ~110K ++ * sectors transfered. ++ * ++ * This last piece of information enables BFQ to reduce the actual ++ * duration of weight-raising for at least one class of I/O-bound ++ * applications: those doing sequential or quasi-sequential I/O. An ++ * example is file copy. In fact, once started, the main I/O-bound ++ * processes of these applications usually consume the above 110K ++ * sectors in much less time than the processes of an application that ++ * is starting, because these I/O-bound processes will greedily devote ++ * almost all their CPU cycles only to their target, ++ * throughput-friendly I/O operations. This is even more true if BFQ ++ * happens to be underestimating the device peak rate, and thus ++ * overestimating the duration of weight raising. But, according to ++ * our measurements, once transferred 110K sectors, these processes ++ * have no right to be weight-raised any longer. ++ * ++ * Basing on the last consideration, BFQ ends weight-raising for a ++ * bfq_queue if the latter happens to have received an amount of ++ * service at least equal to the following constant. The constant is ++ * set to slightly more than 110K, to have a minimum safety margin. ++ * ++ * This early ending of weight-raising reduces the amount of time ++ * during which interactive false positives cause the two problems ++ * described at the beginning of these comments. ++ */ ++static const unsigned long max_service_from_wr = 120000; ++ ++#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ ++ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) ++ ++#define RQ_BIC(rq) icq_to_bic((rq)->elv.priv[0]) ++#define RQ_BFQQ(rq) ((rq)->elv.priv[1]) ++ ++static void bfq_schedule_dispatch(struct bfq_data *bfqd); ++ ++#include "bfq-ioc.c" ++#include "bfq-sched.c" ++#include "bfq-cgroup-included.c" ++ ++#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) ++#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) ++ ++#define bfq_sample_valid(samples) ((samples) > 80) ++ ++/* ++ * Scheduler run of queue, if there are requests pending and no one in the ++ * driver that will restart queueing. ++ */ ++static void bfq_schedule_dispatch(struct bfq_data *bfqd) ++{ ++ if (bfqd->queued != 0) { ++ bfq_log(bfqd, ""); ++ kblockd_schedule_work(&bfqd->unplug_work); ++ } ++} ++ ++/* ++ * Lifted from AS - choose which of rq1 and rq2 that is best served now. ++ * We choose the request that is closesr to the head right now. Distance ++ * behind the head is penalized and only allowed to a certain extent. ++ */ ++static struct request *bfq_choose_req(struct bfq_data *bfqd, ++ struct request *rq1, ++ struct request *rq2, ++ sector_t last) ++{ ++ sector_t s1, s2, d1 = 0, d2 = 0; ++ unsigned long back_max; ++#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */ ++#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ ++ unsigned int wrap = 0; /* bit mask: requests behind the disk head? */ ++ ++ if (!rq1 || rq1 == rq2) ++ return rq2; ++ if (!rq2) ++ return rq1; ++ ++ if (rq_is_sync(rq1) && !rq_is_sync(rq2)) ++ return rq1; ++ else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) ++ return rq2; ++ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) ++ return rq1; ++ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META)) ++ return rq2; ++ ++ s1 = blk_rq_pos(rq1); ++ s2 = blk_rq_pos(rq2); ++ ++ /* ++ * By definition, 1KiB is 2 sectors. ++ */ ++ back_max = bfqd->bfq_back_max * 2; ++ ++ /* ++ * Strict one way elevator _except_ in the case where we allow ++ * short backward seeks which are biased as twice the cost of a ++ * similar forward seek. ++ */ ++ if (s1 >= last) ++ d1 = s1 - last; ++ else if (s1 + back_max >= last) ++ d1 = (last - s1) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ1_WRAP; ++ ++ if (s2 >= last) ++ d2 = s2 - last; ++ else if (s2 + back_max >= last) ++ d2 = (last - s2) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ2_WRAP; ++ ++ /* Found required data */ ++ ++ /* ++ * By doing switch() on the bit mask "wrap" we avoid having to ++ * check two variables for all permutations: --> faster! ++ */ ++ switch (wrap) { ++ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ ++ if (d1 < d2) ++ return rq1; ++ else if (d2 < d1) ++ return rq2; ++ ++ if (s1 >= s2) ++ return rq1; ++ else ++ return rq2; ++ ++ case BFQ_RQ2_WRAP: ++ return rq1; ++ case BFQ_RQ1_WRAP: ++ return rq2; ++ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */ ++ default: ++ /* ++ * Since both rqs are wrapped, ++ * start with the one that's further behind head ++ * (--> only *one* back seek required), ++ * since back seek takes more time than forward. ++ */ ++ if (s1 <= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++} ++ ++static struct bfq_queue * ++bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, ++ sector_t sector, struct rb_node **ret_parent, ++ struct rb_node ***rb_link) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *bfqq = NULL; ++ ++ parent = NULL; ++ p = &root->rb_node; ++ while (*p) { ++ struct rb_node **n; ++ ++ parent = *p; ++ bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ ++ /* ++ * Sort strictly based on sector. Smallest to the left, ++ * largest to the right. ++ */ ++ if (sector > blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_right; ++ else if (sector < blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_left; ++ else ++ break; ++ p = n; ++ bfqq = NULL; ++ } ++ ++ *ret_parent = parent; ++ if (rb_link) ++ *rb_link = p; ++ ++ bfq_log(bfqd, "%llu: returning %d", ++ (unsigned long long) sector, ++ bfqq ? bfqq->pid : 0); ++ ++ return bfqq; ++} ++ ++static bool bfq_too_late_for_merging(struct bfq_queue *bfqq) ++{ ++ return bfqq->service_from_backlogged > 0 && ++ time_is_before_jiffies(bfqq->first_IO_time + ++ bfq_merge_time_limit); ++} ++ ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *__bfqq; ++ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ ++ /* ++ * bfqq cannot be merged any longer (see comments in ++ * bfq_setup_cooperator): no point in adding bfqq into the ++ * position tree. ++ */ ++ if (bfq_too_late_for_merging(bfqq)) ++ return; ++ ++ if (bfq_class_idle(bfqq)) ++ return; ++ if (!bfqq->next_rq) ++ return; ++ ++ bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root, ++ blk_rq_pos(bfqq->next_rq), &parent, &p); ++ if (!__bfqq) { ++ rb_link_node(&bfqq->pos_node, parent, p); ++ rb_insert_color(&bfqq->pos_node, bfqq->pos_root); ++ } else ++ bfqq->pos_root = NULL; ++} ++ ++/* ++ * The following function returns true if every queue must receive the ++ * same share of the throughput (this condition is used when deciding ++ * whether idling may be disabled, see the comments in the function ++ * bfq_better_to_idle()). ++ * ++ * Such a scenario occurs when: ++ * 1) all active queues have the same weight, ++ * 2) all active queues belong to the same I/O-priority class, ++ * 3) all active groups at the same level in the groups tree have the same ++ * weight, ++ * 4) all active groups at the same level in the groups tree have the same ++ * number of children. ++ * ++ * Unfortunately, keeping the necessary state for evaluating exactly ++ * the last two symmetry sub-conditions above would be quite complex ++ * and time consuming. Therefore this function evaluates, instead, ++ * only the following stronger three sub-conditions, for which it is ++ * much easier to maintain the needed state: ++ * 1) all active queues have the same weight, ++ * 2) all active queues belong to the same I/O-priority class, ++ * 3) there are no active groups. ++ * In particular, the last condition is always true if hierarchical ++ * support or the cgroups interface are not enabled, thus no state ++ * needs to be maintained in this case. ++ */ ++static bool bfq_symmetric_scenario(struct bfq_data *bfqd) ++{ ++ /* ++ * For queue weights to differ, queue_weights_tree must contain ++ * at least two nodes. ++ */ ++ bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && ++ (bfqd->queue_weights_tree.rb_node->rb_left || ++ bfqd->queue_weights_tree.rb_node->rb_right); ++ ++ bool multiple_classes_busy = ++ (bfqd->busy_queues[0] && bfqd->busy_queues[1]) || ++ (bfqd->busy_queues[0] && bfqd->busy_queues[2]) || ++ (bfqd->busy_queues[1] && bfqd->busy_queues[2]); ++ ++ bfq_log(bfqd, "varied_queue_weights %d mul_classes %d", ++ varied_queue_weights, multiple_classes_busy); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ bfq_log(bfqd, "num_groups_with_pending_reqs %u", ++ bfqd->num_groups_with_pending_reqs); ++#endif ++ ++ return !(varied_queue_weights || multiple_classes_busy ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ || bfqd->num_groups_with_pending_reqs > 0 ++#endif ++ ); ++} ++ ++/* ++ * If the weight-counter tree passed as input contains no counter for ++ * the weight of the input queue, then add that counter; otherwise just ++ * increment the existing counter. ++ * ++ * Note that weight-counter trees contain few nodes in mostly symmetric ++ * scenarios. For example, if all queues have the same weight, then the ++ * weight-counter tree for the queues may contain at most one node. ++ * This holds even if low_latency is on, because weight-raised queues ++ * are not inserted in the tree. ++ * In most scenarios, the rate at which nodes are created/destroyed ++ * should be low too. ++ */ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct rb_node **new = &(root->rb_node), *parent = NULL; ++ ++ /* ++ * Do not insert if the queue is already associated with a ++ * counter, which happens if: ++ * 1) a request arrival has caused the queue to become both ++ * non-weight-raised, and hence change its weight, and ++ * backlogged; in this respect, each of the two events ++ * causes an invocation of this function, ++ * 2) this is the invocation of this function caused by the ++ * second event. This second invocation is actually useless, ++ * and we handle this fact by exiting immediately. More ++ * efficient or clearer solutions might possibly be adopted. ++ */ ++ if (bfqq->weight_counter) ++ return; ++ ++ while (*new) { ++ struct bfq_weight_counter *__counter = container_of(*new, ++ struct bfq_weight_counter, ++ weights_node); ++ parent = *new; ++ ++ if (entity->weight == __counter->weight) { ++ bfqq->weight_counter = __counter; ++ goto inc_counter; ++ } ++ if (entity->weight < __counter->weight) ++ new = &((*new)->rb_left); ++ else ++ new = &((*new)->rb_right); ++ } ++ ++ bfqq->weight_counter = kzalloc(sizeof(struct bfq_weight_counter), ++ GFP_ATOMIC); ++ ++ /* ++ * In the unlucky event of an allocation failure, we just ++ * exit. This will cause the weight of queue to not be ++ * considered in bfq_symmetric_scenario, which, in its turn, ++ * causes the scenario to be deemed wrongly symmetric in case ++ * bfqq's weight would have been the only weight making the ++ * scenario asymmetric. On the bright side, no unbalance will ++ * however occur when bfqq becomes inactive again (the ++ * invocation of this function is triggered by an activation ++ * of queue). In fact, bfq_weights_tree_remove does nothing ++ * if !bfqq->weight_counter. ++ */ ++ if (unlikely(!bfqq->weight_counter)) ++ return; ++ ++ bfqq->weight_counter->weight = entity->weight; ++ rb_link_node(&bfqq->weight_counter->weights_node, parent, new); ++ rb_insert_color(&bfqq->weight_counter->weights_node, root); ++ ++inc_counter: ++ bfqq->weight_counter->num_active++; ++ bfqq->ref++; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "refs %d weight %d symmetric %d", ++ bfqq->ref, ++ entity->weight, ++ bfq_symmetric_scenario(bfqd)); ++} ++ ++/* ++ * Decrement the weight counter associated with the queue, and, if the ++ * counter reaches 0, remove the counter from the tree. ++ * See the comments to the function bfq_weights_tree_add() for considerations ++ * about overhead. ++ */ ++static void __bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct rb_root *root) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (!bfqq->weight_counter) ++ return; ++ ++ BUG_ON(RB_EMPTY_ROOT(root)); ++ BUG_ON(bfqq->weight_counter->weight != entity->weight); ++ ++ BUG_ON(!bfqq->weight_counter->num_active); ++ bfqq->weight_counter->num_active--; ++ ++ if (bfqq->weight_counter->num_active > 0) ++ goto reset_entity_pointer; ++ ++ rb_erase(&bfqq->weight_counter->weights_node, root); ++ kfree(bfqq->weight_counter); ++ ++reset_entity_pointer: ++ bfqq->weight_counter = NULL; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "refs %d weight %d symmetric %d", ++ bfqq->ref, ++ entity->weight, ++ bfq_symmetric_scenario(bfqd)); ++ bfq_put_queue(bfqq); ++} ++ ++/* ++ * Invoke __bfq_weights_tree_remove on bfqq and decrement the number ++ * of active groups for each queue's inactive parent entity. ++ */ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = bfqq->entity.parent; ++ ++ for_each_entity(entity) { ++ struct bfq_sched_data *sd = entity->my_sched_data; ++ ++ BUG_ON(entity->sched_data == NULL); /* ++ * It would mean ++ * that this is ++ * the root group. ++ */ ++ ++ if (sd->next_in_service || sd->in_service_entity) { ++ BUG_ON(!entity->in_groups_with_pending_reqs); ++ /* ++ * entity is still active, because either ++ * next_in_service or in_service_entity is not ++ * NULL (see the comments on the definition of ++ * next_in_service for details on why ++ * in_service_entity must be checked too). ++ * ++ * As a consequence, its parent entities are ++ * active as well, and thus this loop must ++ * stop here. ++ */ ++ break; ++ } ++ ++ BUG_ON(!bfqd->num_groups_with_pending_reqs && ++ entity->in_groups_with_pending_reqs); ++ /* ++ * The decrement of num_groups_with_pending_reqs is ++ * not performed immediately upon the deactivation of ++ * entity, but it is delayed to when it also happens ++ * that the first leaf descendant bfqq of entity gets ++ * all its pending requests completed. The following ++ * instructions perform this delayed decrement, if ++ * needed. See the comments on ++ * num_groups_with_pending_reqs for details. ++ */ ++ if (entity->in_groups_with_pending_reqs) { ++ entity->in_groups_with_pending_reqs = false; ++ bfqd->num_groups_with_pending_reqs--; ++ } ++ bfq_log_bfqq(bfqd, bfqq, "num_groups_with_pending_reqs %u", ++ bfqd->num_groups_with_pending_reqs); ++ } ++ ++ /* ++ * Next function is invoked last, because it causes bfqq to be ++ * freed if the following holds: bfqq is not in service and ++ * has no dispatched request. DO NOT use bfqq after the next ++ * function invocation. ++ */ ++ __bfq_weights_tree_remove(bfqd, bfqq, ++ &bfqd->queue_weights_tree); ++} ++ ++/* ++ * Return expired entry, or NULL to just start from scratch in rbtree. ++ */ ++static struct request *bfq_check_fifo(struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct request *rq; ++ ++ if (bfq_bfqq_fifo_expire(bfqq)) ++ return NULL; ++ ++ bfq_mark_bfqq_fifo_expire(bfqq); ++ ++ rq = rq_entry_fifo(bfqq->fifo.next); ++ ++ if (rq == last || ktime_get_ns() < rq->fifo_time) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq); ++ BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); ++ return rq; ++} ++ ++static struct request *bfq_find_next_rq(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct rb_node *rbnext = rb_next(&last->rb_node); ++ struct rb_node *rbprev = rb_prev(&last->rb_node); ++ struct request *next, *prev = NULL; ++ ++ BUG_ON(list_empty(&bfqq->fifo)); ++ ++ /* Follow expired path, else get first next available. */ ++ next = bfq_check_fifo(bfqq, last); ++ if (next) { ++ BUG_ON(next == last); ++ return next; ++ } ++ ++ BUG_ON(RB_EMPTY_NODE(&last->rb_node)); ++ ++ if (rbprev) ++ prev = rb_entry_rq(rbprev); ++ ++ if (rbnext) ++ next = rb_entry_rq(rbnext); ++ else { ++ rbnext = rb_first(&bfqq->sort_list); ++ if (rbnext && rbnext != &last->rb_node) ++ next = rb_entry_rq(rbnext); ++ } ++ ++ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last)); ++} ++ ++/* see the definition of bfq_async_charge_factor for details */ ++static unsigned long bfq_serv_to_charge(struct request *rq, ++ struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1 || ++ !bfq_symmetric_scenario(bfqq->bfqd)) ++ return blk_rq_sectors(rq); ++ ++ return blk_rq_sectors(rq) * bfq_async_charge_factor; ++} ++ ++/** ++ * bfq_updated_next_req - update the queue after a new next_rq selection. ++ * @bfqd: the device data the queue belongs to. ++ * @bfqq: the queue to update. ++ * ++ * If the first request of a queue changes we make sure that the queue ++ * has enough budget to serve at least its first request (if the ++ * request has grown). We do this because if the queue has not enough ++ * budget for its first request, it has to go through two dispatch ++ * rounds to actually get it dispatched. ++ */ ++static void bfq_updated_next_req(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct request *next_rq = bfqq->next_rq; ++ unsigned long new_budget; ++ ++ if (!next_rq) ++ return; ++ ++ if (bfqq == bfqd->in_service_queue) ++ /* ++ * In order not to break guarantees, budgets cannot be ++ * changed after an entity has been selected. ++ */ ++ return; ++ ++ BUG_ON(entity->tree != &st->active); ++ BUG_ON(entity == entity->sched_data->in_service_entity); ++ ++ new_budget = max_t(unsigned long, ++ max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)), ++ entity->service); ++ if (entity->budget != new_budget) { ++ entity->budget = new_budget; ++ bfq_log_bfqq(bfqd, bfqq, "new budget %lu", ++ new_budget); ++ bfq_requeue_bfqq(bfqd, bfqq, false); ++ } ++} ++ ++static unsigned int bfq_wr_duration(struct bfq_data *bfqd) ++{ ++ u64 dur; ++ ++ if (bfqd->bfq_wr_max_time > 0) ++ return bfqd->bfq_wr_max_time; ++ ++ dur = bfqd->rate_dur_prod; ++ do_div(dur, bfqd->peak_rate); ++ ++ /* ++ * Limit duration between 3 and 25 seconds. The upper limit ++ * has been conservatively set after the following worst case: ++ * on a QEMU/KVM virtual machine ++ * - running in a slow PC ++ * - with a virtual disk stacked on a slow low-end 5400rpm HDD ++ * - serving a heavy I/O workload, such as the sequential reading ++ * of several files ++ * mplayer took 23 seconds to start, if constantly weight-raised. ++ * ++ * As for higher values than that accomodating the above bad ++ * scenario, tests show that higher values would often yield ++ * the opposite of the desired result, i.e., would worsen ++ * responsiveness by allowing non-interactive applications to ++ * preserve weight raising for too long. ++ * ++ * On the other end, lower values than 3 seconds make it ++ * difficult for most interactive tasks to complete their jobs ++ * before weight-raising finishes. ++ */ ++ return clamp_val(dur, msecs_to_jiffies(3000), msecs_to_jiffies(25000)); ++} ++ ++/* switch back from soft real-time to interactive weight raising */ ++static void switch_back_to_interactive_wr(struct bfq_queue *bfqq, ++ struct bfq_data *bfqd) ++{ ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt; ++} ++ ++static void ++bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, bool bfq_already_existing) ++{ ++ unsigned int old_wr_coeff; ++ bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq); ++ ++ if (bic->saved_has_short_ttime) ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ else ++ bfq_clear_bfqq_has_short_ttime(bfqq); ++ ++ if (bic->saved_IO_bound) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ else ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (unlikely(busy)) ++ old_wr_coeff = bfqq->wr_coeff; ++ ++ bfqq->wr_coeff = bic->saved_wr_coeff; ++ bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt; ++ BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt)); ++ bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish; ++ bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time; ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "bic %p wr_coeff %d start_finish %lu max_time %lu", ++ bic, bfqq->wr_coeff, bfqq->last_wr_start_finish, ++ bfqq->wr_cur_max_time); ++ ++ if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) || ++ time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time))) { ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt + ++ bfq_wr_duration(bfqd))) { ++ switch_back_to_interactive_wr(bfqq, bfqd); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "switching back to interactive"); ++ } else { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "switching off wr (%lu + %lu < %lu)", ++ bfqq->last_wr_start_finish, bfqq->wr_cur_max_time, ++ jiffies); ++ } ++ } ++ ++ /* make sure weight will be updated, however we got here */ ++ bfqq->entity.prio_changed = 1; ++ ++ if (likely(!busy)) ++ return; ++ ++ if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) { ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd)); ++ } else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) { ++ bfqd->wr_busy_queues--; ++ BUG_ON(bfqd->wr_busy_queues < 0); ++ } ++} ++ ++static int bfqq_process_refs(struct bfq_queue *bfqq) ++{ ++ int process_refs, io_refs; ++ ++ lockdep_assert_held(bfqq->bfqd->queue->queue_lock); ++ ++ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; ++ process_refs = bfqq->ref - io_refs - bfqq->entity.on_st - ++ (bfqq->weight_counter != NULL); ++ BUG_ON(process_refs < 0); ++ return process_refs; ++} ++ ++/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ ++static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *item; ++ struct hlist_node *n; ++ ++ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node) ++ hlist_del_init(&item->burst_list_node); ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++ bfqd->burst_size = 1; ++ bfqd->burst_parent_entity = bfqq->entity.parent; ++} ++ ++/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */ ++static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* Increment burst size to take into account also bfqq */ ++ bfqd->burst_size++; ++ ++ bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size); ++ ++ BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh); ++ ++ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) { ++ struct bfq_queue *pos, *bfqq_item; ++ struct hlist_node *n; ++ ++ /* ++ * Enough queues have been activated shortly after each ++ * other to consider this burst as large. ++ */ ++ bfqd->large_burst = true; ++ bfq_log_bfqq(bfqd, bfqq, "large burst started"); ++ ++ /* ++ * We can now mark all queues in the burst list as ++ * belonging to a large burst. ++ */ ++ hlist_for_each_entry(bfqq_item, &bfqd->burst_list, ++ burst_list_node) { ++ bfq_mark_bfqq_in_large_burst(bfqq_item); ++ bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst"); ++ } ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ bfq_log_bfqq(bfqd, bfqq, "marked in large burst"); ++ ++ /* ++ * From now on, and until the current burst finishes, any ++ * new queue being activated shortly after the last queue ++ * was inserted in the burst can be immediately marked as ++ * belonging to a large burst. So the burst list is not ++ * needed any more. Remove it. ++ */ ++ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list, ++ burst_list_node) ++ hlist_del_init(&pos->burst_list_node); ++ } else /* ++ * Burst not yet large: add bfqq to the burst list. Do ++ * not increment the ref counter for bfqq, because bfqq ++ * is removed from the burst list before freeing bfqq ++ * in put_queue. ++ */ ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++} ++ ++/* ++ * If many queues belonging to the same group happen to be created ++ * shortly after each other, then the processes associated with these ++ * queues have typically a common goal. In particular, bursts of queue ++ * creations are usually caused by services or applications that spawn ++ * many parallel threads/processes. Examples are systemd during boot, ++ * or git grep. To help these processes get their job done as soon as ++ * possible, it is usually better to not grant either weight-raising ++ * or device idling to their queues. ++ * ++ * In this comment we describe, firstly, the reasons why this fact ++ * holds, and, secondly, the next function, which implements the main ++ * steps needed to properly mark these queues so that they can then be ++ * treated in a different way. ++ * ++ * The above services or applications benefit mostly from a high ++ * throughput: the quicker the requests of the activated queues are ++ * cumulatively served, the sooner the target job of these queues gets ++ * completed. As a consequence, weight-raising any of these queues, ++ * which also implies idling the device for it, is almost always ++ * counterproductive. In most cases it just lowers throughput. ++ * ++ * On the other hand, a burst of queue creations may be caused also by ++ * the start of an application that does not consist of a lot of ++ * parallel I/O-bound threads. In fact, with a complex application, ++ * several short processes may need to be executed to start-up the ++ * application. In this respect, to start an application as quickly as ++ * possible, the best thing to do is in any case to privilege the I/O ++ * related to the application with respect to all other ++ * I/O. Therefore, the best strategy to start as quickly as possible ++ * an application that causes a burst of queue creations is to ++ * weight-raise all the queues created during the burst. This is the ++ * exact opposite of the best strategy for the other type of bursts. ++ * ++ * In the end, to take the best action for each of the two cases, the ++ * two types of bursts need to be distinguished. Fortunately, this ++ * seems relatively easy, by looking at the sizes of the bursts. In ++ * particular, we found a threshold such that only bursts with a ++ * larger size than that threshold are apparently caused by ++ * services or commands such as systemd or git grep. For brevity, ++ * hereafter we call just 'large' these bursts. BFQ *does not* ++ * weight-raise queues whose creation occurs in a large burst. In ++ * addition, for each of these queues BFQ performs or does not perform ++ * idling depending on which choice boosts the throughput more. The ++ * exact choice depends on the device and request pattern at ++ * hand. ++ * ++ * Unfortunately, false positives may occur while an interactive task ++ * is starting (e.g., an application is being started). The ++ * consequence is that the queues associated with the task do not ++ * enjoy weight raising as expected. Fortunately these false positives ++ * are very rare. They typically occur if some service happens to ++ * start doing I/O exactly when the interactive task starts. ++ * ++ * Turning back to the next function, it implements all the steps ++ * needed to detect the occurrence of a large burst and to properly ++ * mark all the queues belonging to it (so that they can then be ++ * treated in a different way). This goal is achieved by maintaining a ++ * "burst list" that holds, temporarily, the queues that belong to the ++ * burst in progress. The list is then used to mark these queues as ++ * belonging to a large burst if the burst does become large. The main ++ * steps are the following. ++ * ++ * . when the very first queue is created, the queue is inserted into the ++ * list (as it could be the first queue in a possible burst) ++ * ++ * . if the current burst has not yet become large, and a queue Q that does ++ * not yet belong to the burst is activated shortly after the last time ++ * at which a new queue entered the burst list, then the function appends ++ * Q to the burst list ++ * ++ * . if, as a consequence of the previous step, the burst size reaches ++ * the large-burst threshold, then ++ * ++ * . all the queues in the burst list are marked as belonging to a ++ * large burst ++ * ++ * . the burst list is deleted; in fact, the burst list already served ++ * its purpose (keeping temporarily track of the queues in a burst, ++ * so as to be able to mark them as belonging to a large burst in the ++ * previous sub-step), and now is not needed any more ++ * ++ * . the device enters a large-burst mode ++ * ++ * . if a queue Q that does not belong to the burst is created while ++ * the device is in large-burst mode and shortly after the last time ++ * at which a queue either entered the burst list or was marked as ++ * belonging to the current large burst, then Q is immediately marked ++ * as belonging to a large burst. ++ * ++ * . if a queue Q that does not belong to the burst is created a while ++ * later, i.e., not shortly after, than the last time at which a queue ++ * either entered the burst list or was marked as belonging to the ++ * current large burst, then the current burst is deemed as finished and: ++ * ++ * . the large-burst mode is reset if set ++ * ++ * . the burst list is emptied ++ * ++ * . Q is inserted in the burst list, as Q may be the first queue ++ * in a possible new burst (then the burst list contains just Q ++ * after this step). ++ */ ++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq is already in the burst list or is part of a large ++ * burst, or finally has just been split, then there is ++ * nothing else to do. ++ */ ++ if (!hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq) || ++ time_is_after_eq_jiffies(bfqq->split_time + ++ msecs_to_jiffies(10))) ++ return; ++ ++ /* ++ * If bfqq's creation happens late enough, or bfqq belongs to ++ * a different group than the burst group, then the current ++ * burst is finished, and related data structures must be ++ * reset. ++ * ++ * In this respect, consider the special case where bfqq is ++ * the very first queue created after BFQ is selected for this ++ * device. In this case, last_ins_in_burst and ++ * burst_parent_entity are not yet significant when we get ++ * here. But it is easy to verify that, whether or not the ++ * following condition is true, bfqq will end up being ++ * inserted into the burst list. In particular the list will ++ * happen to contain only bfqq. And this is exactly what has ++ * to happen, as bfqq may be the first queue of the first ++ * burst. ++ */ ++ if (time_is_before_jiffies(bfqd->last_ins_in_burst + ++ bfqd->bfq_burst_interval) || ++ bfqq->entity.parent != bfqd->burst_parent_entity) { ++ bfqd->large_burst = false; ++ bfq_reset_burst_list(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "late activation or different group"); ++ goto end; ++ } ++ ++ /* ++ * If we get here, then bfqq is being activated shortly after the ++ * last queue. So, if the current burst is also large, we can mark ++ * bfqq as belonging to this large burst immediately. ++ */ ++ if (bfqd->large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, "marked in burst"); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ goto end; ++ } ++ ++ /* ++ * If we get here, then a large-burst state has not yet been ++ * reached, but bfqq is being activated shortly after the last ++ * queue. Then we add bfqq to the burst. ++ */ ++ bfq_add_to_burst(bfqd, bfqq); ++end: ++ /* ++ * At this point, bfqq either has been added to the current ++ * burst or has caused the current burst to terminate and a ++ * possible new burst to start. In particular, in the second ++ * case, bfqq has become the first queue in the possible new ++ * burst. In both cases last_ins_in_burst needs to be moved ++ * forward. ++ */ ++ bfqd->last_ins_in_burst = jiffies; ++ ++} ++ ++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (entity->budget < entity->service) { ++ pr_crit("budget %d service %d\n", ++ entity->budget, entity->service); ++ BUG(); ++ } ++ return entity->budget - entity->service; ++} ++ ++/* ++ * If enough samples have been computed, return the current max budget ++ * stored in bfqd, which is dynamically updated according to the ++ * estimated disk peak rate; otherwise return the default max budget ++ */ ++static int bfq_max_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget; ++ else ++ return bfqd->bfq_max_budget; ++} ++ ++/* ++ * Return min budget, which is a fraction of the current or default ++ * max budget (trying with 1/32) ++ */ ++static int bfq_min_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget / 32; ++ else ++ return bfqd->bfq_max_budget / 32; ++} ++ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason); ++ ++/* ++ * The next function, invoked after the input queue bfqq switches from ++ * idle to busy, updates the budget of bfqq. The function also tells ++ * whether the in-service queue should be expired, by returning ++ * true. The purpose of expiring the in-service queue is to give bfqq ++ * the chance to possibly preempt the in-service queue, and the reason ++ * for preempting the in-service queue is to achieve one of the two ++ * goals below. ++ * ++ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has ++ * expired because it has remained idle. In particular, bfqq may have ++ * expired for one of the following two reasons: ++ * ++ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and ++ * did not make it to issue a new request before its last request ++ * was served; ++ * ++ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue ++ * a new request before the expiration of the idling-time. ++ * ++ * Even if bfqq has expired for one of the above reasons, the process ++ * associated with the queue may be however issuing requests greedily, ++ * and thus be sensitive to the bandwidth it receives (bfqq may have ++ * remained idle for other reasons: CPU high load, bfqq not enjoying ++ * idling, I/O throttling somewhere in the path from the process to ++ * the I/O scheduler, ...). But if, after every expiration for one of ++ * the above two reasons, bfqq has to wait for the service of at least ++ * one full budget of another queue before being served again, then ++ * bfqq is likely to get a much lower bandwidth or resource time than ++ * its reserved ones. To address this issue, two countermeasures need ++ * to be taken. ++ * ++ * First, the budget and the timestamps of bfqq need to be updated in ++ * a special way on bfqq reactivation: they need to be updated as if ++ * bfqq did not remain idle and did not expire. In fact, if they are ++ * computed as if bfqq expired and remained idle until reactivation, ++ * then the process associated with bfqq is treated as if, instead of ++ * being greedy, it stopped issuing requests when bfqq remained idle, ++ * and restarts issuing requests only on this reactivation. In other ++ * words, the scheduler does not help the process recover the "service ++ * hole" between bfqq expiration and reactivation. As a consequence, ++ * the process receives a lower bandwidth than its reserved one. In ++ * contrast, to recover this hole, the budget must be updated as if ++ * bfqq was not expired at all before this reactivation, i.e., it must ++ * be set to the value of the remaining budget when bfqq was ++ * expired. Along the same line, timestamps need to be assigned the ++ * value they had the last time bfqq was selected for service, i.e., ++ * before last expiration. Thus timestamps need to be back-shifted ++ * with respect to their normal computation (see [1] for more details ++ * on this tricky aspect). ++ * ++ * Secondly, to allow the process to recover the hole, the in-service ++ * queue must be expired too, to give bfqq the chance to preempt it ++ * immediately. In fact, if bfqq has to wait for a full budget of the ++ * in-service queue to be completed, then it may become impossible to ++ * let the process recover the hole, even if the back-shifted ++ * timestamps of bfqq are lower than those of the in-service queue. If ++ * this happens for most or all of the holes, then the process may not ++ * receive its reserved bandwidth. In this respect, it is worth noting ++ * that, being the service of outstanding requests unpreemptible, a ++ * little fraction of the holes may however be unrecoverable, thereby ++ * causing a little loss of bandwidth. ++ * ++ * The last important point is detecting whether bfqq does need this ++ * bandwidth recovery. In this respect, the next function deems the ++ * process associated with bfqq greedy, and thus allows it to recover ++ * the hole, if: 1) the process is waiting for the arrival of a new ++ * request (which implies that bfqq expired for one of the above two ++ * reasons), and 2) such a request has arrived soon. The first ++ * condition is controlled through the flag non_blocking_wait_rq, ++ * while the second through the flag arrived_in_time. If both ++ * conditions hold, then the function computes the budget in the ++ * above-described special way, and signals that the in-service queue ++ * should be expired. Timestamp back-shifting is done later in ++ * __bfq_activate_entity. ++ * ++ * 2. Reduce latency. Even if timestamps are not backshifted to let ++ * the process associated with bfqq recover a service hole, bfqq may ++ * however happen to have, after being (re)activated, a lower finish ++ * timestamp than the in-service queue. That is, the next budget of ++ * bfqq may have to be completed before the one of the in-service ++ * queue. If this is the case, then preempting the in-service queue ++ * allows this goal to be achieved, apart from the unpreemptible, ++ * outstanding requests mentioned above. ++ * ++ * Unfortunately, regardless of which of the above two goals one wants ++ * to achieve, service trees need first to be updated to know whether ++ * the in-service queue must be preempted. To have service trees ++ * correctly updated, the in-service queue must be expired and ++ * rescheduled, and bfqq must be scheduled too. This is one of the ++ * most costly operations (in future versions, the scheduling ++ * mechanism may be re-designed in such a way to make it possible to ++ * know whether preemption is needed without needing to update service ++ * trees). In addition, queue preemptions almost always cause random ++ * I/O, and thus loss of throughput. Because of these facts, the next ++ * function adopts the following simple scheme to avoid both costly ++ * operations and too frequent preemptions: it requests the expiration ++ * of the in-service queue (unconditionally) only for queues that need ++ * to recover a hole, or that either are weight-raised or deserve to ++ * be weight-raised. ++ */ ++static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool arrived_in_time, ++ bool wr_or_deserves_wr) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ /* ++ * In the next compound condition, we check also whether there ++ * is some budget left, because otherwise there is no point in ++ * trying to go on serving bfqq with this same budget: bfqq ++ * would be expired immediately after being selected for ++ * service. This would only cause useless overhead. ++ */ ++ if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time && ++ bfq_bfqq_budget_left(bfqq) > 0) { ++ /* ++ * We do not clear the flag non_blocking_wait_rq here, as ++ * the latter is used in bfq_activate_bfqq to signal ++ * that timestamps need to be back-shifted (and is ++ * cleared right after). ++ */ ++ ++ /* ++ * In next assignment we rely on that either ++ * entity->service or entity->budget are not updated ++ * on expiration if bfqq is empty (see ++ * __bfq_bfqq_recalc_budget). Thus both quantities ++ * remain unchanged after such an expiration, and the ++ * following statement therefore assigns to ++ * entity->budget the remaining budget on such an ++ * expiration. ++ */ ++ BUG_ON(bfqq->max_budget < 0); ++ entity->budget = min_t(unsigned long, ++ bfq_bfqq_budget_left(bfqq), ++ bfqq->max_budget); ++ ++ BUG_ON(entity->budget < 0); ++ ++ /* ++ * At this point, we have used entity->service to get ++ * the budget left (needed for updating ++ * entity->budget). Thus we finally can, and have to, ++ * reset entity->service. The latter must be reset ++ * because bfqq would otherwise be charged again for ++ * the service it has received during its previous ++ * service slot(s). ++ */ ++ entity->service = 0; ++ ++ return true; ++ } ++ ++ /* ++ * We can finally complete expiration, by setting service to 0. ++ */ ++ entity->service = 0; ++ BUG_ON(bfqq->max_budget < 0); ++ entity->budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(bfqq->next_rq, bfqq)); ++ BUG_ON(entity->budget < 0); ++ ++ bfq_clear_bfqq_non_blocking_wait_rq(bfqq); ++ return wr_or_deserves_wr; ++} ++ ++/* ++ * Return the farthest past time instant according to jiffies ++ * macros. ++ */ ++static unsigned long bfq_smallest_from_now(void) ++{ ++ return jiffies - MAX_JIFFY_OFFSET; ++} ++ ++static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ unsigned int old_wr_coeff, ++ bool wr_or_deserves_wr, ++ bool interactive, ++ bool in_burst, ++ bool soft_rt) ++{ ++ if (old_wr_coeff == 1 && wr_or_deserves_wr) { ++ /* start a weight-raising period */ ++ if (interactive) { ++ bfqq->service_from_wr = 0; ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ } else { ++ /* ++ * No interactive weight raising in progress ++ * here: assign minus infinity to ++ * wr_start_at_switch_to_srt, to make sure ++ * that, at the end of the soft-real-time ++ * weight raising periods that is starting ++ * now, no interactive weight-raising period ++ * may be wrongly considered as still in ++ * progress (and thus actually started by ++ * mistake). ++ */ ++ bfqq->wr_start_at_switch_to_srt = ++ bfq_smallest_from_now(); ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff * ++ BFQ_SOFTRT_WEIGHT_FACTOR; ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ } ++ /* ++ * If needed, further reduce budget to make sure it is ++ * close to bfqq's backlog, so as to reduce the ++ * scheduling-error component due to a too large ++ * budget. Do not care about throughput consequences, ++ * but only about latency. Finally, do not assign a ++ * too small budget either, to avoid increasing ++ * latency by causing too frequent expirations. ++ */ ++ bfqq->entity.budget = min_t(unsigned long, ++ bfqq->entity.budget, ++ 2 * bfq_min_budget(bfqd)); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } else if (old_wr_coeff > 1) { ++ if (interactive) { /* update wr coeff and duration */ ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ } else if (in_burst) { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq-> ++ wr_cur_max_time)); ++ } else if (soft_rt) { ++ /* ++ * The application is now or still meeting the ++ * requirements for being deemed soft rt. We ++ * can then correctly and safely (re)charge ++ * the weight-raising duration for the ++ * application with the weight-raising ++ * duration for soft rt applications. ++ * ++ * In particular, doing this recharge now, i.e., ++ * before the weight-raising period for the ++ * application finishes, reduces the probability ++ * of the following negative scenario: ++ * 1) the weight of a soft rt application is ++ * raised at startup (as for any newly ++ * created application), ++ * 2) since the application is not interactive, ++ * at a certain time weight-raising is ++ * stopped for the application, ++ * 3) at that time the application happens to ++ * still have pending requests, and hence ++ * is destined to not have a chance to be ++ * deemed soft rt before these requests are ++ * completed (see the comments to the ++ * function bfq_bfqq_softrt_next_start() ++ * for details on soft rt detection), ++ * 4) these pending requests experience a high ++ * latency because the application is not ++ * weight-raised while they are pending. ++ */ ++ if (bfqq->wr_cur_max_time != ++ bfqd->bfq_wr_rt_max_time) { ++ bfqq->wr_start_at_switch_to_srt = ++ bfqq->last_wr_start_finish; ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff * ++ BFQ_SOFTRT_WEIGHT_FACTOR; ++ bfq_log_bfqq(bfqd, bfqq, ++ "switching to soft_rt wr"); ++ } else ++ bfq_log_bfqq(bfqd, bfqq, ++ "moving forward soft_rt wr duration"); ++ bfqq->last_wr_start_finish = jiffies; ++ } ++ } ++} ++ ++static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ return bfqq->dispatched == 0 && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ bfqd->bfq_wr_min_idle_time); ++} ++ ++static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ int old_wr_coeff, ++ struct request *rq, ++ bool *interactive) ++{ ++ bool soft_rt, in_burst, wr_or_deserves_wr, ++ bfqq_wants_to_preempt, ++ idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq), ++ /* ++ * See the comments on ++ * bfq_bfqq_update_budg_for_activation for ++ * details on the usage of the next variable. ++ */ ++ arrived_in_time = ktime_get_ns() <= ++ RQ_BIC(rq)->ttime.last_end_request + ++ bfqd->bfq_slice_idle * 3; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request non-busy: " ++ "jiffies %lu, in_time %d, idle_long %d busyw %d " ++ "wr_coeff %u", ++ jiffies, arrived_in_time, ++ idle_for_long_time, ++ bfq_bfqq_non_blocking_wait_rq(bfqq), ++ old_wr_coeff); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags); ++ ++ /* ++ * bfqq deserves to be weight-raised if: ++ * - it is sync, ++ * - it does not belong to a large burst, ++ * - it has been idle for enough time or is soft real-time, ++ * - is linked to a bfq_io_cq (it is not shared in any sense) ++ */ ++ in_burst = bfq_bfqq_in_large_burst(bfqq); ++ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && ++ !in_burst && ++ time_is_before_jiffies(bfqq->soft_rt_next_start) && ++ bfqq->dispatched == 0; ++ *interactive = ++ !in_burst && ++ idle_for_long_time; ++ wr_or_deserves_wr = bfqd->low_latency && ++ (bfqq->wr_coeff > 1 || ++ (bfq_bfqq_sync(bfqq) && ++ bfqq->bic && (*interactive || soft_rt))); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request: " ++ "in_burst %d, " ++ "soft_rt %d (next %lu), inter %d, bic %p", ++ bfq_bfqq_in_large_burst(bfqq), soft_rt, ++ bfqq->soft_rt_next_start, ++ *interactive, ++ bfqq->bic); ++ ++ /* ++ * Using the last flag, update budget and check whether bfqq ++ * may want to preempt the in-service queue. ++ */ ++ bfqq_wants_to_preempt = ++ bfq_bfqq_update_budg_for_activation(bfqd, bfqq, ++ arrived_in_time, ++ wr_or_deserves_wr); ++ ++ /* ++ * If bfqq happened to be activated in a burst, but has been ++ * idle for much more than an interactive queue, then we ++ * assume that, in the overall I/O initiated in the burst, the ++ * I/O associated with bfqq is finished. So bfqq does not need ++ * to be treated as a queue belonging to a burst ++ * anymore. Accordingly, we reset bfqq's in_large_burst flag ++ * if set, and remove bfqq from the burst list if it's ++ * there. We do not decrement burst_size, because the fact ++ * that bfqq does not need to belong to the burst list any ++ * more does not invalidate the fact that bfqq was created in ++ * a burst. ++ */ ++ if (likely(!bfq_bfqq_just_created(bfqq)) && ++ idle_for_long_time && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ msecs_to_jiffies(10000))) { ++ hlist_del_init(&bfqq->burst_list_node); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ ++ bfq_clear_bfqq_just_created(bfqq); ++ ++ if (!bfq_bfqq_IO_bound(bfqq)) { ++ if (arrived_in_time) { ++ bfqq->requests_within_timer++; ++ if (bfqq->requests_within_timer >= ++ bfqd->bfq_requests_within_timer) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ } else ++ bfqq->requests_within_timer = 0; ++ bfq_log_bfqq(bfqd, bfqq, "requests in time %d", ++ bfqq->requests_within_timer); ++ } ++ ++ if (bfqd->low_latency) { ++ if (unlikely(time_is_after_jiffies(bfqq->split_time))) ++ /* wraparound */ ++ bfqq->split_time = ++ jiffies - bfqd->bfq_wr_min_idle_time - 1; ++ ++ if (time_is_before_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) { ++ bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq, ++ old_wr_coeff, ++ wr_or_deserves_wr, ++ *interactive, ++ in_burst, ++ soft_rt); ++ ++ if (old_wr_coeff != bfqq->wr_coeff) ++ bfqq->entity.prio_changed = 1; ++ } ++ } ++ ++ bfqq->last_idle_bklogged = jiffies; ++ bfqq->service_from_backlogged = 0; ++ bfq_clear_bfqq_softrt_update(bfqq); ++ ++ bfq_add_bfqq_busy(bfqd, bfqq); ++ ++ /* ++ * Expire in-service queue only if preemption may be needed ++ * for guarantees. In this respect, the function ++ * next_queue_may_preempt just checks a simple, necessary ++ * condition, and not a sufficient condition based on ++ * timestamps. In fact, for the latter condition to be ++ * evaluated, timestamps would need first to be updated, and ++ * this operation is quite costly (see the comments on the ++ * function bfq_bfqq_update_budg_for_activation). ++ */ ++ if (bfqd->in_service_queue && bfqq_wants_to_preempt && ++ bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff && ++ next_queue_may_preempt(bfqd)) { ++ struct bfq_queue *in_serv = ++ bfqd->in_service_queue; ++ BUG_ON(in_serv == bfqq); ++ ++ bfq_bfqq_expire(bfqd, bfqd->in_service_queue, ++ false, BFQ_BFQQ_PREEMPTED); ++ } ++} ++ ++static void bfq_add_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *next_rq, *prev; ++ unsigned int old_wr_coeff = bfqq->wr_coeff; ++ bool interactive = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "size %u %s", ++ blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A"); ++ ++ if (bfqq->wr_coeff > 1) /* queue is being weight-raised */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ bfqq->queued[rq_is_sync(rq)]++; ++ bfqd->queued++; ++ ++ elv_rb_add(&bfqq->sort_list, rq); ++ ++ /* ++ * Check if this request is a better next-to-serve candidate. ++ */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); ++ BUG_ON(!next_rq); ++ bfqq->next_rq = next_rq; ++ ++ /* ++ * Adjust priority tree position, if next_rq changes. ++ */ ++ if (prev != bfqq->next_rq) ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ ++ if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */ ++ bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff, ++ rq, &interactive); ++ else { ++ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) && ++ time_is_before_jiffies( ++ bfqq->last_wr_start_finish + ++ bfqd->bfq_wr_min_inter_arr_async)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd)); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "non-idle wrais starting, " ++ "wr_max_time %u wr_busy %d", ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqd->wr_busy_queues); ++ } ++ if (prev != bfqq->next_rq) ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ /* ++ * Assign jiffies to last_wr_start_finish in the following ++ * cases: ++ * ++ * . if bfqq is not going to be weight-raised, because, for ++ * non weight-raised queues, last_wr_start_finish stores the ++ * arrival time of the last request; as of now, this piece ++ * of information is used only for deciding whether to ++ * weight-raise async queues ++ * ++ * . if bfqq is not weight-raised, because, if bfqq is now ++ * switching to weight-raised, then last_wr_start_finish ++ * stores the time when weight-raising starts ++ * ++ * . if bfqq is interactive, because, regardless of whether ++ * bfqq is currently weight-raised, the weight-raising ++ * period must start or restart (this case is considered ++ * separately because it is not detected by the above ++ * conditions, if bfqq is already weight-raised) ++ * ++ * last_wr_start_finish has to be updated also if bfqq is soft ++ * real-time, because the weight-raising period is constantly ++ * restarted on idle-to-busy transitions for these queues, but ++ * this is already done in bfq_bfqq_handle_idle_busy_switch if ++ * needed. ++ */ ++ if (bfqd->low_latency && ++ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive)) ++ bfqq->last_wr_start_finish = jiffies; ++} ++ ++static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, ++ struct bio *bio) ++{ ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (!bic) ++ return NULL; ++ ++ bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf)); ++ if (bfqq) ++ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); ++ ++ return NULL; ++} ++ ++static sector_t get_sdist(sector_t last_pos, struct request *rq) ++{ ++ sector_t sdist = 0; ++ ++ if (last_pos) { ++ if (last_pos < blk_rq_pos(rq)) ++ sdist = blk_rq_pos(rq) - last_pos; ++ else ++ sdist = last_pos - blk_rq_pos(rq); ++ } ++ ++ return sdist; ++} ++ ++static void bfq_activate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ bfqd->rq_in_driver++; ++} ++ ++static void bfq_deactivate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ BUG_ON(bfqd->rq_in_driver == 0); ++ bfqd->rq_in_driver--; ++} ++ ++static void bfq_remove_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ const int sync = rq_is_sync(rq); ++ ++ /* ++ * NOTE: ++ * (bfqq->entity.service > bfqq->entity.budget) may hold here, ++ * in case of forced dispatches. ++ */ ++ ++ if (bfqq->next_rq == rq) { ++ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ if (rq->queuelist.prev != &rq->queuelist) ++ list_del_init(&rq->queuelist); ++ BUG_ON(bfqq->queued[sync] == 0); ++ bfqq->queued[sync]--; ++ bfqd->queued--; ++ elv_rb_del(&bfqq->sort_list, rq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ bfqq->next_rq = NULL; ++ ++ BUG_ON(bfqq->entity.budget < 0); ++ ++ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) { ++ BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */ ++ bfq_del_bfqq_busy(bfqd, bfqq, false); ++ /* ++ * bfqq emptied. In normal operation, when ++ * bfqq is empty, bfqq->entity.service and ++ * bfqq->entity.budget must contain, ++ * respectively, the service received and the ++ * budget used last time bfqq emptied. These ++ * facts do not hold in this case, as at least ++ * this last removal occurred while bfqq is ++ * not in service. To avoid inconsistencies, ++ * reset both bfqq->entity.service and ++ * bfqq->entity.budget, if bfqq has still a ++ * process that may issue I/O requests to it. ++ */ ++ bfqq->entity.budget = bfqq->entity.service = 0; ++ } ++ ++ /* ++ * Remove queue from request-position tree as it is empty. ++ */ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ } else { ++ BUG_ON(!bfqq->next_rq); ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ ++ if (rq->cmd_flags & REQ_META) { ++ BUG_ON(bfqq->meta_pending == 0); ++ bfqq->meta_pending--; ++ } ++ bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags); ++} ++ ++static enum elv_merge bfq_merge(struct request_queue *q, struct request **req, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct request *__rq; ++ ++ __rq = bfq_find_rq_fmerge(bfqd, bio); ++ if (__rq && elv_bio_merge_ok(__rq, bio)) { ++ *req = __rq; ++ return ELEVATOR_FRONT_MERGE; ++ } ++ ++ return ELEVATOR_NO_MERGE; ++} ++ ++static void bfq_merged_request(struct request_queue *q, struct request *req, ++ enum elv_merge type) ++{ ++ if (type == ELEVATOR_FRONT_MERGE && ++ rb_prev(&req->rb_node) && ++ blk_rq_pos(req) < ++ blk_rq_pos(container_of(rb_prev(&req->rb_node), ++ struct request, rb_node))) { ++ struct bfq_queue *bfqq = RQ_BFQQ(req); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *prev, *next_rq; ++ ++ /* Reposition request in its sort_list */ ++ elv_rb_del(&bfqq->sort_list, req); ++ elv_rb_add(&bfqq->sort_list, req); ++ /* Choose next request to be served for bfqq */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, ++ bfqd->last_position); ++ BUG_ON(!next_rq); ++ bfqq->next_rq = next_rq; ++ /* ++ * If next_rq changes, update both the queue's budget to ++ * fit the new request and the queue's position in its ++ * rq_pos_tree. ++ */ ++ if (prev != bfqq->next_rq) { ++ bfq_updated_next_req(bfqd, bfqq); ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ } ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static void bfq_bio_merged(struct request_queue *q, struct request *req, ++ struct bio *bio) ++{ ++ bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf); ++} ++#endif ++ ++static void bfq_merged_requests(struct request_queue *q, struct request *rq, ++ struct request *next) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next); ++ ++ /* ++ * If next and rq belong to the same bfq_queue and next is older ++ * than rq, then reposition rq in the fifo (by substituting next ++ * with rq). Otherwise, if next and rq belong to different ++ * bfq_queues, never reposition rq: in fact, we would have to ++ * reposition it with respect to next's position in its own fifo, ++ * which would most certainly be too expensive with respect to ++ * the benefits. ++ */ ++ if (bfqq == next_bfqq && ++ !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && ++ next->fifo_time < rq->fifo_time) { ++ list_del_init(&rq->queuelist); ++ list_replace_init(&next->queuelist, &rq->queuelist); ++ rq->fifo_time = next->fifo_time; ++ } ++ ++ if (bfqq->next_rq == next) ++ bfqq->next_rq = rq; ++ ++ bfq_remove_request(next); ++ bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); ++} ++ ++/* Must be called with bfqq != NULL */ ++static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) ++{ ++ BUG_ON(!bfqq); ++ ++ if (bfq_bfqq_busy(bfqq)) { ++ bfqq->bfqd->wr_busy_queues--; ++ BUG_ON(bfqq->bfqd->wr_busy_queues < 0); ++ } ++ bfqq->wr_coeff = 1; ++ bfqq->wr_cur_max_time = 0; ++ bfqq->last_wr_start_finish = jiffies; ++ /* ++ * Trigger a weight change on the next invocation of ++ * __bfq_entity_update_weight_prio. ++ */ ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ bfqq->last_wr_start_finish, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d", ++ bfqq->bfqd->wr_busy_queues); ++} ++ ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ if (bfqg->async_bfqq[i][j]) ++ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]); ++ if (bfqg->async_idle_bfqq) ++ bfq_bfqq_end_wr(bfqg->async_idle_bfqq); ++} ++ ++static void bfq_end_wr(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ bfq_end_wr_async(bfqd); ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++} ++ ++static sector_t bfq_io_struct_pos(void *io_struct, bool request) ++{ ++ if (request) ++ return blk_rq_pos(io_struct); ++ else ++ return ((struct bio *)io_struct)->bi_iter.bi_sector; ++} ++ ++static int bfq_rq_close_to_sector(void *io_struct, bool request, ++ sector_t sector) ++{ ++ return abs(bfq_io_struct_pos(io_struct, request) - sector) <= ++ BFQQ_CLOSE_THR; ++} ++ ++static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ sector_t sector) ++{ ++ struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ struct rb_node *parent, *node; ++ struct bfq_queue *__bfqq; ++ ++ if (RB_EMPTY_ROOT(root)) ++ return NULL; ++ ++ /* ++ * First, if we find a request starting at the end of the last ++ * request, choose it. ++ */ ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL); ++ if (__bfqq) ++ return __bfqq; ++ ++ /* ++ * If the exact sector wasn't found, the parent of the NULL leaf ++ * will contain the closest sector (rq_pos_tree sorted by ++ * next_request position). ++ */ ++ __bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ if (blk_rq_pos(__bfqq->next_rq) < sector) ++ node = rb_next(&__bfqq->pos_node); ++ else ++ node = rb_prev(&__bfqq->pos_node); ++ if (!node) ++ return NULL; ++ ++ __bfqq = rb_entry(node, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ return NULL; ++} ++ ++static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd, ++ struct bfq_queue *cur_bfqq, ++ sector_t sector) ++{ ++ struct bfq_queue *bfqq; ++ ++ /* ++ * We shall notice if some of the queues are cooperating, ++ * e.g., working closely on the same area of the device. In ++ * that case, we can group them together and: 1) don't waste ++ * time idling, and 2) serve the union of their requests in ++ * the best possible order for throughput. ++ */ ++ bfqq = bfqq_find_close(bfqd, cur_bfqq, sector); ++ if (!bfqq || bfqq == cur_bfqq) ++ return NULL; ++ ++ return bfqq; ++} ++ ++static struct bfq_queue * ++bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ int process_refs, new_process_refs; ++ struct bfq_queue *__bfqq; ++ ++ /* ++ * If there are no process references on the new_bfqq, then it is ++ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain ++ * may have dropped their last reference (not just their last process ++ * reference). ++ */ ++ if (!bfqq_process_refs(new_bfqq)) ++ return NULL; ++ ++ /* Avoid a circular list and skip interim queue merges. */ ++ while ((__bfqq = new_bfqq->new_bfqq)) { ++ if (__bfqq == bfqq) ++ return NULL; ++ new_bfqq = __bfqq; ++ } ++ ++ process_refs = bfqq_process_refs(bfqq); ++ new_process_refs = bfqq_process_refs(new_bfqq); ++ /* ++ * If the process for the bfqq has gone away, there is no ++ * sense in merging the queues. ++ */ ++ if (process_refs == 0 || new_process_refs == 0) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", ++ new_bfqq->pid); ++ ++ /* ++ * Merging is just a redirection: the requests of the process ++ * owning one of the two queues are redirected to the other queue. ++ * The latter queue, in its turn, is set as shared if this is the ++ * first time that the requests of some process are redirected to ++ * it. ++ * ++ * We redirect bfqq to new_bfqq and not the opposite, because we ++ * are in the context of the process owning bfqq, hence we have ++ * the io_cq of this process. So we can immediately configure this ++ * io_cq to redirect the requests of the process to new_bfqq. ++ * ++ * NOTE, even if new_bfqq coincides with the in-service queue, the ++ * io_cq of new_bfqq is not available, because, if the in-service ++ * queue is shared, bfqd->in_service_bic may not point to the ++ * io_cq of the in-service queue. ++ * Redirecting the requests of the process owning bfqq to the ++ * currently in-service queue is in any case the best option, as ++ * we feed the in-service queue with new requests close to the ++ * last request served and, by doing so, hopefully increase the ++ * throughput. ++ */ ++ bfqq->new_bfqq = new_bfqq; ++ new_bfqq->ref += process_refs; ++ return new_bfqq; ++} ++ ++static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, ++ struct bfq_queue *new_bfqq) ++{ ++ if (bfq_too_late_for_merging(new_bfqq)) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "too late for bfq%d to be merged", ++ new_bfqq->pid); ++ return false; ++ } ++ ++ if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) || ++ (bfqq->ioprio_class != new_bfqq->ioprio_class)) ++ return false; ++ ++ /* ++ * If either of the queues has already been detected as seeky, ++ * then merging it with the other queue is unlikely to lead to ++ * sequential I/O. ++ */ ++ if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq)) ++ return false; ++ ++ /* ++ * Interleaved I/O is known to be done by (some) applications ++ * only for reads, so it does not make sense to merge async ++ * queues. ++ */ ++ if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq)) ++ return false; ++ ++ return true; ++} ++ ++/* ++ * Attempt to schedule a merge of bfqq with the currently in-service ++ * queue or with a close queue among the scheduled queues. Return ++ * NULL if no merge was scheduled, a pointer to the shared bfq_queue ++ * structure otherwise. ++ * ++ * The OOM queue is not allowed to participate to cooperation: in fact, since ++ * the requests temporarily redirected to the OOM queue could be redirected ++ * again to dedicated queues at any time, the state needed to correctly ++ * handle merging with the OOM queue would be quite complex and expensive ++ * to maintain. Besides, in such a critical condition as an out of memory, ++ * the benefits of queue merging may be little relevant, or even negligible. ++ * ++ * WARNING: queue merging may impair fairness among non-weight raised ++ * queues, for at least two reasons: 1) the original weight of a ++ * merged queue may change during the merged state, 2) even being the ++ * weight the same, a merged queue may be bloated with many more ++ * requests than the ones produced by its originally-associated ++ * process. ++ */ ++static struct bfq_queue * ++bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ void *io_struct, bool request) ++{ ++ struct bfq_queue *in_service_bfqq, *new_bfqq; ++ ++ /* ++ * Prevent bfqq from being merged if it has been created too ++ * long ago. The idea is that true cooperating processes, and ++ * thus their associated bfq_queues, are supposed to be ++ * created shortly after each other. This is the case, e.g., ++ * for KVM/QEMU and dump I/O threads. Basing on this ++ * assumption, the following filtering greatly reduces the ++ * probability that two non-cooperating processes, which just ++ * happen to do close I/O for some short time interval, have ++ * their queues merged by mistake. ++ */ ++ if (bfq_too_late_for_merging(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "would have looked for coop, but too late"); ++ return NULL; ++ } ++ ++ if (bfqq->new_bfqq) ++ return bfqq->new_bfqq; ++ ++ if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) ++ return NULL; ++ ++ /* If there is only one backlogged queue, don't search. */ ++ if (bfq_tot_busy_queues(bfqd) == 1) ++ return NULL; ++ ++ in_service_bfqq = bfqd->in_service_queue; ++ ++ if (in_service_bfqq && in_service_bfqq != bfqq && ++ likely(in_service_bfqq != &bfqd->oom_bfqq) && ++ bfq_rq_close_to_sector(io_struct, request, bfqd->in_serv_last_pos) && ++ bfqq->entity.parent == in_service_bfqq->entity.parent && ++ bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) { ++ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq); ++ if (new_bfqq) ++ return new_bfqq; ++ } ++ /* ++ * Check whether there is a cooperator among currently scheduled ++ * queues. The only thing we need is that the bio/request is not ++ * NULL, as we need it to establish whether a cooperator exists. ++ */ ++ new_bfqq = bfq_find_close_cooperator(bfqd, bfqq, ++ bfq_io_struct_pos(io_struct, request)); ++ ++ BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent); ++ ++ if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) && ++ bfq_may_be_close_cooperator(bfqq, new_bfqq)) ++ return bfq_setup_merge(bfqq, new_bfqq); ++ ++ return NULL; ++} ++ ++static void bfq_bfqq_save_state(struct bfq_queue *bfqq) ++{ ++ struct bfq_io_cq *bic = bfqq->bic; ++ ++ /* ++ * If !bfqq->bic, the queue is already shared or its requests ++ * have already been redirected to a shared queue; both idle window ++ * and weight raising state have already been saved. Do nothing. ++ */ ++ if (!bic) ++ return; ++ ++ bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq); ++ bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq); ++ bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq); ++ bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node); ++ if (unlikely(bfq_bfqq_just_created(bfqq) && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ bfqq->bfqd->low_latency)) { ++ /* ++ * bfqq being merged ritgh after being created: bfqq ++ * would have deserved interactive weight raising, but ++ * did not make it to be set in a weight-raised state, ++ * because of this early merge. Store directly the ++ * weight-raising state that would have been assigned ++ * to bfqq, so that to avoid that bfqq unjustly fails ++ * to enjoy weight raising if split soon. ++ */ ++ bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff; ++ bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd); ++ bic->saved_last_wr_start_finish = jiffies; ++ } else { ++ bic->saved_wr_coeff = bfqq->wr_coeff; ++ bic->saved_wr_start_at_switch_to_srt = ++ bfqq->wr_start_at_switch_to_srt; ++ bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish; ++ bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time; ++ } ++ BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish)); ++} ++ ++static void bfq_get_bic_reference(struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq->bic has a non-NULL value, the bic to which it belongs ++ * is about to begin using a shared bfq_queue. ++ */ ++ if (bfqq->bic) ++ atomic_long_inc(&bfqq->bic->icq.ioc->refcount); ++} ++ ++static void ++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", ++ (unsigned long) new_bfqq->pid); ++ /* Save weight raising and idle window of the merged queues */ ++ bfq_bfqq_save_state(bfqq); ++ bfq_bfqq_save_state(new_bfqq); ++ if (bfq_bfqq_IO_bound(bfqq)) ++ bfq_mark_bfqq_IO_bound(new_bfqq); ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ /* ++ * If bfqq is weight-raised, then let new_bfqq inherit ++ * weight-raising. To reduce false positives, neglect the case ++ * where bfqq has just been created, but has not yet made it ++ * to be weight-raised (which may happen because EQM may merge ++ * bfqq even before bfq_add_request is executed for the first ++ * time for bfqq). Handling this case would however be very ++ * easy, thanks to the flag just_created. ++ */ ++ if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) { ++ new_bfqq->wr_coeff = bfqq->wr_coeff; ++ new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time; ++ new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish; ++ new_bfqq->wr_start_at_switch_to_srt = ++ bfqq->wr_start_at_switch_to_srt; ++ if (bfq_bfqq_busy(new_bfqq)) { ++ bfqd->wr_busy_queues++; ++ BUG_ON(bfqd->wr_busy_queues > ++ bfq_tot_busy_queues(bfqd)); ++ } ++ ++ new_bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, new_bfqq, ++ "wr start after merge with %d, rais_max_time %u", ++ bfqq->pid, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */ ++ bfqq->wr_coeff = 1; ++ bfqq->entity.prio_changed = 1; ++ if (bfq_bfqq_busy(bfqq)) { ++ bfqd->wr_busy_queues--; ++ BUG_ON(bfqd->wr_busy_queues < 0); ++ } ++ ++ } ++ ++ bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d", ++ bfqd->wr_busy_queues); ++ ++ /* ++ * Grab a reference to the bic, to prevent it from being destroyed ++ * before being possibly touched by a bfq_split_bfqq(). ++ */ ++ bfq_get_bic_reference(bfqq); ++ bfq_get_bic_reference(new_bfqq); ++ /* ++ * Merge queues (that is, let bic redirect its requests to new_bfqq) ++ */ ++ bic_set_bfqq(bic, new_bfqq, 1); ++ bfq_mark_bfqq_coop(new_bfqq); ++ /* ++ * new_bfqq now belongs to at least two bics (it is a shared queue): ++ * set new_bfqq->bic to NULL. bfqq either: ++ * - does not belong to any bic any more, and hence bfqq->bic must ++ * be set to NULL, or ++ * - is a queue whose owning bics have already been redirected to a ++ * different queue, hence the queue is destined to not belong to ++ * any bic soon and bfqq->bic is already NULL (therefore the next ++ * assignment causes no harm). ++ */ ++ new_bfqq->bic = NULL; ++ bfqq->bic = NULL; ++ /* release process reference to bfqq */ ++ bfq_put_queue(bfqq); ++} ++ ++static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ bool is_sync = op_is_sync(bio->bi_opf); ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq, *new_bfqq; ++ ++ /* ++ * Disallow merge of a sync bio into an async request. ++ */ ++ if (is_sync && !rq_is_sync(rq)) ++ return false; ++ ++ /* ++ * Lookup the bfqq that this bio will be queued with. Allow ++ * merge only if rq is queued there. ++ * Queue lock is held here. ++ */ ++ bic = bfq_bic_lookup(bfqd, current->io_context); ++ if (!bic) ++ return false; ++ ++ bfqq = bic_to_bfqq(bic, is_sync); ++ /* ++ * We take advantage of this function to perform an early merge ++ * of the queues of possible cooperating processes. ++ */ ++ if (bfqq) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false); ++ if (new_bfqq) { ++ bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq); ++ /* ++ * If we get here, the bio will be queued in the ++ * shared queue, i.e., new_bfqq, so use new_bfqq ++ * to decide whether bio and rq can be merged. ++ */ ++ bfqq = new_bfqq; ++ } ++ } ++ ++ return bfqq == RQ_BFQQ(rq); ++} ++ ++static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq, ++ struct request *next) ++{ ++ return RQ_BFQQ(rq) == RQ_BFQQ(next); ++} ++ ++/* ++ * Set the maximum time for the in-service queue to consume its ++ * budget. This prevents seeky processes from lowering the throughput. ++ * In practice, a time-slice service scheme is used with seeky ++ * processes. ++ */ ++static void bfq_set_budget_timeout(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ unsigned int timeout_coeff; ++ ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) ++ timeout_coeff = 1; ++ else ++ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; ++ ++ bfqd->last_budget_start = ktime_get(); ++ ++ bfqq->budget_timeout = jiffies + ++ bfqd->bfq_timeout * timeout_coeff; ++ ++ bfq_log_bfqq(bfqd, bfqq, "%u", ++ jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff)); ++} ++ ++static void __bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq) { ++ bfqg_stats_update_avg_queue_size(bfqq_group(bfqq)); ++ bfq_mark_bfqq_must_alloc(bfqq); ++ bfq_clear_bfqq_fifo_expire(bfqq); ++ ++ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ if (time_is_before_jiffies(bfqq->last_wr_start_finish) && ++ bfqq->wr_coeff > 1 && ++ bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ time_is_before_jiffies(bfqq->budget_timeout)) { ++ /* ++ * For soft real-time queues, move the start ++ * of the weight-raising period forward by the ++ * time the queue has not received any ++ * service. Otherwise, a relatively long ++ * service delay is likely to cause the ++ * weight-raising period of the queue to end, ++ * because of the short duration of the ++ * weight-raising period of a soft real-time ++ * queue. It is worth noting that this move ++ * is not so dangerous for the other queues, ++ * because soft real-time queues are not ++ * greedy. ++ * ++ * To not add a further variable, we use the ++ * overloaded field budget_timeout to ++ * determine for how long the queue has not ++ * received service, i.e., how much time has ++ * elapsed since the queue expired. However, ++ * this is a little imprecise, because ++ * budget_timeout is set to jiffies if bfqq ++ * not only expires, but also remains with no ++ * request. ++ */ ++ if (time_after(bfqq->budget_timeout, ++ bfqq->last_wr_start_finish)) ++ bfqq->last_wr_start_finish += ++ jiffies - bfqq->budget_timeout; ++ else ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (time_is_after_jiffies(bfqq->last_wr_start_finish)) { ++ pr_crit( ++ "BFQ WARNING:last %lu budget %lu jiffies %lu", ++ bfqq->last_wr_start_finish, ++ bfqq->budget_timeout, ++ jiffies); ++ pr_crit("diff %lu", jiffies - ++ max_t(unsigned long, ++ bfqq->last_wr_start_finish, ++ bfqq->budget_timeout)); ++ bfqq->last_wr_start_finish = jiffies; ++ } ++ } ++ ++ bfq_set_budget_timeout(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "cur-budget = %d prio_class %d", ++ bfqq->entity.budget, bfqq->ioprio_class); ++ } else ++ bfq_log(bfqd, "NULL"); ++ ++ bfqd->in_service_queue = bfqq; ++} ++ ++/* ++ * Get and set a new queue for service. ++ */ ++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd); ++ ++ __bfq_set_in_service_queue(bfqd, bfqq); ++ return bfqq; ++} ++ ++static void bfq_arm_slice_timer(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ struct bfq_io_cq *bic; ++ u32 sl; ++ ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ /* Processes have exited, don't wait. */ ++ bic = bfqd->in_service_bic; ++ if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0) ++ return; ++ ++ bfq_mark_bfqq_wait_request(bfqq); ++ ++ /* ++ * We don't want to idle for seeks, but we do want to allow ++ * fair distribution of slice time for a process doing back-to-back ++ * seeks. So allow a little bit of time for him to submit a new rq. ++ * ++ * To prevent processes with (partly) seeky workloads from ++ * being too ill-treated, grant them a small fraction of the ++ * assigned budget before reducing the waiting time to ++ * BFQ_MIN_TT. This happened to help reduce latency. ++ */ ++ sl = bfqd->bfq_slice_idle; ++ /* ++ * Unless the queue is being weight-raised or the scenario is ++ * asymmetric, grant only minimum idle time if the queue ++ * is seeky. A long idling is preserved for a weight-raised ++ * queue, or, more in general, in an asymemtric scenario, ++ * because a long idling is needed for guaranteeing to a queue ++ * its reserved share of the throughput (in particular, it is ++ * needed if the queue has a higher weight than some other ++ * queue). ++ */ ++ if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 && ++ bfq_symmetric_scenario(bfqd)) ++ sl = min_t(u32, sl, BFQ_MIN_TT); ++ ++ bfqd->last_idling_start = ktime_get(); ++ hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl), ++ HRTIMER_MODE_REL); ++ bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); ++ bfq_log(bfqd, "arm idle: %ld/%ld ms", ++ sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC); ++} ++ ++/* ++ * In autotuning mode, max_budget is dynamically recomputed as the ++ * amount of sectors transferred in timeout at the estimated peak ++ * rate. This enables BFQ to utilize a full timeslice with a full ++ * budget, even if the in-service queue is served at peak rate. And ++ * this maximises throughput with sequential workloads. ++ */ ++static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd) ++{ ++ return (u64)bfqd->peak_rate * USEC_PER_MSEC * ++ jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT; ++} ++ ++/* ++ * Update parameters related to throughput and responsiveness, as a ++ * function of the estimated peak rate. See comments on ++ * bfq_calc_max_budget(), and on the ref_wr_duration array. ++ */ ++static void update_thr_responsiveness_params(struct bfq_data *bfqd) ++{ ++ if (bfqd->bfq_user_max_budget == 0) { ++ bfqd->bfq_max_budget = ++ bfq_calc_max_budget(bfqd); ++ BUG_ON(bfqd->bfq_max_budget < 0); ++ bfq_log(bfqd, "new max_budget = %d", ++ bfqd->bfq_max_budget); ++ } ++} ++ ++static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq) ++{ ++ if (rq != NULL) { /* new rq dispatch now, reset accordingly */ ++ bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ; ++ bfqd->peak_rate_samples = 1; ++ bfqd->sequential_samples = 0; ++ bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size = ++ blk_rq_sectors(rq); ++ } else /* no new rq dispatched, just reset the number of samples */ ++ bfqd->peak_rate_samples = 0; /* full re-init on next disp. */ ++ ++ bfq_log(bfqd, ++ "at end, sample %u/%u tot_sects %llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ bfqd->tot_sectors_dispatched); ++} ++ ++static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq) ++{ ++ u32 rate, weight, divisor; ++ ++ /* ++ * For the convergence property to hold (see comments on ++ * bfq_update_peak_rate()) and for the assessment to be ++ * reliable, a minimum number of samples must be present, and ++ * a minimum amount of time must have elapsed. If not so, do ++ * not compute new rate. Just reset parameters, to get ready ++ * for a new evaluation attempt. ++ */ ++ if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES || ++ bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) { ++ bfq_log(bfqd, ++ "only resetting, delta_first %lluus samples %d", ++ bfqd->delta_from_first>>10, bfqd->peak_rate_samples); ++ goto reset_computation; ++ } ++ ++ /* ++ * If a new request completion has occurred after last ++ * dispatch, then, to approximate the rate at which requests ++ * have been served by the device, it is more precise to ++ * extend the observation interval to the last completion. ++ */ ++ bfqd->delta_from_first = ++ max_t(u64, bfqd->delta_from_first, ++ bfqd->last_completion - bfqd->first_dispatch); ++ ++ BUG_ON(bfqd->delta_from_first == 0); ++ /* ++ * Rate computed in sects/usec, and not sects/nsec, for ++ * precision issues. ++ */ ++ rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT, ++ div_u64(bfqd->delta_from_first, NSEC_PER_USEC)); ++ ++ bfq_log(bfqd, ++"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)", ++ bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ rate > 20<<BFQ_RATE_SHIFT); ++ ++ /* ++ * Peak rate not updated if: ++ * - the percentage of sequential dispatches is below 3/4 of the ++ * total, and rate is below the current estimated peak rate ++ * - rate is unreasonably high (> 20M sectors/sec) ++ */ ++ if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 && ++ rate <= bfqd->peak_rate) || ++ rate > 20<<BFQ_RATE_SHIFT) { ++ bfq_log(bfqd, ++ "goto reset, samples %u/%u rate/peak %llu/%llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ goto reset_computation; ++ } else { ++ bfq_log(bfqd, ++ "do update, samples %u/%u rate/peak %llu/%llu", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ ((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT), ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ } ++ ++ /* ++ * We have to update the peak rate, at last! To this purpose, ++ * we use a low-pass filter. We compute the smoothing constant ++ * of the filter as a function of the 'weight' of the new ++ * measured rate. ++ * ++ * As can be seen in next formulas, we define this weight as a ++ * quantity proportional to how sequential the workload is, ++ * and to how long the observation time interval is. ++ * ++ * The weight runs from 0 to 8. The maximum value of the ++ * weight, 8, yields the minimum value for the smoothing ++ * constant. At this minimum value for the smoothing constant, ++ * the measured rate contributes for half of the next value of ++ * the estimated peak rate. ++ * ++ * So, the first step is to compute the weight as a function ++ * of how sequential the workload is. Note that the weight ++ * cannot reach 9, because bfqd->sequential_samples cannot ++ * become equal to bfqd->peak_rate_samples, which, in its ++ * turn, holds true because bfqd->sequential_samples is not ++ * incremented for the first sample. ++ */ ++ weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples; ++ ++ /* ++ * Second step: further refine the weight as a function of the ++ * duration of the observation interval. ++ */ ++ weight = min_t(u32, 8, ++ div_u64(weight * bfqd->delta_from_first, ++ BFQ_RATE_REF_INTERVAL)); ++ ++ /* ++ * Divisor ranging from 10, for minimum weight, to 2, for ++ * maximum weight. ++ */ ++ divisor = 10 - weight; ++ BUG_ON(divisor == 0); ++ ++ /* ++ * Finally, update peak rate: ++ * ++ * peak_rate = peak_rate * (divisor-1) / divisor + rate / divisor ++ */ ++ bfqd->peak_rate *= divisor-1; ++ bfqd->peak_rate /= divisor; ++ rate /= divisor; /* smoothing constant alpha = 1/divisor */ ++ ++ bfq_log(bfqd, ++ "divisor %d tmp_peak_rate %llu tmp_rate %u", ++ divisor, ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT), ++ (u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT)); ++ ++ BUG_ON(bfqd->peak_rate == 0); ++ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT); ++ ++ bfqd->peak_rate += rate; ++ ++ /* ++ * For a very slow device, bfqd->peak_rate can reach 0 (see ++ * the minimum representable values reported in the comments ++ * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid ++ * divisions by zero where bfqd->peak_rate is used as a ++ * divisor. ++ */ ++ bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate); ++ ++ update_thr_responsiveness_params(bfqd); ++ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT); ++ ++reset_computation: ++ bfq_reset_rate_computation(bfqd, rq); ++} ++ ++/* ++ * Update the read/write peak rate (the main quantity used for ++ * auto-tuning, see update_thr_responsiveness_params()). ++ * ++ * It is not trivial to estimate the peak rate (correctly): because of ++ * the presence of sw and hw queues between the scheduler and the ++ * device components that finally serve I/O requests, it is hard to ++ * say exactly when a given dispatched request is served inside the ++ * device, and for how long. As a consequence, it is hard to know ++ * precisely at what rate a given set of requests is actually served ++ * by the device. ++ * ++ * On the opposite end, the dispatch time of any request is trivially ++ * available, and, from this piece of information, the "dispatch rate" ++ * of requests can be immediately computed. So, the idea in the next ++ * function is to use what is known, namely request dispatch times ++ * (plus, when useful, request completion times), to estimate what is ++ * unknown, namely in-device request service rate. ++ * ++ * The main issue is that, because of the above facts, the rate at ++ * which a certain set of requests is dispatched over a certain time ++ * interval can vary greatly with respect to the rate at which the ++ * same requests are then served. But, since the size of any ++ * intermediate queue is limited, and the service scheme is lossless ++ * (no request is silently dropped), the following obvious convergence ++ * property holds: the number of requests dispatched MUST become ++ * closer and closer to the number of requests completed as the ++ * observation interval grows. This is the key property used in ++ * the next function to estimate the peak service rate as a function ++ * of the observed dispatch rate. The function assumes to be invoked ++ * on every request dispatch. ++ */ ++static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq) ++{ ++ u64 now_ns = ktime_get_ns(); ++ ++ if (bfqd->peak_rate_samples == 0) { /* first dispatch */ ++ bfq_log(bfqd, ++ "goto reset, samples %d", ++ bfqd->peak_rate_samples) ; ++ bfq_reset_rate_computation(bfqd, rq); ++ goto update_last_values; /* will add one sample */ ++ } ++ ++ /* ++ * Device idle for very long: the observation interval lasting ++ * up to this dispatch cannot be a valid observation interval ++ * for computing a new peak rate (similarly to the late- ++ * completion event in bfq_completed_request()). Go to ++ * update_rate_and_reset to have the following three steps ++ * taken: ++ * - close the observation interval at the last (previous) ++ * request dispatch or completion ++ * - compute rate, if possible, for that observation interval ++ * - start a new observation interval with this dispatch ++ */ ++ if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC && ++ bfqd->rq_in_driver == 0) { ++ bfq_log(bfqd, ++"jumping to updating&resetting delta_last %lluus samples %d", ++ (now_ns - bfqd->last_dispatch)>>10, ++ bfqd->peak_rate_samples) ; ++ goto update_rate_and_reset; ++ } ++ ++ /* Update sampling information */ ++ bfqd->peak_rate_samples++; ++ ++ if ((bfqd->rq_in_driver > 0 || ++ now_ns - bfqd->last_completion < BFQ_MIN_TT) ++ && !BFQ_RQ_SEEKY(bfqd, bfqd->last_position, rq)) ++ bfqd->sequential_samples++; ++ ++ bfqd->tot_sectors_dispatched += blk_rq_sectors(rq); ++ ++ /* Reset max observed rq size every 32 dispatches */ ++ if (likely(bfqd->peak_rate_samples % 32)) ++ bfqd->last_rq_max_size = ++ max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size); ++ else ++ bfqd->last_rq_max_size = blk_rq_sectors(rq); ++ ++ bfqd->delta_from_first = now_ns - bfqd->first_dispatch; ++ ++ bfq_log(bfqd, ++ "added samples %u/%u tot_sects %llu delta_first %lluus", ++ bfqd->peak_rate_samples, bfqd->sequential_samples, ++ bfqd->tot_sectors_dispatched, ++ bfqd->delta_from_first>>10); ++ ++ /* Target observation interval not yet reached, go on sampling */ ++ if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL) ++ goto update_last_values; ++ ++update_rate_and_reset: ++ bfq_update_rate_reset(bfqd, rq); ++update_last_values: ++ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ if (RQ_BFQQ(rq) == bfqd->in_service_queue) ++ bfqd->in_serv_last_pos = bfqd->last_position; ++ bfqd->last_dispatch = now_ns; ++ ++ bfq_log(bfqd, ++ "delta_first %lluus last_pos %llu peak_rate %llu", ++ (now_ns - bfqd->first_dispatch)>>10, ++ (unsigned long long) bfqd->last_position, ++ ((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT)); ++ bfq_log(bfqd, ++ "samples at end %d", bfqd->peak_rate_samples); ++} ++ ++/* ++ * Move request from internal lists to the dispatch list of the request queue ++ */ ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * For consistency, the next instruction should have been executed ++ * after removing the request from the queue and dispatching it. ++ * We execute instead this instruction before bfq_remove_request() ++ * (and hence introduce a temporary inconsistency), for efficiency. ++ * In fact, in a forced_dispatch, this prevents two counters related ++ * to bfqq->dispatched to risk to be uselessly decremented if bfqq ++ * is not in service, and then to be incremented again after ++ * incrementing bfqq->dispatched. ++ */ ++ bfqq->dispatched++; ++ bfq_update_peak_rate(q->elevator->elevator_data, rq); ++ ++ bfq_remove_request(rq); ++ elv_dispatch_sort(q, rq); ++} ++ ++static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* ++ * If this bfqq is shared between multiple processes, check ++ * to make sure that those processes are still issuing I/Os ++ * within the mean seek distance. If not, it may be time to ++ * break the queues apart again. ++ */ ++ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq)) ++ bfq_mark_bfqq_split_coop(bfqq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ if (bfqq->dispatched == 0) ++ /* ++ * Overloading budget_timeout field to store ++ * the time at which the queue remains with no ++ * backlog and no outstanding request; used by ++ * the weight-raising mechanism. ++ */ ++ bfqq->budget_timeout = jiffies; ++ ++ bfq_del_bfqq_busy(bfqd, bfqq, true); ++ } else { ++ bfq_requeue_bfqq(bfqd, bfqq, true); ++ /* ++ * Resort priority tree of potential close cooperators. ++ */ ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } ++ ++ /* ++ * All in-service entities must have been properly deactivated ++ * or requeued before executing the next function, which ++ * resets all in-service entites as no more in service. ++ */ ++ __bfq_bfqd_reset_in_service(bfqd); ++} ++ ++/** ++ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior. ++ * @bfqd: device data. ++ * @bfqq: queue to update. ++ * @reason: reason for expiration. ++ * ++ * Handle the feedback on @bfqq budget at queue expiration. ++ * See the body for detailed comments. ++ */ ++static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ enum bfqq_expiration reason) ++{ ++ struct request *next_rq; ++ int budget, min_budget; ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ min_budget = bfq_min_budget(bfqd); ++ ++ if (bfqq->wr_coeff == 1) ++ budget = bfqq->max_budget; ++ else /* ++ * Use a constant, low budget for weight-raised queues, ++ * to help achieve a low latency. Keep it slightly higher ++ * than the minimum possible budget, to cause a little ++ * bit fewer expirations. ++ */ ++ budget = 2 * min_budget; ++ ++ bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d", ++ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); ++ bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d", ++ budget, bfq_min_budget(bfqd)); ++ bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d", ++ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); ++ ++ if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) { ++ switch (reason) { ++ /* ++ * Caveat: in all the following cases we trade latency ++ * for throughput. ++ */ ++ case BFQ_BFQQ_TOO_IDLE: ++ /* ++ * This is the only case where we may reduce ++ * the budget: if there is no request of the ++ * process still waiting for completion, then ++ * we assume (tentatively) that the timer has ++ * expired because the batch of requests of ++ * the process could have been served with a ++ * smaller budget. Hence, betting that ++ * process will behave in the same way when it ++ * becomes backlogged again, we reduce its ++ * next budget. As long as we guess right, ++ * this budget cut reduces the latency ++ * experienced by the process. ++ * ++ * However, if there are still outstanding ++ * requests, then the process may have not yet ++ * issued its next request just because it is ++ * still waiting for the completion of some of ++ * the still outstanding ones. So in this ++ * subcase we do not reduce its budget, on the ++ * contrary we increase it to possibly boost ++ * the throughput, as discussed in the ++ * comments to the BUDGET_TIMEOUT case. ++ */ ++ if (bfqq->dispatched > 0) /* still outstanding reqs */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ else { ++ if (budget > 5 * min_budget) ++ budget -= 4 * min_budget; ++ else ++ budget = min_budget; ++ } ++ break; ++ case BFQ_BFQQ_BUDGET_TIMEOUT: ++ /* ++ * We double the budget here because it gives ++ * the chance to boost the throughput if this ++ * is not a seeky process (and has bumped into ++ * this timeout because of, e.g., ZBR). ++ */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_BUDGET_EXHAUSTED: ++ /* ++ * The process still has backlog, and did not ++ * let either the budget timeout or the disk ++ * idling timeout expire. Hence it is not ++ * seeky, has a short thinktime and may be ++ * happy with a higher budget too. So ++ * definitely increase the budget of this good ++ * candidate to boost the disk throughput. ++ */ ++ budget = min(budget * 4, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_NO_MORE_REQUESTS: ++ /* ++ * For queues that expire for this reason, it ++ * is particularly important to keep the ++ * budget close to the actual service they ++ * need. Doing so reduces the timestamp ++ * misalignment problem described in the ++ * comments in the body of ++ * __bfq_activate_entity. In fact, suppose ++ * that a queue systematically expires for ++ * BFQ_BFQQ_NO_MORE_REQUESTS and presents a ++ * new request in time to enjoy timestamp ++ * back-shifting. The larger the budget of the ++ * queue is with respect to the service the ++ * queue actually requests in each service ++ * slot, the more times the queue can be ++ * reactivated with the same virtual finish ++ * time. It follows that, even if this finish ++ * time is pushed to the system virtual time ++ * to reduce the consequent timestamp ++ * misalignment, the queue unjustly enjoys for ++ * many re-activations a lower finish time ++ * than all newly activated queues. ++ * ++ * The service needed by bfqq is measured ++ * quite precisely by bfqq->entity.service. ++ * Since bfqq does not enjoy device idling, ++ * bfqq->entity.service is equal to the number ++ * of sectors that the process associated with ++ * bfqq requested to read/write before waiting ++ * for request completions, or blocking for ++ * other reasons. ++ */ ++ budget = max_t(int, bfqq->entity.service, min_budget); ++ break; ++ default: ++ return; ++ } ++ } else if (!bfq_bfqq_sync(bfqq)) ++ /* ++ * Async queues get always the maximum possible ++ * budget, as for them we do not care about latency ++ * (in addition, their ability to dispatch is limited ++ * by the charging factor). ++ */ ++ budget = bfqd->bfq_max_budget; ++ ++ bfqq->max_budget = budget; ++ ++ if (bfqd->budgets_assigned >= bfq_stats_min_budgets && ++ !bfqd->bfq_user_max_budget) ++ bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); ++ ++ /* ++ * If there is still backlog, then assign a new budget, making ++ * sure that it is large enough for the next request. Since ++ * the finish time of bfqq must be kept in sync with the ++ * budget, be sure to call __bfq_bfqq_expire() *after* this ++ * update. ++ * ++ * If there is no backlog, then no need to update the budget; ++ * it will be updated on the arrival of a new request. ++ */ ++ next_rq = bfqq->next_rq; ++ if (next_rq) { ++ BUG_ON(reason == BFQ_BFQQ_TOO_IDLE || ++ reason == BFQ_BFQQ_NO_MORE_REQUESTS); ++ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", ++ next_rq ? blk_rq_sectors(next_rq) : 0, ++ bfqq->entity.budget); ++} ++ ++/* ++ * Return true if the process associated with bfqq is "slow". The slow ++ * flag is used, in addition to the budget timeout, to reduce the ++ * amount of service provided to seeky processes, and thus reduce ++ * their chances to lower the throughput. More details in the comments ++ * on the function bfq_bfqq_expire(). ++ * ++ * An important observation is in order: as discussed in the comments ++ * on the function bfq_update_peak_rate(), with devices with internal ++ * queues, it is hard if ever possible to know when and for how long ++ * an I/O request is processed by the device (apart from the trivial ++ * I/O pattern where a new request is dispatched only after the ++ * previous one has been completed). This makes it hard to evaluate ++ * the real rate at which the I/O requests of each bfq_queue are ++ * served. In fact, for an I/O scheduler like BFQ, serving a ++ * bfq_queue means just dispatching its requests during its service ++ * slot (i.e., until the budget of the queue is exhausted, or the ++ * queue remains idle, or, finally, a timeout fires). But, during the ++ * service slot of a bfq_queue, around 100 ms at most, the device may ++ * be even still processing requests of bfq_queues served in previous ++ * service slots. On the opposite end, the requests of the in-service ++ * bfq_queue may be completed after the service slot of the queue ++ * finishes. ++ * ++ * Anyway, unless more sophisticated solutions are used ++ * (where possible), the sum of the sizes of the requests dispatched ++ * during the service slot of a bfq_queue is probably the only ++ * approximation available for the service received by the bfq_queue ++ * during its service slot. And this sum is the quantity used in this ++ * function to evaluate the I/O speed of a process. ++ */ ++static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool compensate, enum bfqq_expiration reason, ++ unsigned long *delta_ms) ++{ ++ ktime_t delta_ktime; ++ u32 delta_usecs; ++ bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */ ++ ++ if (!bfq_bfqq_sync(bfqq)) ++ return false; ++ ++ if (compensate) ++ delta_ktime = bfqd->last_idling_start; ++ else ++ delta_ktime = ktime_get(); ++ delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start); ++ delta_usecs = ktime_to_us(delta_ktime); ++ ++ /* don't use too short time intervals */ ++ if (delta_usecs < 1000) { ++ if (blk_queue_nonrot(bfqd->queue)) ++ /* ++ * give same worst-case guarantees as idling ++ * for seeky ++ */ ++ *delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC; ++ else /* charge at least one seek */ ++ *delta_ms = bfq_slice_idle / NSEC_PER_MSEC; ++ ++ bfq_log(bfqd, "too short %u", delta_usecs); ++ ++ return slow; ++ } ++ ++ *delta_ms = delta_usecs / USEC_PER_MSEC; ++ ++ /* ++ * Use only long (> 20ms) intervals to filter out excessive ++ * spikes in service rate estimation. ++ */ ++ if (delta_usecs > 20000) { ++ /* ++ * Caveat for rotational devices: processes doing I/O ++ * in the slower disk zones tend to be slow(er) even ++ * if not seeky. In this respect, the estimated peak ++ * rate is likely to be an average over the disk ++ * surface. Accordingly, to not be too harsh with ++ * unlucky processes, a process is deemed slow only if ++ * its rate has been lower than half of the estimated ++ * peak rate. ++ */ ++ slow = bfqq->entity.service < bfqd->bfq_max_budget / 2; ++ bfq_log(bfqd, "relative rate %d/%d", ++ bfqq->entity.service, bfqd->bfq_max_budget); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "slow %d", slow); ++ ++ return slow; ++} ++ ++/* ++ * To be deemed as soft real-time, an application must meet two ++ * requirements. First, the application must not require an average ++ * bandwidth higher than the approximate bandwidth required to playback or ++ * record a compressed high-definition video. ++ * The next function is invoked on the completion of the last request of a ++ * batch, to compute the next-start time instant, soft_rt_next_start, such ++ * that, if the next request of the application does not arrive before ++ * soft_rt_next_start, then the above requirement on the bandwidth is met. ++ * ++ * The second requirement is that the request pattern of the application is ++ * isochronous, i.e., that, after issuing a request or a batch of requests, ++ * the application stops issuing new requests until all its pending requests ++ * have been completed. After that, the application may issue a new batch, ++ * and so on. ++ * For this reason the next function is invoked to compute ++ * soft_rt_next_start only for applications that meet this requirement, ++ * whereas soft_rt_next_start is set to infinity for applications that do ++ * not. ++ * ++ * Unfortunately, even a greedy (i.e., I/O-bound) application may ++ * happen to meet, occasionally or systematically, both the above ++ * bandwidth and isochrony requirements. This may happen at least in ++ * the following circumstances. First, if the CPU load is high. The ++ * application may stop issuing requests while the CPUs are busy ++ * serving other processes, then restart, then stop again for a while, ++ * and so on. The other circumstances are related to the storage ++ * device: the storage device is highly loaded or reaches a low-enough ++ * throughput with the I/O of the application (e.g., because the I/O ++ * is random and/or the device is slow). In all these cases, the ++ * I/O of the application may be simply slowed down enough to meet ++ * the bandwidth and isochrony requirements. To reduce the probability ++ * that greedy applications are deemed as soft real-time in these ++ * corner cases, a further rule is used in the computation of ++ * soft_rt_next_start: the return value of this function is forced to ++ * be higher than the maximum between the following two quantities. ++ * ++ * (a) Current time plus: (1) the maximum time for which the arrival ++ * of a request is waited for when a sync queue becomes idle, ++ * namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We ++ * postpone for a moment the reason for adding a few extra ++ * jiffies; we get back to it after next item (b). Lower-bounding ++ * the return value of this function with the current time plus ++ * bfqd->bfq_slice_idle tends to filter out greedy applications, ++ * because the latter issue their next request as soon as possible ++ * after the last one has been completed. In contrast, a soft ++ * real-time application spends some time processing data, after a ++ * batch of its requests has been completed. ++ * ++ * (b) Current value of bfqq->soft_rt_next_start. As pointed out ++ * above, greedy applications may happen to meet both the ++ * bandwidth and isochrony requirements under heavy CPU or ++ * storage-device load. In more detail, in these scenarios, these ++ * applications happen, only for limited time periods, to do I/O ++ * slowly enough to meet all the requirements described so far, ++ * including the filtering in above item (a). These slow-speed ++ * time intervals are usually interspersed between other time ++ * intervals during which these applications do I/O at a very high ++ * speed. Fortunately, exactly because of the high speed of the ++ * I/O in the high-speed intervals, the values returned by this ++ * function happen to be so high, near the end of any such ++ * high-speed interval, to be likely to fall *after* the end of ++ * the low-speed time interval that follows. These high values are ++ * stored in bfqq->soft_rt_next_start after each invocation of ++ * this function. As a consequence, if the last value of ++ * bfqq->soft_rt_next_start is constantly used to lower-bound the ++ * next value that this function may return, then, from the very ++ * beginning of a low-speed interval, bfqq->soft_rt_next_start is ++ * likely to be constantly kept so high that any I/O request ++ * issued during the low-speed interval is considered as arriving ++ * to soon for the application to be deemed as soft ++ * real-time. Then, in the high-speed interval that follows, the ++ * application will not be deemed as soft real-time, just because ++ * it will do I/O at a high speed. And so on. ++ * ++ * Getting back to the filtering in item (a), in the following two ++ * cases this filtering might be easily passed by a greedy ++ * application, if the reference quantity was just ++ * bfqd->bfq_slice_idle: ++ * 1) HZ is so low that the duration of a jiffy is comparable to or ++ * higher than bfqd->bfq_slice_idle. This happens, e.g., on slow ++ * devices with HZ=100. The time granularity may be so coarse ++ * that the approximation, in jiffies, of bfqd->bfq_slice_idle ++ * is rather lower than the exact value. ++ * 2) jiffies, instead of increasing at a constant rate, may stop increasing ++ * for a while, then suddenly 'jump' by several units to recover the lost ++ * increments. This seems to happen, e.g., inside virtual machines. ++ * To address this issue, in the filtering in (a) we do not use as a ++ * reference time interval just bfqd->bfq_slice_idle, but ++ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the ++ * minimum number of jiffies for which the filter seems to be quite ++ * precise also in embedded systems and KVM/QEMU virtual machines. ++ */ ++static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, ++"service_blkg %lu soft_rate %u sects/sec interval %u", ++ bfqq->service_from_backlogged, ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies_to_msecs(HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate)); ++ ++ return max3(bfqq->soft_rt_next_start, ++ bfqq->last_idle_bklogged + ++ HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4); ++} ++ ++static bool bfq_bfqq_injectable(struct bfq_queue *bfqq) ++{ ++ return BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 && ++ blk_queue_nonrot(bfqq->bfqd->queue) && ++ bfqq->bfqd->hw_tag; ++} ++ ++/** ++ * bfq_bfqq_expire - expire a queue. ++ * @bfqd: device owning the queue. ++ * @bfqq: the queue to expire. ++ * @compensate: if true, compensate for the time spent idling. ++ * @reason: the reason causing the expiration. ++ * ++ * If the process associated with bfqq does slow I/O (e.g., because it ++ * issues random requests), we charge bfqq with the time it has been ++ * in service instead of the service it has received (see ++ * bfq_bfqq_charge_time for details on how this goal is achieved). As ++ * a consequence, bfqq will typically get higher timestamps upon ++ * reactivation, and hence it will be rescheduled as if it had ++ * received more service than what it has actually received. In the ++ * end, bfqq receives less service in proportion to how slowly its ++ * associated process consumes its budgets (and hence how seriously it ++ * tends to lower the throughput). In addition, this time-charging ++ * strategy guarantees time fairness among slow processes. In ++ * contrast, if the process associated with bfqq is not slow, we ++ * charge bfqq exactly with the service it has received. ++ * ++ * Charging time to the first type of queues and the exact service to ++ * the other has the effect of using the WF2Q+ policy to schedule the ++ * former on a timeslice basis, without violating service domain ++ * guarantees among the latter. ++ */ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason) ++{ ++ bool slow; ++ unsigned long delta = 0; ++ struct bfq_entity *entity = &bfqq->entity; ++ int ref; ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* ++ * Check whether the process is slow (see bfq_bfqq_is_slow). ++ */ ++ slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta); ++ ++ /* ++ * As above explained, charge slow (typically seeky) and ++ * timed-out queues with the time and not the service ++ * received, to favor sequential workloads. ++ * ++ * Processes doing I/O in the slower disk zones will tend to ++ * be slow(er) even if not seeky. Therefore, since the ++ * estimated peak rate is actually an average over the disk ++ * surface, these processes may timeout just for bad luck. To ++ * avoid punishing them, do not charge time to processes that ++ * succeeded in consuming at least 2/3 of their budget. This ++ * allows BFQ to preserve enough elasticity to still perform ++ * bandwidth, and not time, distribution with little unlucky ++ * or quasi-sequential processes. ++ */ ++ if (bfqq->wr_coeff == 1 && ++ (slow || ++ (reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ bfq_bfqq_budget_left(bfqq) >= entity->budget / 3))) ++ bfq_bfqq_charge_time(bfqd, bfqq, delta); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ if (reason == BFQ_BFQQ_TOO_IDLE && ++ entity->service <= 2 * entity->budget / 10) ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (bfqd->low_latency && bfqq->wr_coeff == 1) ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * If we get here, and there are no outstanding ++ * requests, then the request pattern is isochronous ++ * (see the comments on the function ++ * bfq_bfqq_softrt_next_start()). Thus we can compute ++ * soft_rt_next_start. And we do it, unless bfqq is in ++ * interactive weight raising. We do not do it in the ++ * latter subcase, for the following reason. bfqq may ++ * be conveying the I/O needed to load a soft ++ * real-time application. Such an application will ++ * actually exhibit a soft real-time I/O pattern after ++ * it finally starts doing its job. But, if ++ * soft_rt_next_start is computed here for an ++ * interactive bfqq, and bfqq had received a lot of ++ * service before remaining with no outstanding ++ * request (likely to happen on a fast device), then ++ * soft_rt_next_start would be assigned such a high ++ * value that, for a very long time, bfqq would be ++ * prevented from being possibly considered as soft ++ * real time. ++ * ++ * If, instead, the queue still has outstanding ++ * requests, then we have to wait for the completion ++ * of all the outstanding requests to discover whether ++ * the request pattern is actually isochronous. ++ */ ++ BUG_ON(bfq_tot_busy_queues(bfqd) < 1); ++ if (bfqq->dispatched == 0 && ++ bfqq->wr_coeff != bfqd->bfq_wr_coeff) { ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu", ++ bfqq->soft_rt_next_start); ++ } else if (bfqq->dispatched > 0) { ++ /* ++ * Schedule an update of soft_rt_next_start to when ++ * the task may be discovered to be isochronous. ++ */ ++ bfq_mark_bfqq_softrt_update(bfqq); ++ } ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "expire (%s, slow %d, num_disp %d, short %d, weight %d, serv %d/%d)", ++ reason_name[reason], slow, bfqq->dispatched, ++ bfq_bfqq_has_short_ttime(bfqq), entity->weight, ++ entity->service, entity->budget); ++ ++ /* ++ * Increase, decrease or leave budget unchanged according to ++ * reason. ++ */ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); ++ BUG_ON(bfqq->next_rq == NULL && ++ bfqq->entity.budget < bfqq->entity.service); ++ ref = bfqq->ref; ++ __bfq_bfqq_expire(bfqd, bfqq); ++ ++ if (ref == 1) /* bfqq is gone, no more actions on it */ ++ return; ++ ++ BUG_ON(ref > 1 && ++ !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED && ++ !bfq_class_idle(bfqq)); ++ ++ bfqq->injected_service = 0; ++ ++ /* mark bfqq as waiting a request only if a bic still points to it */ ++ if (!bfq_bfqq_busy(bfqq) && ++ reason != BFQ_BFQQ_BUDGET_TIMEOUT && ++ reason != BFQ_BFQQ_BUDGET_EXHAUSTED) { ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(bfqq->next_rq); ++ bfq_mark_bfqq_non_blocking_wait_rq(bfqq); ++ /* ++ * Not setting service to 0, because, if the next rq ++ * arrives in time, the queue will go on receiving ++ * service with this same budget (as if it never expired) ++ */ ++ } else { ++ entity->service = 0; ++ bfq_log_bfqq(bfqd, bfqq, "resetting service"); ++ } ++ ++ /* ++ * Reset the received-service counter for every parent entity. ++ * Differently from what happens with bfqq->entity.service, ++ * the resetting of this counter never needs to be postponed ++ * for parent entities. In fact, in case bfqq may have a ++ * chance to go on being served using the last, partially ++ * consumed budget, bfqq->entity.service needs to be kept, ++ * because if bfqq then actually goes on being served using ++ * the same budget, the last value of bfqq->entity.service is ++ * needed to properly decrement bfqq->entity.budget by the ++ * portion already consumed. In contrast, it is not necessary ++ * to keep entity->service for parent entities too, because ++ * the bubble up of the new value of bfqq->entity.budget will ++ * make sure that the budgets of parent entities are correct, ++ * even in case bfqq and thus parent entities go on receiving ++ * service with the same budget. ++ */ ++ entity = entity->parent; ++ for_each_entity(entity) ++ entity->service = 0; ++} ++ ++/* ++ * Budget timeout is not implemented through a dedicated timer, but ++ * just checked on request arrivals and completions, as well as on ++ * idle timer expirations. ++ */ ++static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) ++{ ++ return time_is_before_eq_jiffies(bfqq->budget_timeout); ++} ++ ++/* ++ * If we expire a queue that is actively waiting (i.e., with the ++ * device idled) for the arrival of a new request, then we may incur ++ * the timestamp misalignment problem described in the body of the ++ * function __bfq_activate_entity. Hence we return true only if this ++ * condition does not hold, or if the queue is slow enough to deserve ++ * only to be kicked off for preserving a high throughput. ++ */ ++static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "wait_request %d left %d timeout %d", ++ bfq_bfqq_wait_request(bfqq), ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3, ++ bfq_bfqq_budget_timeout(bfqq)); ++ ++ return (!bfq_bfqq_wait_request(bfqq) || ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3) ++ && ++ bfq_bfqq_budget_timeout(bfqq); ++} ++ ++static bool idling_boosts_thr_without_issues(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bool rot_without_queueing = ++ !blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag, ++ bfqq_sequential_and_IO_bound, ++ idling_boosts_thr; ++ ++ bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) && ++ bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq); ++ /* ++ * The next variable takes into account the cases where idling ++ * boosts the throughput. ++ * ++ * The value of the variable is computed considering, first, that ++ * idling is virtually always beneficial for the throughput if: ++ * (a) the device is not NCQ-capable and rotational, or ++ * (b) regardless of the presence of NCQ, the device is rotational and ++ * the request pattern for bfqq is I/O-bound and sequential, or ++ * (c) regardless of whether it is rotational, the device is ++ * not NCQ-capable and the request pattern for bfqq is ++ * I/O-bound and sequential. ++ * ++ * Secondly, and in contrast to the above item (b), idling an ++ * NCQ-capable flash-based device would not boost the ++ * throughput even with sequential I/O; rather it would lower ++ * the throughput in proportion to how fast the device ++ * is. Accordingly, the next variable is true if any of the ++ * above conditions (a), (b) or (c) is true, and, in ++ * particular, happens to be false if bfqd is an NCQ-capable ++ * flash-based device. ++ */ ++ idling_boosts_thr = rot_without_queueing || ++ ((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) && ++ bfqq_sequential_and_IO_bound); ++ ++ bfq_log_bfqq(bfqd, bfqq, "idling_boosts_thr %d", idling_boosts_thr); ++ ++ /* ++ * The return value of this function is equal to that of ++ * idling_boosts_thr, unless a special case holds. In this ++ * special case, described below, idling may cause problems to ++ * weight-raised queues. ++ * ++ * When the request pool is saturated (e.g., in the presence ++ * of write hogs), if the processes associated with ++ * non-weight-raised queues ask for requests at a lower rate, ++ * then processes associated with weight-raised queues have a ++ * higher probability to get a request from the pool ++ * immediately (or at least soon) when they need one. Thus ++ * they have a higher probability to actually get a fraction ++ * of the device throughput proportional to their high ++ * weight. This is especially true with NCQ-capable drives, ++ * which enqueue several requests in advance, and further ++ * reorder internally-queued requests. ++ * ++ * For this reason, we force to false the return value if ++ * there are weight-raised busy queues. In this case, and if ++ * bfqq is not weight-raised, this guarantees that the device ++ * is not idled for bfqq (if, instead, bfqq is weight-raised, ++ * then idling will be guaranteed by another variable, see ++ * below). Combined with the timestamping rules of BFQ (see ++ * [1] for details), this behavior causes bfqq, and hence any ++ * sync non-weight-raised queue, to get a lower number of ++ * requests served, and thus to ask for a lower number of ++ * requests from the request pool, before the busy ++ * weight-raised queues get served again. This often mitigates ++ * starvation problems in the presence of heavy write ++ * workloads and NCQ, thereby guaranteeing a higher ++ * application and system responsiveness in these hostile ++ * scenarios. ++ */ ++ return idling_boosts_thr && ++ bfqd->wr_busy_queues == 0; ++} ++ ++/* ++ * There is a case where idling must be performed not for ++ * throughput concerns, but to preserve service guarantees. ++ * ++ * To introduce this case, we can note that allowing the drive ++ * to enqueue more than one request at a time, and hence ++ * delegating de facto final scheduling decisions to the ++ * drive's internal scheduler, entails loss of control on the ++ * actual request service order. In particular, the critical ++ * situation is when requests from different processes happen ++ * to be present, at the same time, in the internal queue(s) ++ * of the drive. In such a situation, the drive, by deciding ++ * the service order of the internally-queued requests, does ++ * determine also the actual throughput distribution among ++ * these processes. But the drive typically has no notion or ++ * concern about per-process throughput distribution, and ++ * makes its decisions only on a per-request basis. Therefore, ++ * the service distribution enforced by the drive's internal ++ * scheduler is likely to coincide with the desired ++ * device-throughput distribution only in a completely ++ * symmetric scenario where: ++ * (i) each of these processes must get the same throughput as ++ * the others; ++ * (ii) the I/O of each process has the same properties, in ++ * terms of locality (sequential or random), direction ++ * (reads or writes), request sizes, greediness ++ * (from I/O-bound to sporadic), and so on. ++ * In fact, in such a scenario, the drive tends to treat ++ * the requests of each of these processes in about the same ++ * way as the requests of the others, and thus to provide ++ * each of these processes with about the same throughput ++ * (which is exactly the desired throughput distribution). In ++ * contrast, in any asymmetric scenario, device idling is ++ * certainly needed to guarantee that bfqq receives its ++ * assigned fraction of the device throughput (see [1] for ++ * details). ++ * The problem is that idling may significantly reduce ++ * throughput with certain combinations of types of I/O and ++ * devices. An important example is sync random I/O, on flash ++ * storage with command queueing. So, unless bfqq falls in the ++ * above cases where idling also boosts throughput, it would ++ * be important to check conditions (i) and (ii) accurately, ++ * so as to avoid idling when not strictly needed for service ++ * guarantees. ++ * ++ * Unfortunately, it is extremely difficult to thoroughly ++ * check condition (ii). And, in case there are active groups, ++ * it becomes very difficult to check condition (i) too. In ++ * fact, if there are active groups, then, for condition (i) ++ * to become false, it is enough that an active group contains ++ * more active processes or sub-groups than some other active ++ * group. More precisely, for condition (i) to hold because of ++ * such a group, it is not even necessary that the group is ++ * (still) active: it is sufficient that, even if the group ++ * has become inactive, some of its descendant processes still ++ * have some request already dispatched but still waiting for ++ * completion. In fact, requests have still to be guaranteed ++ * their share of the throughput even after being ++ * dispatched. In this respect, it is easy to show that, if a ++ * group frequently becomes inactive while still having ++ * in-flight requests, and if, when this happens, the group is ++ * not considered in the calculation of whether the scenario ++ * is asymmetric, then the group may fail to be guaranteed its ++ * fair share of the throughput (basically because idling may ++ * not be performed for the descendant processes of the group, ++ * but it had to be). We address this issue with the ++ * following bi-modal behavior, implemented in the function ++ * bfq_symmetric_scenario(). ++ * ++ * If there are groups with requests waiting for completion ++ * (as commented above, some of these groups may even be ++ * already inactive), then the scenario is tagged as ++ * asymmetric, conservatively, without checking any of the ++ * conditions (i) and (ii). So the device is idled for bfqq. ++ * This behavior matches also the fact that groups are created ++ * exactly if controlling I/O is a primary concern (to ++ * preserve bandwidth and latency guarantees). ++ * ++ * On the opposite end, if there are no groups with requests ++ * waiting for completion, then only condition (i) is actually ++ * controlled, i.e., provided that condition (i) holds, idling ++ * is not performed, regardless of whether condition (ii) ++ * holds. In other words, only if condition (i) does not hold, ++ * then idling is allowed, and the device tends to be ++ * prevented from queueing many requests, possibly of several ++ * processes. Since there are no groups with requests waiting ++ * for completion, then, to control condition (i) it is enough ++ * to check just whether all the queues with requests waiting ++ * for completion also have the same weight. ++ * ++ * Not checking condition (ii) evidently exposes bfqq to the ++ * risk of getting less throughput than its fair share. ++ * However, for queues with the same weight, a further ++ * mechanism, preemption, mitigates or even eliminates this ++ * problem. And it does so without consequences on overall ++ * throughput. This mechanism and its benefits are explained ++ * in the next three paragraphs. ++ * ++ * Even if a queue, say Q, is expired when it remains idle, Q ++ * can still preempt the new in-service queue if the next ++ * request of Q arrives soon (see the comments on ++ * bfq_bfqq_update_budg_for_activation). If all queues and ++ * groups have the same weight, this form of preemption, ++ * combined with the hole-recovery heuristic described in the ++ * comments on function bfq_bfqq_update_budg_for_activation, ++ * are enough to preserve a correct bandwidth distribution in ++ * the mid term, even without idling. In fact, even if not ++ * idling allows the internal queues of the device to contain ++ * many requests, and thus to reorder requests, we can rather ++ * safely assume that the internal scheduler still preserves a ++ * minimum of mid-term fairness. ++ * ++ * More precisely, this preemption-based, idleless approach ++ * provides fairness in terms of IOPS, and not sectors per ++ * second. This can be seen with a simple example. Suppose ++ * that there are two queues with the same weight, but that ++ * the first queue receives requests of 8 sectors, while the ++ * second queue receives requests of 1024 sectors. In ++ * addition, suppose that each of the two queues contains at ++ * most one request at a time, which implies that each queue ++ * always remains idle after it is served. Finally, after ++ * remaining idle, each queue receives very quickly a new ++ * request. It follows that the two queues are served ++ * alternatively, preempting each other if needed. This ++ * implies that, although both queues have the same weight, ++ * the queue with large requests receives a service that is ++ * 1024/8 times as high as the service received by the other ++ * queue. ++ * ++ * The motivation for using preemption instead of idling (for ++ * queues with the same weight) is that, by not idling, ++ * service guarantees are preserved (completely or at least in ++ * part) without minimally sacrificing throughput. And, if ++ * there is no active group, then the primary expectation for ++ * this device is probably a high throughput. ++ * ++ * We are now left only with explaining the additional ++ * compound condition that is checked below for deciding ++ * whether the scenario is asymmetric. To explain this ++ * compound condition, we need to add that the function ++ * bfq_symmetric_scenario checks the weights of only ++ * non-weight-raised queues, for efficiency reasons (see ++ * comments on bfq_weights_tree_add()). Then the fact that ++ * bfqq is weight-raised is checked explicitly here. More ++ * precisely, the compound condition below takes into account ++ * also the fact that, even if bfqq is being weight-raised, ++ * the scenario is still symmetric if all queues with requests ++ * waiting for completion happen to be ++ * weight-raised. Actually, we should be even more precise ++ * here, and differentiate between interactive weight raising ++ * and soft real-time weight raising. ++ * ++ * As a side note, it is worth considering that the above ++ * device-idling countermeasures may however fail in the ++ * following unlucky scenario: if idling is (correctly) ++ * disabled in a time period during which all symmetry ++ * sub-conditions hold, and hence the device is allowed to ++ * enqueue many requests, but at some later point in time some ++ * sub-condition stops to hold, then it may become impossible ++ * to let requests be served in the desired order until all ++ * the requests already queued in the device have been served. ++ */ ++static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ bool asymmetric_scenario = (bfqq->wr_coeff > 1 && ++ bfqd->wr_busy_queues < ++ bfq_tot_busy_queues(bfqd)) || ++ !bfq_symmetric_scenario(bfqd); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wr_coeff %d wr_busy %d busy %d asymmetric %d", ++ bfqq->wr_coeff, ++ bfqd->wr_busy_queues, ++ bfq_tot_busy_queues(bfqd), ++ asymmetric_scenario); ++ ++ return asymmetric_scenario; ++} ++ ++/* ++ * For a queue that becomes empty, device idling is allowed only if ++ * this function returns true for that queue. As a consequence, since ++ * device idling plays a critical role for both throughput boosting ++ * and service guarantees, the return value of this function plays a ++ * critical role as well. ++ * ++ * In a nutshell, this function returns true only if idling is ++ * beneficial for throughput or, even if detrimental for throughput, ++ * idling is however necessary to preserve service guarantees (low ++ * latency, desired throughput distribution, ...). In particular, on ++ * NCQ-capable devices, this function tries to return false, so as to ++ * help keep the drives' internal queues full, whenever this helps the ++ * device boost the throughput without causing any service-guarantee ++ * issue. ++ * ++ * Most of the issues taken into account to get the return value of ++ * this function are not trivial. We discuss these issues in the two ++ * functions providing the main pieces of information needed by this ++ * function. ++ */ ++static bool bfq_better_to_idle(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ bool idling_boosts_thr_with_no_issue, idling_needed_for_service_guar; ++ ++ if (unlikely(bfqd->strict_guarantees)) ++ return true; ++ ++ /* ++ * Idling is performed only if slice_idle > 0. In addition, we ++ * do not idle if ++ * (a) bfqq is async ++ * (b) bfqq is in the idle io prio class: in this case we do ++ * not idle because we want to minimize the bandwidth that ++ * queues in this class can steal to higher-priority queues ++ */ ++ if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) || ++ bfq_class_idle(bfqq)) ++ return false; ++ ++ idling_boosts_thr_with_no_issue = ++ idling_boosts_thr_without_issues(bfqd, bfqq); ++ ++ idling_needed_for_service_guar = ++ idling_needed_for_service_guarantees(bfqd, bfqq); ++ ++ /* ++ * We have now the two components we need to compute the ++ * return value of the function, which is true only if idling ++ * either boosts the throughput (without issues), or is ++ * necessary to preserve service guarantees. ++ */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wr_busy %d boosts %d IO-bound %d guar %d", ++ bfqd->wr_busy_queues, ++ idling_boosts_thr_with_no_issue, ++ bfq_bfqq_IO_bound(bfqq), ++ idling_needed_for_service_guar); ++ ++ return idling_boosts_thr_with_no_issue || ++ idling_needed_for_service_guar; ++} ++ ++/* ++ * If the in-service queue is empty but the function bfq_better_to_idle ++ * returns true, then: ++ * 1) the queue must remain in service and cannot be expired, and ++ * 2) the device must be idled to wait for the possible arrival of a new ++ * request for the queue. ++ * See the comments on the function bfq_better_to_idle for the reasons ++ * why performing device idling is the best choice to boost the throughput ++ * and preserve service guarantees when bfq_better_to_idle itself ++ * returns true. ++ */ ++static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) ++{ ++ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq); ++} ++ ++static struct bfq_queue *bfq_choose_bfqq_for_injection(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ /* ++ * A linear search; but, with a high probability, very few ++ * steps are needed to find a candidate queue, i.e., a queue ++ * with enough budget left for its next request. In fact: ++ * - BFQ dynamically updates the budget of every queue so as ++ * to accomodate the expected backlog of the queue; ++ * - if a queue gets all its requests dispatched as injected ++ * service, then the queue is removed from the active list ++ * (and re-added only if it gets new requests, but with ++ * enough budget for its new backlog). ++ */ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ if (!RB_EMPTY_ROOT(&bfqq->sort_list) && ++ bfq_serv_to_charge(bfqq->next_rq, bfqq) <= ++ bfq_bfqq_budget_left(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, "returned this queue"); ++ return bfqq; ++ } ++ ++ bfq_log(bfqd, "no queue found"); ++ return NULL; ++} ++ ++/* ++ * Select a queue for service. If we have a current queue in service, ++ * check whether to continue servicing it, or retrieve and set a new one. ++ */ ++static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ struct request *next_rq; ++ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ ++ bfqq = bfqd->in_service_queue; ++ if (!bfqq) ++ goto new_queue; ++ ++ bfq_log_bfqq(bfqd, bfqq, "already in-service queue"); ++ ++ /* ++ * Do not expire bfqq for budget timeout if bfqq may be about ++ * to enjoy device idling. The reason why, in this case, we ++ * prevent bfqq from expiring is the same as in the comments ++ * on the case where bfq_bfqq_must_idle() returns true, in ++ * bfq_completed_request(). ++ */ ++ if (bfq_may_expire_for_budg_timeout(bfqq) && ++ !bfq_bfqq_must_idle(bfqq)) ++ goto expire; ++ ++check_queue: ++ /* ++ * This loop is rarely executed more than once. Even when it ++ * happens, it is much more convenient to re-execute this loop ++ * than to return NULL and trigger a new dispatch to get a ++ * request served. ++ */ ++ next_rq = bfqq->next_rq; ++ /* ++ * If bfqq has requests queued and it has enough budget left to ++ * serve them, keep the queue, otherwise expire it. ++ */ ++ if (next_rq) { ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ if (bfq_serv_to_charge(next_rq, bfqq) > ++ bfq_bfqq_budget_left(bfqq)) { ++ /* ++ * Expire the queue for budget exhaustion, ++ * which makes sure that the next budget is ++ * enough to serve the next request, even if ++ * it comes from the fifo expired path. ++ */ ++ reason = BFQ_BFQQ_BUDGET_EXHAUSTED; ++ goto expire; ++ } else { ++ /* ++ * The idle timer may be pending because we may ++ * not disable disk idling even when a new request ++ * arrives. ++ */ ++ if (bfq_bfqq_wait_request(bfqq)) { ++ BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer)); ++ /* ++ * If we get here: 1) at least a new request ++ * has arrived but we have not disabled the ++ * timer because the request was too small, ++ * 2) then the block layer has unplugged ++ * the device, causing the dispatch to be ++ * invoked. ++ * ++ * Since the device is unplugged, now the ++ * requests are probably large enough to ++ * provide a reasonable throughput. ++ * So we disable idling. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ hrtimer_try_to_cancel(&bfqd->idle_slice_timer); ++ bfqg_stats_update_idle_time(bfqq_group(bfqq)); ++ } ++ goto keep_queue; ++ } ++ } ++ ++ /* ++ * No requests pending. However, if the in-service queue is idling ++ * for a new request, or has requests waiting for a completion and ++ * may idle after their completion, then keep it anyway. ++ * ++ * Yet, to boost throughput, inject service from other queues if ++ * possible. ++ */ ++ if (hrtimer_active(&bfqd->idle_slice_timer) || ++ (bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) { ++ if (bfq_bfqq_injectable(bfqq) && ++ bfqq->injected_service * bfqq->inject_coeff < ++ bfqq->entity.service * 10) { ++ bfq_log_bfqq(bfqd, bfqq, "looking for queue for injection"); ++ bfqq = bfq_choose_bfqq_for_injection(bfqd); ++ } else { ++ if (BFQQ_SEEKY(bfqq)) ++ bfq_log_bfqq(bfqd, bfqq, ++ "injection saturated %d * %d >= %d * 10", ++ bfqq->injected_service, bfqq->inject_coeff, ++ bfqq->entity.service); ++ bfqq = NULL; ++ } ++ goto keep_queue; ++ } ++ ++ reason = BFQ_BFQQ_NO_MORE_REQUESTS; ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, false, reason); ++new_queue: ++ bfqq = bfq_set_in_service_queue(bfqd); ++ if (bfqq) { ++ bfq_log_bfqq(bfqd, bfqq, "checking new queue"); ++ goto check_queue; ++ } ++keep_queue: ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, "returned this queue"); ++ else ++ bfq_log(bfqd, "no queue returned"); ++ ++ return bfqq; ++} ++ ++static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */ ++ BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ time_is_after_jiffies(bfqq->last_wr_start_finish)); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight != ++ entity->orig_weight * bfqq->wr_coeff); ++ if (entity->prio_changed) ++ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); ++ ++ /* ++ * If the queue was activated in a burst, or too much ++ * time has elapsed from the beginning of this ++ * weight-raising period, then end weight raising. ++ */ ++ if (bfq_bfqq_in_large_burst(bfqq)) ++ bfq_bfqq_end_wr(bfqq); ++ else if (time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time)) { ++ if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time || ++ time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt + ++ bfq_wr_duration(bfqd))) ++ bfq_bfqq_end_wr(bfqq); ++ else { ++ switch_back_to_interactive_wr(bfqq, bfqd); ++ BUG_ON(time_is_after_jiffies( ++ bfqq->last_wr_start_finish)); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "back to interactive wr"); ++ } ++ } ++ if (bfqq->wr_coeff > 1 && ++ bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time && ++ bfqq->service_from_wr > max_service_from_wr) { ++ /* see comments on max_service_from_wr */ ++ bfq_bfqq_end_wr(bfqq); ++ bfq_log_bfqq(bfqd, bfqq, ++ "too much service"); ++ } ++ } ++ /* ++ * To improve latency (for this or other queues), immediately ++ * update weight both if it must be raised and if it must be ++ * lowered. Since, entity may be on some active tree here, and ++ * might have a pending change of its ioprio class, invoke ++ * next function with the last parameter unset (see the ++ * comments on the function). ++ */ ++ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1)) ++ __bfq_entity_update_weight_prio(bfq_entity_service_tree(entity), ++ entity, false); ++} ++ ++/* ++ * Dispatch one request from bfqq, moving it to the request queue ++ * dispatch list. ++ */ ++static int bfq_dispatch_request(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ struct request *rq = bfqq->next_rq; ++ unsigned long service_to_charge; ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(!rq); ++ service_to_charge = bfq_serv_to_charge(rq, bfqq); ++ ++ BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq)); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ bfq_bfqq_served(bfqq, service_to_charge); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ bfq_dispatch_insert(bfqd->queue, rq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "dispatched %u sec req (%llu), budg left %d, new disp_nr %d", ++ blk_rq_sectors(rq), ++ (unsigned long long) blk_rq_pos(rq), ++ bfq_bfqq_budget_left(bfqq), ++ bfqq->dispatched); ++ ++ dispatched++; ++ ++ if (bfqq != bfqd->in_service_queue) { ++ if (likely(bfqd->in_service_queue)) { ++ bfqd->in_service_queue->injected_service += ++ bfq_serv_to_charge(rq, bfqq); ++ bfq_log_bfqq(bfqd, bfqd->in_service_queue, ++ "injected_service increased to %d", ++ bfqd->in_service_queue->injected_service); ++ } ++ return dispatched; ++ } ++ ++ /* ++ * If weight raising has to terminate for bfqq, then next ++ * function causes an immediate update of bfqq's weight, ++ * without waiting for next activation. As a consequence, on ++ * expiration, bfqq will be timestamped as if has never been ++ * weight-raised during this service slot, even if it has ++ * received part or even most of the service as a ++ * weight-raised queue. This inflates bfqq's timestamps, which ++ * is beneficial, as bfqq is then more willing to leave the ++ * device immediately to possible other weight-raised queues. ++ */ ++ bfq_update_wr_data(bfqd, bfqq); ++ ++ if (!bfqd->in_service_bic) { ++ atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount); ++ bfqd->in_service_bic = RQ_BIC(rq); ++ BUG_ON(!bfqd->in_service_bic); ++ } ++ ++ if (bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq)) ++ goto expire; ++ ++ return dispatched; ++ ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED); ++ return dispatched; ++} ++ ++static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ ++ while (bfqq->next_rq) { ++ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq); ++ dispatched++; ++ } ++ ++ BUG_ON(!list_empty(&bfqq->fifo)); ++ return dispatched; ++} ++ ++/* ++ * Drain our current requests. ++ * Used for barriers and when switching io schedulers on-the-fly. ++ */ ++static int bfq_forced_dispatch(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq, *n; ++ struct bfq_service_tree *st; ++ int dispatched = 0; ++ ++ bfqq = bfqd->in_service_queue; ++ if (bfqq) ++ __bfq_bfqq_expire(bfqd, bfqq); ++ ++ /* ++ * Loop through classes, and be careful to leave the scheduler ++ * in a consistent state, as feedback mechanisms and vtime ++ * updates cannot be disabled during the process. ++ */ ++ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) { ++ st = bfq_entity_service_tree(&bfqq->entity); ++ ++ dispatched += __bfq_forced_dispatch_bfqq(bfqq); ++ ++ bfqq->max_budget = bfq_max_budget(bfqd); ++ bfq_forget_idle(st); ++ } ++ ++ BUG_ON(bfq_tot_busy_queues(bfqd) != 0); ++ ++ return dispatched; ++} ++ ++static int bfq_dispatch_requests(struct request_queue *q, int force) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq; ++ ++ bfq_log(bfqd, "%d busy queues", bfq_tot_busy_queues(bfqd)); ++ ++ if (bfq_tot_busy_queues(bfqd) == 0) ++ return 0; ++ ++ if (unlikely(force)) ++ return bfq_forced_dispatch(bfqd); ++ ++ /* ++ * Force device to serve one request at a time if ++ * strict_guarantees is true. Forcing this service scheme is ++ * currently the ONLY way to guarantee that the request ++ * service order enforced by the scheduler is respected by a ++ * queueing device. Otherwise the device is free even to make ++ * some unlucky request wait for as long as the device ++ * wishes. ++ * ++ * Of course, serving one request at at time may cause loss of ++ * throughput. ++ */ ++ if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0) ++ return 0; ++ ++ bfqq = bfq_select_queue(bfqd); ++ if (!bfqq) ++ return 0; ++ ++ BUG_ON(bfqq == bfqd->in_service_queue && ++ bfqq->entity.budget < bfqq->entity.service); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue && ++ bfq_bfqq_wait_request(bfqq)); ++ ++ if (!bfq_dispatch_request(bfqd, bfqq)) ++ return 0; ++ ++ bfq_log_bfqq(bfqd, bfqq, "%s request", ++ bfq_bfqq_sync(bfqq) ? "sync" : "async"); ++ ++ BUG_ON(bfqq->next_rq == NULL && ++ bfqq->entity.budget < bfqq->entity.service); ++ return 1; ++} ++ ++/* ++ * Task holds one reference to the queue, dropped when task exits. Each rq ++ * in-flight on this queue also holds a reference, dropped when rq is freed. ++ * ++ * Queue lock must be held here. Recall not to use bfqq after calling ++ * this function on it. ++ */ ++static void bfq_put_queue(struct bfq_queue *bfqq) ++{ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ struct bfq_group *bfqg = bfqq_group(bfqq); ++#endif ++ ++ BUG_ON(bfqq->ref <= 0); ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref); ++ bfqq->ref--; ++ if (bfqq->ref) ++ return; ++ ++ BUG_ON(rb_first(&bfqq->sort_list)); ++ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0); ++ BUG_ON(bfqq->entity.tree); ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ ++ if (!hlist_unhashed(&bfqq->burst_list_node)) { ++ hlist_del_init(&bfqq->burst_list_node); ++ /* ++ * Decrement also burst size after the removal, if the ++ * process associated with bfqq is exiting, and thus ++ * does not contribute to the burst any longer. This ++ * decrement helps filter out false positives of large ++ * bursts, when some short-lived process (often due to ++ * the execution of commands by some service) happens ++ * to start and exit while a complex application is ++ * starting, and thus spawning several processes that ++ * do I/O (and that *must not* be treated as a large ++ * burst, see comments on bfq_handle_burst). ++ * ++ * In particular, the decrement is performed only if: ++ * 1) bfqq is not a merged queue, because, if it is, ++ * then this free of bfqq is not triggered by the exit ++ * of the process bfqq is associated with, but exactly ++ * by the fact that bfqq has just been merged. ++ * 2) burst_size is greater than 0, to handle ++ * unbalanced decrements. Unbalanced decrements may ++ * happen in te following case: bfqq is inserted into ++ * the current burst list--without incrementing ++ * bust_size--because of a split, but the current ++ * burst list is not the burst list bfqq belonged to ++ * (see comments on the case of a split in ++ * bfq_set_request). ++ */ ++ if (bfqq->bic && bfqq->bfqd->burst_size > 0) ++ bfqq->bfqd->burst_size--; ++ } ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq); ++ ++ kmem_cache_free(bfq_pool, bfqq); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ bfqg_put(bfqg); ++#endif ++} ++ ++static void bfq_put_cooperator(struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *__bfqq, *next; ++ ++ /* ++ * If this queue was scheduled to merge with another queue, be ++ * sure to drop the reference taken on that queue (and others in ++ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs. ++ */ ++ __bfqq = bfqq->new_bfqq; ++ while (__bfqq) { ++ if (__bfqq == bfqq) ++ break; ++ next = __bfqq->new_bfqq; ++ bfq_put_queue(__bfqq); ++ __bfqq = next; ++ } ++} ++ ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ if (bfqq == bfqd->in_service_queue) { ++ __bfq_bfqq_expire(bfqd, bfqq); ++ bfq_schedule_dispatch(bfqd); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); /* release process reference */ ++} ++ ++static void bfq_init_icq(struct io_cq *icq) ++{ ++ icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32); ++} ++ ++static void bfq_exit_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ ++ if (bic_to_bfqq(bic, false)) { ++ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false)); ++ bic_set_bfqq(bic, NULL, false); ++ } ++ ++ if (bic_to_bfqq(bic, true)) { ++ /* ++ * If the bic is using a shared queue, put the reference ++ * taken on the io_context when the bic started using a ++ * shared bfq_queue. ++ */ ++ if (bfq_bfqq_coop(bic_to_bfqq(bic, true))) ++ put_io_context(icq->ioc); ++ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true)); ++ bic_set_bfqq(bic, NULL, true); ++ } ++} ++ ++/* ++ * Update the entity prio values; note that the new values will not ++ * be used until the next (re)activation. ++ */ ++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ struct task_struct *tsk = current; ++ int ioprio_class; ++ ++ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ switch (ioprio_class) { ++ default: ++ dev_err(bfqq->bfqd->queue->backing_dev_info->dev, ++ "bfq: bad prio class %d\n", ioprio_class); ++ case IOPRIO_CLASS_NONE: ++ /* ++ * No prio set, inherit CPU scheduling settings. ++ */ ++ bfqq->new_ioprio = task_nice_ioprio(tsk); ++ bfqq->new_ioprio_class = task_nice_ioclass(tsk); ++ break; ++ case IOPRIO_CLASS_RT: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_RT; ++ break; ++ case IOPRIO_CLASS_BE: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_BE; ++ break; ++ case IOPRIO_CLASS_IDLE: ++ bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE; ++ bfqq->new_ioprio = 7; ++ break; ++ } ++ ++ if (bfqq->new_ioprio >= IOPRIO_BE_NR) { ++ pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n", ++ bfqq->new_ioprio); ++ BUG(); ++ } ++ ++ bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); ++ bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "bic_class %d prio %d class %d", ++ ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class); ++} ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct bfq_queue *bfqq; ++ unsigned long uninitialized_var(flags); ++ int ioprio = bic->icq.ioc->ioprio; ++ ++ /* ++ * This condition may trigger on a newly created bic, be sure to ++ * drop the lock before returning. ++ */ ++ if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) ++ return; ++ ++ bic->ioprio = ioprio; ++ ++ bfqq = bic_to_bfqq(bic, false); ++ if (bfqq) { ++ /* release process reference on this queue */ ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic); ++ bic_set_bfqq(bic, bfqq, false); ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfqq %p %d", ++ bfqq, bfqq->ref); ++ } ++ ++ bfqq = bic_to_bfqq(bic, true); ++ if (bfqq) ++ bfq_set_next_ioprio_data(bfqq, bic); ++} ++ ++static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic, pid_t pid, int is_sync) ++{ ++ RB_CLEAR_NODE(&bfqq->entity.rb_node); ++ INIT_LIST_HEAD(&bfqq->fifo); ++ INIT_HLIST_NODE(&bfqq->burst_list_node); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); ++ ++ bfqq->ref = 0; ++ bfqq->bfqd = bfqd; ++ ++ if (bic) ++ bfq_set_next_ioprio_data(bfqq, bic); ++ ++ if (is_sync) { ++ /* ++ * No need to mark as has_short_ttime if in ++ * idle_class, because no device idling is performed ++ * for queues in idle class ++ */ ++ if (!bfq_class_idle(bfqq)) ++ /* tentatively mark as has_short_ttime */ ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ bfq_mark_bfqq_sync(bfqq); ++ bfq_mark_bfqq_just_created(bfqq); ++ /* ++ * Aggressively inject a lot of service: up to 90%. ++ * This coefficient remains constant during bfqq life, ++ * but this behavior might be changed, after enough ++ * testing and tuning. ++ */ ++ bfqq->inject_coeff = 1; ++ } else ++ bfq_clear_bfqq_sync(bfqq); ++ bfq_mark_bfqq_IO_bound(bfqq); ++ ++ /* Tentative initial value to trade off between thr and lat */ ++ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3; ++ bfqq->pid = pid; ++ ++ bfqq->wr_coeff = 1; ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now(); ++ bfqq->budget_timeout = bfq_smallest_from_now(); ++ bfqq->split_time = bfq_smallest_from_now(); ++ ++ /* ++ * To not forget the possibly high bandwidth consumed by a ++ * process/queue in the recent past, ++ * bfq_bfqq_softrt_next_start() returns a value at least equal ++ * to the current value of bfqq->soft_rt_next_start (see ++ * comments on bfq_bfqq_softrt_next_start). Set ++ * soft_rt_next_start to now, to mean that bfqq has consumed ++ * no bandwidth so far. ++ */ ++ bfqq->soft_rt_next_start = jiffies; ++ ++ /* first request is almost certainly seeky */ ++ bfqq->seek_history = 1; ++} ++ ++static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ int ioprio_class, int ioprio) ++{ ++ switch (ioprio_class) { ++ case IOPRIO_CLASS_RT: ++ return &bfqg->async_bfqq[0][ioprio]; ++ case IOPRIO_CLASS_NONE: ++ ioprio = IOPRIO_NORM; ++ /* fall through */ ++ case IOPRIO_CLASS_BE: ++ return &bfqg->async_bfqq[1][ioprio]; ++ case IOPRIO_CLASS_IDLE: ++ return &bfqg->async_idle_bfqq; ++ default: ++ BUG(); ++ } ++} ++ ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic) ++{ ++ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ struct bfq_queue **async_bfqq = NULL; ++ struct bfq_queue *bfqq; ++ struct bfq_group *bfqg; ++ ++ rcu_read_lock(); ++ ++ bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio)); ++ if (!bfqg) { ++ bfqq = &bfqd->oom_bfqq; ++ goto out; ++ } ++ ++ if (!is_sync) { ++ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, ++ ioprio); ++ bfqq = *async_bfqq; ++ if (bfqq) ++ goto out; ++ } ++ ++ bfqq = kmem_cache_alloc_node(bfq_pool, ++ GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN, ++ bfqd->queue->node); ++ ++ if (bfqq) { ++ bfq_init_bfqq(bfqd, bfqq, bic, current->pid, ++ is_sync); ++ bfq_init_entity(&bfqq->entity, bfqg); ++ bfq_log_bfqq(bfqd, bfqq, "allocated"); ++ } else { ++ bfqq = &bfqd->oom_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); ++ goto out; ++ } ++ ++ /* ++ * Pin the queue now that it's allocated, scheduler exit will ++ * prune it. ++ */ ++ if (async_bfqq) { ++ bfqq->ref++; /* ++ * Extra group reference, w.r.t. sync ++ * queue. This extra reference is removed ++ * only if bfqq->bfqg disappears, to ++ * guarantee that this queue is not freed ++ * until its group goes away. ++ */ ++ bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d", ++ bfqq, bfqq->ref); ++ *async_bfqq = bfqq; ++ } ++ ++out: ++ bfqq->ref++; /* get a process reference to this queue */ ++ bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref); ++ rcu_read_unlock(); ++ return bfqq; ++} ++ ++static void bfq_update_io_thinktime(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic) ++{ ++ struct bfq_ttime *ttime = &bic->ttime; ++ u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request; ++ ++ elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle); ++ ++ ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8; ++ ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8); ++ ttime->ttime_mean = div64_ul(ttime->ttime_total + 128, ++ ttime->ttime_samples); ++} ++ ++static void ++bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ bfqq->seek_history <<= 1; ++ bfqq->seek_history |= BFQ_RQ_SEEKY(bfqd, bfqq->last_request_pos, rq); ++} ++ ++static void bfq_update_has_short_ttime(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ bool has_short_ttime = true; ++ ++ /* ++ * No need to update has_short_ttime if bfqq is async or in ++ * idle io prio class, or if bfq_slice_idle is zero, because ++ * no device idling is performed for bfqq in this case. ++ */ ++ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) || ++ bfqd->bfq_slice_idle == 0) ++ return; ++ ++ /* Idle window just restored, statistics are meaningless. */ ++ if (time_is_after_eq_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) ++ return; ++ ++ /* Think time is infinite if no process is linked to ++ * bfqq. Otherwise check average think time to ++ * decide whether to mark as has_short_ttime ++ */ ++ if (atomic_read(&bic->icq.ioc->active_ref) == 0 || ++ (bfq_sample_valid(bic->ttime.ttime_samples) && ++ bic->ttime.ttime_mean > bfqd->bfq_slice_idle)) ++ has_short_ttime = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d", ++ has_short_ttime); ++ ++ if (has_short_ttime) ++ bfq_mark_bfqq_has_short_ttime(bfqq); ++ else ++ bfq_clear_bfqq_has_short_ttime(bfqq); ++} ++ ++/* ++ * Called when a new fs request (rq) is added to bfqq. Check if there's ++ * something we should do about it. ++ */ ++static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ struct bfq_io_cq *bic = RQ_BIC(rq); ++ ++ if (rq->cmd_flags & REQ_META) ++ bfqq->meta_pending++; ++ ++ bfq_update_io_thinktime(bfqd, bic); ++ bfq_update_has_short_ttime(bfqd, bfqq, bic); ++ bfq_update_io_seektime(bfqd, bfqq, rq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "has_short_ttime=%d (seeky %d)", ++ bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq)); ++ ++ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ ++ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { ++ bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 && ++ blk_rq_sectors(rq) < 32; ++ bool budget_timeout = bfq_bfqq_budget_timeout(bfqq); ++ ++ /* ++ * There is just this request queued: if ++ * - the request is small, and ++ * - we are idling to boost throughput, and ++ * - the queue is not to be expired, ++ * then just exit. ++ * ++ * In this way, if the device is being idled to wait ++ * for a new request from the in-service queue, we ++ * avoid unplugging the device and committing the ++ * device to serve just a small request. In contrast ++ * we wait for the block layer to decide when to ++ * unplug the device: hopefully, new requests will be ++ * merged to this one quickly, then the device will be ++ * unplugged and larger requests will be dispatched. ++ */ ++ if (small_req && idling_boosts_thr_without_issues(bfqd, bfqq) && ++ !budget_timeout) ++ return; ++ ++ /* ++ * A large enough request arrived, or idling is being ++ * performed to preserve service guarantees, or ++ * finally the queue is to be expired: in all these ++ * cases disk idling is to be stopped, so clear ++ * wait_request flag and reset timer. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ hrtimer_try_to_cancel(&bfqd->idle_slice_timer); ++ bfqg_stats_update_idle_time(bfqq_group(bfqq)); ++ ++ /* ++ * The queue is not empty, because a new request just ++ * arrived. Hence we can safely expire the queue, in ++ * case of budget timeout, without risking that the ++ * timestamps of the queue are not updated correctly. ++ * See [1] for more details. ++ */ ++ if (budget_timeout) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ ++ /* ++ * Let the request rip immediately, or let a new queue be ++ * selected if bfqq has just been expired. ++ */ ++ __blk_run_queue(bfqd->queue); ++ } ++} ++ ++static void bfq_insert_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq; ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ ++ /* ++ * An unplug may trigger a requeue of a request from the device ++ * driver: make sure we are in process context while trying to ++ * merge two bfq_queues. ++ */ ++ if (!in_interrupt()) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true); ++ if (new_bfqq) { ++ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq) ++ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1); ++ /* ++ * Release the request's reference to the old bfqq ++ * and make sure one is taken to the shared queue. ++ */ ++ new_bfqq->allocated[rq_data_dir(rq)]++; ++ bfqq->allocated[rq_data_dir(rq)]--; ++ new_bfqq->ref++; ++ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq) ++ bfq_merge_bfqqs(bfqd, RQ_BIC(rq), ++ bfqq, new_bfqq); ++ ++ bfq_clear_bfqq_just_created(bfqq); ++ /* ++ * rq is about to be enqueued into new_bfqq, ++ * release rq reference on bfqq ++ */ ++ bfq_put_queue(bfqq); ++ rq->elv.priv[1] = new_bfqq; ++ bfqq = new_bfqq; ++ } ++ } ++ ++ bfq_add_request(rq); ++ ++ rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; ++ list_add_tail(&rq->queuelist, &bfqq->fifo); ++ ++ bfq_rq_enqueued(bfqd, bfqq, rq); ++} ++ ++static void bfq_update_hw_tag(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ ++ bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver, ++ bfqd->rq_in_driver); ++ ++ if (bfqd->hw_tag == 1) ++ return; ++ ++ /* ++ * This sample is valid if the number of outstanding requests ++ * is large enough to allow a queueing behavior. Note that the ++ * sum is not exact, as it's not taking into account deactivated ++ * requests. ++ */ ++ if (bfqd->rq_in_driver + bfqd->queued <= BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ /* ++ * If active queue hasn't enough requests and can idle, bfq might not ++ * dispatch sufficient requests to hardware. Don't zero hw_tag in this ++ * case ++ */ ++ if (bfqq && bfq_bfqq_has_short_ttime(bfqq) && ++ bfqq->dispatched + bfqq->queued[0] + bfqq->queued[1] < ++ BFQ_HW_QUEUE_THRESHOLD && bfqd->rq_in_driver < BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES) ++ return; ++ ++ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD; ++ bfqd->max_rq_in_driver = 0; ++ bfqd->hw_tag_samples = 0; ++} ++ ++static void bfq_completed_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ u64 now_ns; ++ u32 delta_us; ++ ++ bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left", ++ blk_rq_sectors(rq)); ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ bfq_update_hw_tag(bfqd); ++ ++ BUG_ON(!bfqd->rq_in_driver); ++ BUG_ON(!bfqq->dispatched); ++ bfqd->rq_in_driver--; ++ bfqq->dispatched--; ++ bfqg_stats_update_completion(bfqq_group(bfqq), ++ rq->start_time_ns, ++ rq->io_start_time_ns, ++ rq->cmd_flags); ++ ++ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ /* ++ * Set budget_timeout (which we overload to store the ++ * time at which the queue remains with no backlog and ++ * no outstanding request; used by the weight-raising ++ * mechanism). ++ */ ++ bfqq->budget_timeout = jiffies; ++ ++ bfq_weights_tree_remove(bfqd, bfqq); ++ } ++ ++ now_ns = ktime_get_ns(); ++ ++ RQ_BIC(rq)->ttime.last_end_request = now_ns; ++ ++ /* ++ * Using us instead of ns, to get a reasonable precision in ++ * computing rate in next check. ++ */ ++ delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC); ++ ++ bfq_log(bfqd, "delta %uus/%luus max_size %u rate %llu/%llu", ++ delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size, ++ delta_us > 0 ? ++ (USEC_PER_SEC* ++ (u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us)) ++ >>BFQ_RATE_SHIFT : ++ (USEC_PER_SEC* ++ (u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT, ++ (USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT); ++ ++ /* ++ * If the request took rather long to complete, and, according ++ * to the maximum request size recorded, this completion latency ++ * implies that the request was certainly served at a very low ++ * rate (less than 1M sectors/sec), then the whole observation ++ * interval that lasts up to this time instant cannot be a ++ * valid time interval for computing a new peak rate. Invoke ++ * bfq_update_rate_reset to have the following three steps ++ * taken: ++ * - close the observation interval at the last (previous) ++ * request dispatch or completion ++ * - compute rate, if possible, for that observation interval ++ * - reset to zero samples, which will trigger a proper ++ * re-initialization of the observation interval on next ++ * dispatch ++ */ ++ if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC && ++ (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us < ++ 1UL<<(BFQ_RATE_SHIFT - 10)) ++ bfq_update_rate_reset(bfqd, NULL); ++ bfqd->last_completion = now_ns; ++ ++ /* ++ * If we are waiting to discover whether the request pattern ++ * of the task associated with the queue is actually ++ * isochronous, and both requisites for this condition to hold ++ * are now satisfied, then compute soft_rt_next_start (see the ++ * comments on the function bfq_bfqq_softrt_next_start()). We ++ * do not compute soft_rt_next_start if bfqq is in interactive ++ * weight raising (see the comments in bfq_bfqq_expire() for ++ * an explanation). We schedule this delayed update when bfqq ++ * expires, if it still has in-flight requests. ++ */ ++ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list) && ++ bfqq->wr_coeff != bfqd->bfq_wr_coeff) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ ++ /* ++ * If this is the in-service queue, check if it needs to be expired, ++ * or if we want to idle in case it has no pending requests. ++ */ ++ if (bfqd->in_service_queue == bfqq) { ++ if (bfq_bfqq_must_idle(bfqq)) { ++ if (bfqq->dispatched == 0) ++ bfq_arm_slice_timer(bfqd); ++ /* ++ * If we get here, we do not expire bfqq, even ++ * if bfqq was in budget timeout or had no ++ * more requests (as controlled in the next ++ * conditional instructions). The reason for ++ * not expiring bfqq is as follows. ++ * ++ * Here bfqq->dispatched > 0 holds, but ++ * bfq_bfqq_must_idle() returned true. This ++ * implies that, even if no request arrives ++ * for bfqq before bfqq->dispatched reaches 0, ++ * bfqq will, however, not be expired on the ++ * completion event that causes bfqq->dispatch ++ * to reach zero. In contrast, on this event, ++ * bfqq will start enjoying device idling ++ * (I/O-dispatch plugging). ++ * ++ * But, if we expired bfqq here, bfqq would ++ * not have the chance to enjoy device idling ++ * when bfqq->dispatched finally reaches ++ * zero. This would expose bfqq to violation ++ * of its reserved service guarantees. ++ */ ++ goto out; ++ } else if (bfq_may_expire_for_budg_timeout(bfqq)) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ else if (RB_EMPTY_ROOT(&bfqq->sort_list) && ++ (bfqq->dispatched == 0 || ++ !bfq_better_to_idle(bfqq))) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_NO_MORE_REQUESTS); ++ } ++ ++ if (!bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ ++out: ++ return; ++} ++ ++static int __bfq_may_queue(struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) { ++ bfq_clear_bfqq_must_alloc(bfqq); ++ return ELV_MQUEUE_MUST; ++ } ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++static int bfq_may_queue(struct request_queue *q, unsigned int op) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ /* ++ * Don't force setup of a queue from here, as a call to may_queue ++ * does not necessarily imply that a request actually will be ++ * queued. So just lookup a possibly existing queue, or return ++ * 'may queue' if that fails. ++ */ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (!bic) ++ return ELV_MQUEUE_MAY; ++ ++ bfqq = bic_to_bfqq(bic, op_is_sync(op)); ++ if (bfqq) ++ return __bfq_may_queue(bfqq); ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++/* ++ * Queue lock held here. ++ */ ++static void bfq_put_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ if (bfqq) { ++ const int rw = rq_data_dir(rq); ++ ++ BUG_ON(!bfqq->allocated[rw]); ++ bfqq->allocated[rw]--; ++ ++ rq->elv.priv[0] = NULL; ++ rq->elv.priv[1] = NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "%p, %d", ++ bfqq, bfqq->ref); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++/* ++ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this ++ * was the last process referring to that bfqq. ++ */ ++static struct bfq_queue * ++bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue"); ++ ++ put_io_context(bic->icq.ioc); ++ ++ if (bfqq_process_refs(bfqq) == 1) { ++ bfqq->pid = current->pid; ++ bfq_clear_bfqq_coop(bfqq); ++ bfq_clear_bfqq_split_coop(bfqq); ++ return bfqq; ++ } ++ ++ bic_set_bfqq(bic, NULL, 1); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); ++ return NULL; ++} ++ ++/* ++ * Allocate bfq data structures associated with this request. ++ */ ++static int bfq_set_request(struct request_queue *q, struct request *rq, ++ struct bio *bio, gfp_t gfp_mask) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq); ++ const int rw = rq_data_dir(rq); ++ const int is_sync = rq_is_sync(rq); ++ struct bfq_queue *bfqq; ++ unsigned long flags; ++ bool bfqq_already_existing = false, split = false; ++ ++ spin_lock_irqsave(q->queue_lock, flags); ++ ++ if (!bic) ++ goto queue_fail; ++ ++ bfq_check_ioprio_change(bic, bio); ++ ++ bfq_bic_update_cgroup(bic, bio); ++ ++new_queue: ++ bfqq = bic_to_bfqq(bic, is_sync); ++ if (!bfqq || bfqq == &bfqd->oom_bfqq) { ++ if (bfqq) ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); ++ ++ bic_set_bfqq(bic, bfqq, is_sync); ++ if (split && is_sync) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "was_in_list %d " ++ "was_in_large_burst %d " ++ "large burst in progress %d", ++ bic->was_in_burst_list, ++ bic->saved_in_large_burst, ++ bfqd->large_burst); ++ ++ if ((bic->was_in_burst_list && bfqd->large_burst) || ++ bic->saved_in_large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "marking in " ++ "large burst"); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ } else { ++ bfq_log_bfqq(bfqd, bfqq, ++ "clearing in " ++ "large burst"); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ if (bic->was_in_burst_list) ++ /* ++ * If bfqq was in the current ++ * burst list before being ++ * merged, then we have to add ++ * it back. And we do not need ++ * to increase burst_size, as ++ * we did not decrement ++ * burst_size when we removed ++ * bfqq from the burst list as ++ * a consequence of a merge ++ * (see comments in ++ * bfq_put_queue). In this ++ * respect, it would be rather ++ * costly to know whether the ++ * current burst list is still ++ * the same burst list from ++ * which bfqq was removed on ++ * the merge. To avoid this ++ * cost, if bfqq was in a ++ * burst list, then we add ++ * bfqq to the current burst ++ * list without any further ++ * check. This can cause ++ * inappropriate insertions, ++ * but rarely enough to not ++ * harm the detection of large ++ * bursts significantly. ++ */ ++ hlist_add_head(&bfqq->burst_list_node, ++ &bfqd->burst_list); ++ } ++ bfqq->split_time = jiffies; ++ } ++ } else { ++ /* If the queue was seeky for too long, break it apart. */ ++ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); ++ ++ /* Update bic before losing reference to bfqq */ ++ if (bfq_bfqq_in_large_burst(bfqq)) ++ bic->saved_in_large_burst = true; ++ ++ bfqq = bfq_split_bfqq(bic, bfqq); ++ split = true; ++ if (!bfqq) ++ goto new_queue; ++ else ++ bfqq_already_existing = true; ++ } ++ } ++ ++ bfqq->allocated[rw]++; ++ bfqq->ref++; ++ bfq_log_bfqq(bfqd, bfqq, "bfqq %p, %d", bfqq, bfqq->ref); ++ ++ rq->elv.priv[0] = bic; ++ rq->elv.priv[1] = bfqq; ++ ++ /* ++ * If a bfq_queue has only one process reference, it is owned ++ * by only one bfq_io_cq: we can set the bic field of the ++ * bfq_queue to the address of that structure. Also, if the ++ * queue has just been split, mark a flag so that the ++ * information is available to the other scheduler hooks. ++ */ ++ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { ++ bfqq->bic = bic; ++ if (split) { ++ /* ++ * If the queue has just been split from a shared ++ * queue, restore the idle window and the possible ++ * weight raising period. ++ */ ++ bfq_bfqq_resume_state(bfqq, bfqd, bic, ++ bfqq_already_existing); ++ } ++ } ++ ++ if (unlikely(bfq_bfqq_just_created(bfqq))) ++ bfq_handle_burst(bfqd, bfqq); ++ ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 0; ++ ++queue_fail: ++ bfq_schedule_dispatch(bfqd); ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 1; ++} ++ ++static void bfq_kick_queue(struct work_struct *work) ++{ ++ struct bfq_data *bfqd = ++ container_of(work, struct bfq_data, unplug_work); ++ struct request_queue *q = bfqd->queue; ++ ++ spin_lock_irq(q->queue_lock); ++ __blk_run_queue(q); ++ spin_unlock_irq(q->queue_lock); ++} ++ ++/* ++ * Handler of the expiration of the timer running if the in-service queue ++ * is idling inside its time slice. ++ */ ++static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer) ++{ ++ struct bfq_data *bfqd = container_of(timer, struct bfq_data, ++ idle_slice_timer); ++ struct bfq_queue *bfqq; ++ unsigned long flags; ++ enum bfqq_expiration reason; ++ ++ spin_lock_irqsave(bfqd->queue->queue_lock, flags); ++ ++ bfqq = bfqd->in_service_queue; ++ /* ++ * Theoretical race here: the in-service queue can be NULL or ++ * different from the queue that was idling if the timer handler ++ * spins on the queue_lock and a new request arrives for the ++ * current queue and there is a full dispatch cycle that changes ++ * the in-service queue. This can hardly happen, but in the worst ++ * case we just expire a queue too early. ++ */ ++ if (bfqq) { ++ bfq_log_bfqq(bfqd, bfqq, "expired"); ++ bfq_clear_bfqq_wait_request(bfqq); ++ ++ if (bfq_bfqq_budget_timeout(bfqq)) ++ /* ++ * Also here the queue can be safely expired ++ * for budget timeout without wasting ++ * guarantees ++ */ ++ reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0) ++ /* ++ * The queue may not be empty upon timer expiration, ++ * because we may not disable the timer when the ++ * first request of the in-service queue arrives ++ * during disk idling. ++ */ ++ reason = BFQ_BFQQ_TOO_IDLE; ++ else ++ goto schedule_dispatch; ++ ++ bfq_bfqq_expire(bfqd, bfqq, true, reason); ++ } ++ ++schedule_dispatch: ++ bfq_schedule_dispatch(bfqd); ++ ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags); ++ return HRTIMER_NORESTART; ++} ++ ++static void bfq_shutdown_timer_wq(struct bfq_data *bfqd) ++{ ++ hrtimer_cancel(&bfqd->idle_slice_timer); ++ cancel_work_sync(&bfqd->unplug_work); ++} ++ ++static void __bfq_put_async_bfqq(struct bfq_data *bfqd, ++ struct bfq_queue **bfqq_ptr) ++{ ++ struct bfq_group *root_group = bfqd->root_group; ++ struct bfq_queue *bfqq = *bfqq_ptr; ++ ++ bfq_log(bfqd, "%p", bfqq); ++ if (bfqq) { ++ bfq_bfqq_move(bfqd, bfqq, root_group); ++ bfq_log_bfqq(bfqd, bfqq, "putting %p, %d", ++ bfqq, bfqq->ref); ++ bfq_put_queue(bfqq); ++ *bfqq_ptr = NULL; ++ } ++} ++ ++/* ++ * Release all the bfqg references to its async queues. If we are ++ * deallocating the group these queues may still contain requests, so ++ * we reparent them to the root cgroup (i.e., the only one that will ++ * exist for sure until all the requests on a device are gone). ++ */ ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]); ++ ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); ++} ++ ++static void bfq_exit_queue(struct elevator_queue *e) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ struct request_queue *q = bfqd->queue; ++ struct bfq_queue *bfqq, *n; ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ spin_lock_irq(q->queue_lock); ++ ++ BUG_ON(bfqd->in_service_queue); ++ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) ++ bfq_deactivate_bfqq(bfqd, bfqq, false, false); ++ ++ spin_unlock_irq(q->queue_lock); ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ BUG_ON(hrtimer_active(&bfqd->idle_slice_timer)); ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ /* release oom-queue reference to root group */ ++ bfqg_put(bfqd->root_group); ++ ++ blkcg_deactivate_policy(q, &blkcg_policy_bfq); ++#else ++ bfq_put_async_queues(bfqd, bfqd->root_group); ++ kfree(bfqd->root_group); ++#endif ++ ++ kfree(bfqd); ++} ++ ++static void bfq_init_root_group(struct bfq_group *root_group, ++ struct bfq_data *bfqd) ++{ ++ int i; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ root_group->entity.parent = NULL; ++ root_group->my_entity = NULL; ++ root_group->bfqd = bfqd; ++#endif ++ root_group->rq_pos_tree = RB_ROOT; ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ root_group->sched_data.bfq_class_idle_last_service = jiffies; ++} ++ ++static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) ++{ ++ struct bfq_data *bfqd; ++ struct elevator_queue *eq; ++ ++ eq = elevator_alloc(q, e); ++ if (!eq) ++ return -ENOMEM; ++ ++ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); ++ if (!bfqd) { ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++ } ++ eq->elevator_data = bfqd; ++ ++ /* ++ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues. ++ * Grab a permanent reference to it, so that the normal code flow ++ * will not attempt to free it. ++ */ ++ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); ++ bfqd->oom_bfqq.ref++; ++ bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; ++ bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; ++ bfqd->oom_bfqq.entity.new_weight = ++ bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); ++ ++ /* oom_bfqq does not participate to bursts */ ++ bfq_clear_bfqq_just_created(&bfqd->oom_bfqq); ++ /* ++ * Trigger weight initialization, according to ioprio, at the ++ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio ++ * class won't be changed any more. ++ */ ++ bfqd->oom_bfqq.entity.prio_changed = 1; ++ ++ bfqd->queue = q; ++ ++ spin_lock_irq(q->queue_lock); ++ q->elevator = eq; ++ spin_unlock_irq(q->queue_lock); ++ ++ bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node); ++ if (!bfqd->root_group) ++ goto out_free; ++ bfq_init_root_group(bfqd->root_group, bfqd); ++ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); ++ ++ hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC, ++ HRTIMER_MODE_REL); ++ bfqd->idle_slice_timer.function = bfq_idle_slice_timer; ++ ++ bfqd->queue_weights_tree = RB_ROOT; ++ bfqd->num_groups_with_pending_reqs = 0; ++ ++ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue); ++ ++ INIT_LIST_HEAD(&bfqd->active_list); ++ INIT_LIST_HEAD(&bfqd->idle_list); ++ INIT_HLIST_HEAD(&bfqd->burst_list); ++ ++ bfqd->hw_tag = -1; ++ ++ bfqd->bfq_max_budget = bfq_default_max_budget; ++ ++ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0]; ++ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1]; ++ bfqd->bfq_back_max = bfq_back_max; ++ bfqd->bfq_back_penalty = bfq_back_penalty; ++ bfqd->bfq_slice_idle = bfq_slice_idle; ++ bfqd->bfq_timeout = bfq_timeout; ++ ++ bfqd->bfq_requests_within_timer = 120; ++ ++ bfqd->bfq_large_burst_thresh = 8; ++ bfqd->bfq_burst_interval = msecs_to_jiffies(180); ++ ++ bfqd->low_latency = true; ++ ++ /* ++ * Trade-off between responsiveness and fairness. ++ */ ++ bfqd->bfq_wr_coeff = 30; ++ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300); ++ bfqd->bfq_wr_max_time = 0; ++ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000); ++ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500); ++ bfqd->bfq_wr_max_softrt_rate = 7000; /* ++ * Approximate rate required ++ * to playback or record a ++ * high-definition compressed ++ * video. ++ */ ++ bfqd->wr_busy_queues = 0; ++ ++ /* ++ * Begin by assuming, optimistically, that the device peak ++ * rate is equal to 2/3 of the highest reference rate. ++ */ ++ bfqd->rate_dur_prod = ref_rate[blk_queue_nonrot(bfqd->queue)] * ++ ref_wr_duration[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->peak_rate = ref_rate[blk_queue_nonrot(bfqd->queue)] * 2 / 3; ++ ++ return 0; ++ ++out_free: ++ kfree(bfqd); ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++} ++ ++static void bfq_registered_queue(struct request_queue *q) ++{ ++ wbt_disable_default(q); ++} ++ ++static void bfq_slab_kill(void) ++{ ++ kmem_cache_destroy(bfq_pool); ++} ++ ++static int __init bfq_slab_setup(void) ++{ ++ bfq_pool = KMEM_CACHE(bfq_queue, 0); ++ if (!bfq_pool) ++ return -ENOMEM; ++ return 0; ++} ++ ++static ssize_t bfq_var_show(unsigned int var, char *page) ++{ ++ return sprintf(page, "%u\n", var); ++} ++ ++static ssize_t bfq_var_store(unsigned long *var, const char *page, ++ size_t count) ++{ ++ unsigned long new_val; ++ int ret = kstrtoul(page, 10, &new_val); ++ ++ if (ret == 0) ++ *var = new_val; ++ ++ return count; ++} ++ ++static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ ++ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ? ++ jiffies_to_msecs(bfqd->bfq_wr_max_time) : ++ jiffies_to_msecs(bfq_wr_duration(bfqd))); ++} ++ ++static ssize_t bfq_weights_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_queue *bfqq; ++ struct bfq_data *bfqd = e->elevator_data; ++ ssize_t num_char = 0; ++ ++ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n", ++ bfqd->queued); ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ num_char += sprintf(page + num_char, "Active:\n"); ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, nr_queued %d %d, ", ++ bfqq->pid, ++ bfqq->entity.weight, ++ bfqq->queued[0], ++ bfqq->queued[1]); ++ num_char += sprintf(page + num_char, ++ "dur %d/%u\n", ++ jiffies_to_msecs( ++ jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ num_char += sprintf(page + num_char, "Idle:\n"); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ jiffies_to_msecs(jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++ ++ return num_char; ++} ++ ++#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ u64 __data = __VAR; \ ++ if (__CONV == 1) \ ++ __data = jiffies_to_msecs(__data); \ ++ else if (__CONV == 2) \ ++ __data = div_u64(__data, NSEC_PER_MSEC); \ ++ return bfq_var_show(__data, (page)); \ ++} ++SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2); ++SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2); ++SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); ++SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); ++SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2); ++SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); ++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1); ++SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0); ++SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0); ++SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0); ++SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1); ++SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1); ++SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async, ++ 1); ++SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0); ++#undef SHOW_FUNCTION ++ ++#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ u64 __data = __VAR; \ ++ __data = div_u64(__data, NSEC_PER_USEC); \ ++ return bfq_var_show(__data, (page)); \ ++} ++USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle); ++#undef USEC_SHOW_FUNCTION ++ ++#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ ++static ssize_t \ ++__FUNC(struct elevator_queue *e, const char *page, size_t count) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ if (__CONV == 1) \ ++ *(__PTR) = msecs_to_jiffies(__data); \ ++ else if (__CONV == 2) \ ++ *(__PTR) = (u64)__data * NSEC_PER_MSEC; \ ++ else \ ++ *(__PTR) = __data; \ ++ return ret; \ ++} ++STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1, ++ INT_MAX, 2); ++STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1, ++ INT_MAX, 2); ++STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); ++STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, ++ INT_MAX, 0); ++STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2); ++STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX, ++ 1); ++STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_min_inter_arr_async_store, ++ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0, ++ INT_MAX, 0); ++#undef STORE_FUNCTION ++ ++#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ ++static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ *(__PTR) = (u64)__data * NSEC_PER_USEC; \ ++ return ret; \ ++} ++USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0, ++ UINT_MAX); ++#undef USEC_STORE_FUNCTION ++ ++/* do nothing for the moment */ ++static ssize_t bfq_weights_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ return count; ++} ++ ++static ssize_t bfq_max_budget_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data == 0) ++ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); ++ else { ++ if (__data > INT_MAX) ++ __data = INT_MAX; ++ bfqd->bfq_max_budget = __data; ++ } ++ ++ bfqd->bfq_user_max_budget = __data; ++ ++ return ret; ++} ++ ++/* ++ * Leaving this name to preserve name compatibility with cfq ++ * parameters, but this timeout is used for both sync and async. ++ */ ++static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data < 1) ++ __data = 1; ++ else if (__data > INT_MAX) ++ __data = INT_MAX; ++ ++ bfqd->bfq_timeout = msecs_to_jiffies(__data); ++ if (bfqd->bfq_user_max_budget == 0) ++ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); ++ ++ return ret; ++} ++ ++static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (!bfqd->strict_guarantees && __data == 1 ++ && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC) ++ bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC; ++ ++ bfqd->strict_guarantees = __data; ++ ++ return ret; ++} ++ ++static ssize_t bfq_low_latency_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (__data == 0 && bfqd->low_latency != 0) ++ bfq_end_wr(bfqd); ++ bfqd->low_latency = __data; ++ ++ return ret; ++} ++ ++#define BFQ_ATTR(name) \ ++ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store) ++ ++static struct elv_fs_entry bfq_attrs[] = { ++ BFQ_ATTR(fifo_expire_sync), ++ BFQ_ATTR(fifo_expire_async), ++ BFQ_ATTR(back_seek_max), ++ BFQ_ATTR(back_seek_penalty), ++ BFQ_ATTR(slice_idle), ++ BFQ_ATTR(slice_idle_us), ++ BFQ_ATTR(max_budget), ++ BFQ_ATTR(timeout_sync), ++ BFQ_ATTR(strict_guarantees), ++ BFQ_ATTR(low_latency), ++ BFQ_ATTR(wr_coeff), ++ BFQ_ATTR(wr_max_time), ++ BFQ_ATTR(wr_rt_max_time), ++ BFQ_ATTR(wr_min_idle_time), ++ BFQ_ATTR(wr_min_inter_arr_async), ++ BFQ_ATTR(wr_max_softrt_rate), ++ BFQ_ATTR(weights), ++ __ATTR_NULL ++}; ++ ++static struct elevator_type iosched_bfq = { ++ .ops.sq = { ++ .elevator_merge_fn = bfq_merge, ++ .elevator_merged_fn = bfq_merged_request, ++ .elevator_merge_req_fn = bfq_merged_requests, ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ .elevator_bio_merged_fn = bfq_bio_merged, ++#endif ++ .elevator_allow_bio_merge_fn = bfq_allow_bio_merge, ++ .elevator_allow_rq_merge_fn = bfq_allow_rq_merge, ++ .elevator_dispatch_fn = bfq_dispatch_requests, ++ .elevator_add_req_fn = bfq_insert_request, ++ .elevator_activate_req_fn = bfq_activate_request, ++ .elevator_deactivate_req_fn = bfq_deactivate_request, ++ .elevator_completed_req_fn = bfq_completed_request, ++ .elevator_former_req_fn = elv_rb_former_request, ++ .elevator_latter_req_fn = elv_rb_latter_request, ++ .elevator_init_icq_fn = bfq_init_icq, ++ .elevator_exit_icq_fn = bfq_exit_icq, ++ .elevator_set_req_fn = bfq_set_request, ++ .elevator_put_req_fn = bfq_put_request, ++ .elevator_may_queue_fn = bfq_may_queue, ++ .elevator_init_fn = bfq_init_queue, ++ .elevator_exit_fn = bfq_exit_queue, ++ .elevator_registered_fn = bfq_registered_queue, ++ }, ++ .icq_size = sizeof(struct bfq_io_cq), ++ .icq_align = __alignof__(struct bfq_io_cq), ++ .elevator_attrs = bfq_attrs, ++ .elevator_name = "bfq-sq", ++ .elevator_owner = THIS_MODULE, ++}; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct blkcg_policy blkcg_policy_bfq = { ++ .dfl_cftypes = bfq_blkg_files, ++ .legacy_cftypes = bfq_blkcg_legacy_files, ++ ++ .cpd_alloc_fn = bfq_cpd_alloc, ++ .cpd_init_fn = bfq_cpd_init, ++ .cpd_bind_fn = bfq_cpd_init, ++ .cpd_free_fn = bfq_cpd_free, ++ ++ .pd_alloc_fn = bfq_pd_alloc, ++ .pd_init_fn = bfq_pd_init, ++ .pd_offline_fn = bfq_pd_offline, ++ .pd_free_fn = bfq_pd_free, ++ .pd_reset_stats_fn = bfq_pd_reset_stats, ++}; ++#endif ++ ++static int __init bfq_init(void) ++{ ++ int ret; ++ char msg[60] = "BFQ I/O-scheduler: v9"; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ ret = blkcg_policy_register(&blkcg_policy_bfq); ++ if (ret) ++ return ret; ++#endif ++ ++ ret = -ENOMEM; ++ if (bfq_slab_setup()) ++ goto err_pol_unreg; ++ ++ /* ++ * Times to load large popular applications for the typical ++ * systems installed on the reference devices (see the ++ * comments before the definition of the next ++ * array). Actually, we use slightly lower values, as the ++ * estimated peak rate tends to be smaller than the actual ++ * peak rate. The reason for this last fact is that estimates ++ * are computed over much shorter time intervals than the long ++ * intervals typically used for benchmarking. Why? First, to ++ * adapt more quickly to variations. Second, because an I/O ++ * scheduler cannot rely on a peak-rate-evaluation workload to ++ * be run for a long time. ++ */ ++ ref_wr_duration[0] = msecs_to_jiffies(7000); /* actually 8 sec */ ++ ref_wr_duration[1] = msecs_to_jiffies(2500); /* actually 3 sec */ ++ ++ ret = elv_register(&iosched_bfq); ++ if (ret) ++ goto slab_kill; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ strcat(msg, " (with cgroups support)"); ++#endif ++ pr_info("%s", msg); ++ ++ return 0; ++ ++slab_kill: ++ bfq_slab_kill(); ++err_pol_unreg: ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ return ret; ++} ++ ++static void __exit bfq_exit(void) ++{ ++ elv_unregister(&iosched_bfq); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ bfq_slab_kill(); ++} ++ ++module_init(bfq_init); ++module_exit(bfq_exit); ++ ++MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente"); ++MODULE_LICENSE("GPL"); +diff --git a/block/bfq.h b/block/bfq.h +new file mode 100644 +index 000000000000..0177fc7205d7 +--- /dev/null ++++ b/block/bfq.h +@@ -0,0 +1,1074 @@ ++/* ++ * BFQ v9: data structures and common functions prototypes. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> ++ * ++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> ++ * Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> ++ * ++ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org> ++ */ ++ ++#ifndef _BFQ_H ++#define _BFQ_H ++ ++#include <linux/hrtimer.h> ++#include <linux/blk-cgroup.h> ++ ++/* ++ * Define an alternative macro to compile cgroups support. This is one ++ * of the steps needed to let bfq-mq share the files bfq-sched.c and ++ * bfq-cgroup.c with bfq-sq. For bfq-mq, the macro ++ * BFQ_GROUP_IOSCHED_ENABLED will be defined as a function of whether ++ * the configuration option CONFIG_BFQ_MQ_GROUP_IOSCHED, and not ++ * CONFIG_BFQ_GROUP_IOSCHED, is defined. ++ */ ++#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED ++#define BFQ_GROUP_IOSCHED_ENABLED ++#endif ++ ++#define BFQ_IOPRIO_CLASSES 3 ++#define BFQ_CL_IDLE_TIMEOUT (HZ/5) ++ ++#define BFQ_MIN_WEIGHT 1 ++#define BFQ_MAX_WEIGHT 1000 ++#define BFQ_WEIGHT_CONVERSION_COEFF 10 ++ ++#define BFQ_DEFAULT_QUEUE_IOPRIO 4 ++ ++#define BFQ_WEIGHT_LEGACY_DFL 100 ++#define BFQ_DEFAULT_GRP_IOPRIO 0 ++#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE ++ ++/* ++ * Soft real-time applications are extremely more latency sensitive ++ * than interactive ones. Over-raise the weight of the former to ++ * privilege them against the latter. ++ */ ++#define BFQ_SOFTRT_WEIGHT_FACTOR 100 ++ ++struct bfq_entity; ++ ++/** ++ * struct bfq_service_tree - per ioprio_class service tree. ++ * ++ * Each service tree represents a B-WF2Q+ scheduler on its own. Each ++ * ioprio_class has its own independent scheduler, and so its own ++ * bfq_service_tree. All the fields are protected by the queue lock ++ * of the containing bfqd. ++ */ ++struct bfq_service_tree { ++ /* tree for active entities (i.e., those backlogged) */ ++ struct rb_root active; ++ /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ ++ struct rb_root idle; ++ ++ struct bfq_entity *first_idle; /* idle entity with minimum F_i */ ++ struct bfq_entity *last_idle; /* idle entity with maximum F_i */ ++ ++ u64 vtime; /* scheduler virtual time */ ++ /* scheduler weight sum; active and idle entities contribute to it */ ++ unsigned long wsum; ++}; ++ ++/** ++ * struct bfq_sched_data - multi-class scheduler. ++ * ++ * bfq_sched_data is the basic scheduler queue. It supports three ++ * ioprio_classes, and can be used either as a toplevel queue or as an ++ * intermediate queue in a hierarchical setup. ++ * ++ * The supported ioprio_classes are the same as in CFQ, in descending ++ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. ++ * Requests from higher priority queues are served before all the ++ * requests from lower priority queues; among requests of the same ++ * queue requests are served according to B-WF2Q+. ++ * ++ * The schedule is implemented by the service trees, plus the field ++ * @next_in_service, which points to the entity on the active trees ++ * that will be served next, if 1) no changes in the schedule occurs ++ * before the current in-service entity is expired, 2) the in-service ++ * queue becomes idle when it expires, and 3) if the entity pointed by ++ * in_service_entity is not a queue, then the in-service child entity ++ * of the entity pointed by in_service_entity becomes idle on ++ * expiration. This peculiar definition allows for the following ++ * optimization, not yet exploited: while a given entity is still in ++ * service, we already know which is the best candidate for next ++ * service among the other active entitities in the same parent ++ * entity. We can then quickly compare the timestamps of the ++ * in-service entity with those of such best candidate. ++ * ++ * All the fields are protected by the queue lock of the containing ++ * bfqd. ++ */ ++struct bfq_sched_data { ++ struct bfq_entity *in_service_entity; /* entity in service */ ++ /* head-of-the-line entity in the scheduler (see comments above) */ ++ struct bfq_entity *next_in_service; ++ /* array of service trees, one per ioprio_class */ ++ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; ++ /* last time CLASS_IDLE was served */ ++ unsigned long bfq_class_idle_last_service; ++ ++}; ++ ++/** ++ * struct bfq_weight_counter - counter of the number of all active queues ++ * with a given weight. ++ */ ++struct bfq_weight_counter { ++ unsigned int weight; /* weight of the queues this counter refers to */ ++ unsigned int num_active; /* nr of active queues with this weight */ ++ /* ++ * Weights tree member (see bfq_data's @queue_weights_tree) ++ */ ++ struct rb_node weights_node; ++}; ++ ++/** ++ * struct bfq_entity - schedulable entity. ++ * ++ * A bfq_entity is used to represent either a bfq_queue (leaf node in the ++ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each ++ * entity belongs to the sched_data of the parent group in the cgroup ++ * hierarchy. Non-leaf entities have also their own sched_data, stored ++ * in @my_sched_data. ++ * ++ * Each entity stores independently its priority values; this would ++ * allow different weights on different devices, but this ++ * functionality is not exported to userspace by now. Priorities and ++ * weights are updated lazily, first storing the new values into the ++ * new_* fields, then setting the @prio_changed flag. As soon as ++ * there is a transition in the entity state that allows the priority ++ * update to take place the effective and the requested priority ++ * values are synchronized. ++ * ++ * Unless cgroups are used, the weight value is calculated from the ++ * ioprio to export the same interface as CFQ. When dealing with ++ * ``well-behaved'' queues (i.e., queues that do not spend too much ++ * time to consume their budget and have true sequential behavior, and ++ * when there are no external factors breaking anticipation) the ++ * relative weights at each level of the cgroups hierarchy should be ++ * guaranteed. All the fields are protected by the queue lock of the ++ * containing bfqd. ++ */ ++struct bfq_entity { ++ struct rb_node rb_node; /* service_tree member */ ++ ++ /* ++ * Flag, true if the entity is on a tree (either the active or ++ * the idle one of its service_tree) or is in service. ++ */ ++ bool on_st; ++ ++ u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */ ++ u64 start; /* B-WF2Q+ start timestamp (aka S_i) */ ++ ++ /* tree the entity is enqueued into; %NULL if not on a tree */ ++ struct rb_root *tree; ++ ++ /* ++ * minimum start time of the (active) subtree rooted at this ++ * entity; used for O(log N) lookups into active trees ++ */ ++ u64 min_start; ++ ++ /* amount of service received during the last service slot */ ++ int service; ++ ++ /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ ++ int budget; ++ ++ unsigned int weight; /* weight of the queue */ ++ unsigned int new_weight; /* next weight if a change is in progress */ ++ ++ /* original weight, used to implement weight boosting */ ++ unsigned int orig_weight; ++ ++ /* parent entity, for hierarchical scheduling */ ++ struct bfq_entity *parent; ++ ++ /* ++ * For non-leaf nodes in the hierarchy, the associated ++ * scheduler queue, %NULL on leaf nodes. ++ */ ++ struct bfq_sched_data *my_sched_data; ++ /* the scheduler queue this entity belongs to */ ++ struct bfq_sched_data *sched_data; ++ ++ /* flag, set to request a weight, ioprio or ioprio_class change */ ++ int prio_changed; ++ ++ /* flag, set if the entity is counted in groups_with_pending_reqs */ ++ bool in_groups_with_pending_reqs; ++}; ++ ++struct bfq_group; ++ ++/** ++ * struct bfq_queue - leaf schedulable entity. ++ * ++ * A bfq_queue is a leaf request queue; it can be associated with an ++ * io_context or more, if it is async or shared between cooperating ++ * processes. @cgroup holds a reference to the cgroup, to be sure that it ++ * does not disappear while a bfqq still references it (mostly to avoid ++ * races between request issuing and task migration followed by cgroup ++ * destruction). ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_queue { ++ /* reference counter */ ++ int ref; ++ /* parent bfq_data */ ++ struct bfq_data *bfqd; ++ ++ /* current ioprio and ioprio class */ ++ unsigned short ioprio, ioprio_class; ++ /* next ioprio and ioprio class if a change is in progress */ ++ unsigned short new_ioprio, new_ioprio_class; ++ ++ /* ++ * Shared bfq_queue if queue is cooperating with one or more ++ * other queues. ++ */ ++ struct bfq_queue *new_bfqq; ++ /* request-position tree member (see bfq_group's @rq_pos_tree) */ ++ struct rb_node pos_node; ++ /* request-position tree root (see bfq_group's @rq_pos_tree) */ ++ struct rb_root *pos_root; ++ ++ /* sorted list of pending requests */ ++ struct rb_root sort_list; ++ /* if fifo isn't expired, next request to serve */ ++ struct request *next_rq; ++ /* number of sync and async requests queued */ ++ int queued[2]; ++ /* number of sync and async requests currently allocated */ ++ int allocated[2]; ++ /* number of pending metadata requests */ ++ int meta_pending; ++ /* fifo list of requests in sort_list */ ++ struct list_head fifo; ++ ++ /* entity representing this queue in the scheduler */ ++ struct bfq_entity entity; ++ ++ /* pointer to the weight counter associated with this queue */ ++ struct bfq_weight_counter *weight_counter; ++ ++ /* maximum budget allowed from the feedback mechanism */ ++ int max_budget; ++ /* budget expiration (in jiffies) */ ++ unsigned long budget_timeout; ++ ++ /* number of requests on the dispatch list or inside driver */ ++ int dispatched; ++ ++ unsigned int flags; /* status flags.*/ ++ ++ /* node for active/idle bfqq list inside parent bfqd */ ++ struct list_head bfqq_list; ++ ++ /* bit vector: a 1 for each seeky requests in history */ ++ u32 seek_history; ++ ++ /* node for the device's burst list */ ++ struct hlist_node burst_list_node; ++ ++ /* position of the last request enqueued */ ++ sector_t last_request_pos; ++ ++ /* Number of consecutive pairs of request completion and ++ * arrival, such that the queue becomes idle after the ++ * completion, but the next request arrives within an idle ++ * time slice; used only if the queue's IO_bound flag has been ++ * cleared. ++ */ ++ unsigned int requests_within_timer; ++ ++ /* pid of the process owning the queue, used for logging purposes */ ++ pid_t pid; ++ ++ /* ++ * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL ++ * if the queue is shared. ++ */ ++ struct bfq_io_cq *bic; ++ ++ /* current maximum weight-raising time for this queue */ ++ unsigned long wr_cur_max_time; ++ /* ++ * Minimum time instant such that, only if a new request is ++ * enqueued after this time instant in an idle @bfq_queue with ++ * no outstanding requests, then the task associated with the ++ * queue it is deemed as soft real-time (see the comments on ++ * the function bfq_bfqq_softrt_next_start()) ++ */ ++ unsigned long soft_rt_next_start; ++ /* ++ * Start time of the current weight-raising period if ++ * the @bfq-queue is being weight-raised, otherwise ++ * finish time of the last weight-raising period. ++ */ ++ unsigned long last_wr_start_finish; ++ /* factor by which the weight of this queue is multiplied */ ++ unsigned int wr_coeff; ++ /* ++ * Time of the last transition of the @bfq_queue from idle to ++ * backlogged. ++ */ ++ unsigned long last_idle_bklogged; ++ /* ++ * Cumulative service received from the @bfq_queue since the ++ * last transition from idle to backlogged. ++ */ ++ unsigned long service_from_backlogged; ++ /* ++ * Cumulative service received from the @bfq_queue since its ++ * last transition to weight-raised state. ++ */ ++ unsigned long service_from_wr; ++ /* ++ * Value of wr start time when switching to soft rt ++ */ ++ unsigned long wr_start_at_switch_to_srt; ++ ++ unsigned long split_time; /* time of last split */ ++ ++ unsigned long first_IO_time; /* time of first I/O for this queue */ ++ ++ /* max service rate measured so far */ ++ u32 max_service_rate; ++ /* ++ * Ratio between the service received by bfqq while it is in ++ * service, and the cumulative service (of requests of other ++ * queues) that may be injected while bfqq is empty but still ++ * in service. To increase precision, the coefficient is ++ * measured in tenths of unit. Here are some example of (1) ++ * ratios, (2) resulting percentages of service injected ++ * w.r.t. to the total service dispatched while bfqq is in ++ * service, and (3) corresponding values of the coefficient: ++ * 1 (50%) -> 10 ++ * 2 (33%) -> 20 ++ * 10 (9%) -> 100 ++ * 9.9 (9%) -> 99 ++ * 1.5 (40%) -> 15 ++ * 0.5 (66%) -> 5 ++ * 0.1 (90%) -> 1 ++ * ++ * So, if the coefficient is lower than 10, then ++ * injected service is more than bfqq service. ++ */ ++ unsigned int inject_coeff; ++ /* amount of service injected in current service slot */ ++ unsigned int injected_service; ++}; ++ ++/** ++ * struct bfq_ttime - per process thinktime stats. ++ */ ++struct bfq_ttime { ++ u64 last_end_request; /* completion time of last request */ ++ ++ u64 ttime_total; /* total process thinktime */ ++ unsigned long ttime_samples; /* number of thinktime samples */ ++ u64 ttime_mean; /* average process thinktime */ ++ ++}; ++ ++/** ++ * struct bfq_io_cq - per (request_queue, io_context) structure. ++ */ ++struct bfq_io_cq { ++ /* associated io_cq structure */ ++ struct io_cq icq; /* must be the first member */ ++ /* array of two process queues, the sync and the async */ ++ struct bfq_queue *bfqq[2]; ++ /* associated @bfq_ttime struct */ ++ struct bfq_ttime ttime; ++ /* per (request_queue, blkcg) ioprio */ ++ int ioprio; ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ uint64_t blkcg_serial_nr; /* the current blkcg serial */ ++#endif ++ ++ /* ++ * Snapshot of the has_short_time flag before merging; taken ++ * to remember its value while the queue is merged, so as to ++ * be able to restore it in case of split. ++ */ ++ bool saved_has_short_ttime; ++ /* ++ * Same purpose as the previous two fields for the I/O bound ++ * classification of a queue. ++ */ ++ bool saved_IO_bound; ++ ++ /* ++ * Same purpose as the previous fields for the value of the ++ * field keeping the queue's belonging to a large burst ++ */ ++ bool saved_in_large_burst; ++ /* ++ * True if the queue belonged to a burst list before its merge ++ * with another cooperating queue. ++ */ ++ bool was_in_burst_list; ++ ++ /* ++ * Similar to previous fields: save wr information. ++ */ ++ unsigned long saved_wr_coeff; ++ unsigned long saved_last_wr_start_finish; ++ unsigned long saved_wr_start_at_switch_to_srt; ++ unsigned int saved_wr_cur_max_time; ++}; ++ ++/** ++ * struct bfq_data - per-device data structure. ++ * ++ * All the fields are protected by the @queue lock. ++ */ ++struct bfq_data { ++ /* request queue for the device */ ++ struct request_queue *queue; ++ ++ /* root bfq_group for the device */ ++ struct bfq_group *root_group; ++ ++ /* ++ * rbtree of weight counters of @bfq_queues, sorted by ++ * weight. Used to keep track of whether all @bfq_queues have ++ * the same weight. The tree contains one counter for each ++ * distinct weight associated to some active and not ++ * weight-raised @bfq_queue (see the comments to the functions ++ * bfq_weights_tree_[add|remove] for further details). ++ */ ++ struct rb_root queue_weights_tree; ++ ++ /* ++ * Number of groups with at least one descendant process that ++ * has at least one request waiting for completion. Note that ++ * this accounts for also requests already dispatched, but not ++ * yet completed. Therefore this number of groups may differ ++ * (be larger) than the number of active groups, as a group is ++ * considered active only if its corresponding entity has ++ * descendant queues with at least one request queued. This ++ * number is used to decide whether a scenario is symmetric. ++ * For a detailed explanation see comments on the computation ++ * of the variable asymmetric_scenario in the function ++ * bfq_better_to_idle(). ++ * ++ * However, it is hard to compute this number exactly, for ++ * groups with multiple descendant processes. Consider a group ++ * that is inactive, i.e., that has no descendant process with ++ * pending I/O inside BFQ queues. Then suppose that ++ * num_groups_with_pending_reqs is still accounting for this ++ * group, because the group has descendant processes with some ++ * I/O request still in flight. num_groups_with_pending_reqs ++ * should be decremented when the in-flight request of the ++ * last descendant process is finally completed (assuming that ++ * nothing else has changed for the group in the meantime, in ++ * terms of composition of the group and active/inactive state of child ++ * groups and processes). To accomplish this, an additional ++ * pending-request counter must be added to entities, and must ++ * be updated correctly. To avoid this additional field and operations, ++ * we resort to the following tradeoff between simplicity and ++ * accuracy: for an inactive group that is still counted in ++ * num_groups_with_pending_reqs, we decrement ++ * num_groups_with_pending_reqs when the first descendant ++ * process of the group remains with no request waiting for ++ * completion. ++ * ++ * Even this simpler decrement strategy requires a little ++ * carefulness: to avoid multiple decrements, we flag a group, ++ * more precisely an entity representing a group, as still ++ * counted in num_groups_with_pending_reqs when it becomes ++ * inactive. Then, when the first descendant queue of the ++ * entity remains with no request waiting for completion, ++ * num_groups_with_pending_reqs is decremented, and this flag ++ * is reset. After this flag is reset for the entity, ++ * num_groups_with_pending_reqs won't be decremented any ++ * longer in case a new descendant queue of the entity remains ++ * with no request waiting for completion. ++ */ ++ unsigned int num_groups_with_pending_reqs; ++ ++ /* ++ * Per-class (RT, BE, IDLE) number of bfq_queues containing ++ * requests (including the queue in service, even if it is ++ * idling). ++ */ ++ unsigned int busy_queues[3]; ++ /* number of weight-raised busy @bfq_queues */ ++ int wr_busy_queues; ++ /* number of queued requests */ ++ int queued; ++ /* number of requests dispatched and waiting for completion */ ++ int rq_in_driver; ++ ++ /* ++ * Maximum number of requests in driver in the last ++ * @hw_tag_samples completed requests. ++ */ ++ int max_rq_in_driver; ++ /* number of samples used to calculate hw_tag */ ++ int hw_tag_samples; ++ /* flag set to one if the driver is showing a queueing behavior */ ++ int hw_tag; ++ ++ /* number of budgets assigned */ ++ int budgets_assigned; ++ ++ /* ++ * Timer set when idling (waiting) for the next request from ++ * the queue in service. ++ */ ++ struct hrtimer idle_slice_timer; ++ /* delayed work to restart dispatching on the request queue */ ++ struct work_struct unplug_work; ++ ++ /* bfq_queue in service */ ++ struct bfq_queue *in_service_queue; ++ /* bfq_io_cq (bic) associated with the @in_service_queue */ ++ struct bfq_io_cq *in_service_bic; ++ ++ /* on-disk position of the last served request */ ++ sector_t last_position; ++ ++ /* position of the last served request for the in-service queue */ ++ sector_t in_serv_last_pos; ++ ++ /* time of last request completion (ns) */ ++ u64 last_completion; ++ ++ /* time of first rq dispatch in current observation interval (ns) */ ++ u64 first_dispatch; ++ /* time of last rq dispatch in current observation interval (ns) */ ++ u64 last_dispatch; ++ ++ /* beginning of the last budget */ ++ ktime_t last_budget_start; ++ /* beginning of the last idle slice */ ++ ktime_t last_idling_start; ++ ++ /* number of samples in current observation interval */ ++ int peak_rate_samples; ++ /* num of samples of seq dispatches in current observation interval */ ++ u32 sequential_samples; ++ /* total num of sectors transferred in current observation interval */ ++ u64 tot_sectors_dispatched; ++ /* max rq size seen during current observation interval (sectors) */ ++ u32 last_rq_max_size; ++ /* time elapsed from first dispatch in current observ. interval (us) */ ++ u64 delta_from_first; ++ /* ++ * Current estimate of the device peak rate, measured in ++ * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by ++ * BFQ_RATE_SHIFT is performed to increase precision in ++ * fixed-point calculations. ++ */ ++ u32 peak_rate; ++ ++ /* maximum budget allotted to a bfq_queue before rescheduling */ ++ int bfq_max_budget; ++ ++ /* list of all the bfq_queues active on the device */ ++ struct list_head active_list; ++ /* list of all the bfq_queues idle on the device */ ++ struct list_head idle_list; ++ ++ /* ++ * Timeout for async/sync requests; when it fires, requests ++ * are served in fifo order. ++ */ ++ u64 bfq_fifo_expire[2]; ++ /* weight of backward seeks wrt forward ones */ ++ unsigned int bfq_back_penalty; ++ /* maximum allowed backward seek */ ++ unsigned int bfq_back_max; ++ /* maximum idling time */ ++ u32 bfq_slice_idle; ++ ++ /* user-configured max budget value (0 for auto-tuning) */ ++ int bfq_user_max_budget; ++ /* ++ * Timeout for bfq_queues to consume their budget; used to ++ * prevent seeky queues from imposing long latencies to ++ * sequential or quasi-sequential ones (this also implies that ++ * seeky queues cannot receive guarantees in the service ++ * domain; after a timeout they are charged for the time they ++ * have been in service, to preserve fairness among them, but ++ * without service-domain guarantees). ++ */ ++ unsigned int bfq_timeout; ++ ++ /* ++ * Number of consecutive requests that must be issued within ++ * the idle time slice to set again idling to a queue which ++ * was marked as non-I/O-bound (see the definition of the ++ * IO_bound flag for further details). ++ */ ++ unsigned int bfq_requests_within_timer; ++ ++ /* ++ * Force device idling whenever needed to provide accurate ++ * service guarantees, without caring about throughput ++ * issues. CAVEAT: this may even increase latencies, in case ++ * of useless idling for processes that did stop doing I/O. ++ */ ++ bool strict_guarantees; ++ ++ /* ++ * Last time at which a queue entered the current burst of ++ * queues being activated shortly after each other; for more ++ * details about this and the following parameters related to ++ * a burst of activations, see the comments on the function ++ * bfq_handle_burst. ++ */ ++ unsigned long last_ins_in_burst; ++ /* ++ * Reference time interval used to decide whether a queue has ++ * been activated shortly after @last_ins_in_burst. ++ */ ++ unsigned long bfq_burst_interval; ++ /* number of queues in the current burst of queue activations */ ++ int burst_size; ++ ++ /* common parent entity for the queues in the burst */ ++ struct bfq_entity *burst_parent_entity; ++ /* Maximum burst size above which the current queue-activation ++ * burst is deemed as 'large'. ++ */ ++ unsigned long bfq_large_burst_thresh; ++ /* true if a large queue-activation burst is in progress */ ++ bool large_burst; ++ /* ++ * Head of the burst list (as for the above fields, more ++ * details in the comments on the function bfq_handle_burst). ++ */ ++ struct hlist_head burst_list; ++ ++ /* if set to true, low-latency heuristics are enabled */ ++ bool low_latency; ++ /* ++ * Maximum factor by which the weight of a weight-raised queue ++ * is multiplied. ++ */ ++ unsigned int bfq_wr_coeff; ++ /* maximum duration of a weight-raising period (jiffies) */ ++ unsigned int bfq_wr_max_time; ++ ++ /* Maximum weight-raising duration for soft real-time processes */ ++ unsigned int bfq_wr_rt_max_time; ++ /* ++ * Minimum idle period after which weight-raising may be ++ * reactivated for a queue (in jiffies). ++ */ ++ unsigned int bfq_wr_min_idle_time; ++ /* ++ * Minimum period between request arrivals after which ++ * weight-raising may be reactivated for an already busy async ++ * queue (in jiffies). ++ */ ++ unsigned long bfq_wr_min_inter_arr_async; ++ ++ /* Max service-rate for a soft real-time queue, in sectors/sec */ ++ unsigned int bfq_wr_max_softrt_rate; ++ /* ++ * Cached value of the product ref_rate*ref_wr_duration, used ++ * for computing the maximum duration of weight raising ++ * automatically. ++ */ ++ u64 rate_dur_prod; ++ ++ /* fallback dummy bfqq for extreme OOM conditions */ ++ struct bfq_queue oom_bfqq; ++}; ++ ++enum bfqq_state_flags { ++ BFQ_BFQQ_FLAG_just_created = 0, /* queue just allocated */ ++ BFQ_BFQQ_FLAG_busy, /* has requests or is in service */ ++ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ ++ BFQ_BFQQ_FLAG_non_blocking_wait_rq, /* ++ * waiting for a request ++ * without idling the device ++ */ ++ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ ++ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ ++ BFQ_BFQQ_FLAG_has_short_ttime, /* queue has a short think time */ ++ BFQ_BFQQ_FLAG_sync, /* synchronous queue */ ++ BFQ_BFQQ_FLAG_IO_bound, /* ++ * bfqq has timed-out at least once ++ * having consumed at most 2/10 of ++ * its budget ++ */ ++ BFQ_BFQQ_FLAG_in_large_burst, /* ++ * bfqq activated in a large burst, ++ * see comments to bfq_handle_burst. ++ */ ++ BFQ_BFQQ_FLAG_softrt_update, /* ++ * may need softrt-next-start ++ * update ++ */ ++ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ ++ BFQ_BFQQ_FLAG_split_coop /* shared bfqq will be split */ ++}; ++ ++#define BFQ_BFQQ_FNS(name) \ ++static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ ++{ \ ++ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ ++} ++ ++BFQ_BFQQ_FNS(just_created); ++BFQ_BFQQ_FNS(busy); ++BFQ_BFQQ_FNS(wait_request); ++BFQ_BFQQ_FNS(non_blocking_wait_rq); ++BFQ_BFQQ_FNS(must_alloc); ++BFQ_BFQQ_FNS(fifo_expire); ++BFQ_BFQQ_FNS(has_short_ttime); ++BFQ_BFQQ_FNS(sync); ++BFQ_BFQQ_FNS(IO_bound); ++BFQ_BFQQ_FNS(in_large_burst); ++BFQ_BFQQ_FNS(coop); ++BFQ_BFQQ_FNS(split_coop); ++BFQ_BFQQ_FNS(softrt_update); ++#undef BFQ_BFQQ_FNS ++ ++/* Logging facilities. */ ++#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE ++ ++static const char *checked_dev_name(const struct device *dev) ++{ ++ static const char nodev[] = "nodev"; ++ ++ if (dev) ++ return dev_name(dev); ++ ++ return nodev; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ assert_spin_locked((bfqd)->queue->queue_lock); \ ++ blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ ++ pr_crit("%s bfq%d%c %s [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __pbuf, __func__, ##args); \ ++} while (0) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ ++ pr_crit("%s %s [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ __pbuf, __func__, ##args); \ ++} while (0) ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ pr_crit("%s bfq%d%c [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ (bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __func__, ##args) ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ pr_crit("%s bfq [%s] " fmt "\n", \ ++ checked_dev_name((bfqd)->queue->backing_dev_info->dev), \ ++ __func__, ##args) ++ ++#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */ ++ ++#if !defined(CONFIG_BLK_DEV_IO_TRACE) ++ ++/* Avoid possible "unused-variable" warning. See commit message. */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) ((void) (bfqq)) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) ((void) (bfqg)) ++ ++#define bfq_log(bfqd, fmt, args...) do {} while (0) ++ ++#else /* CONFIG_BLK_DEV_IO_TRACE */ ++ ++#include <linux/blktrace_api.h> ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ assert_spin_locked((bfqd)->queue->queue_lock); \ ++ blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \ ++ (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __pbuf, __func__, ##args); \ ++} while (0) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ ++ blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, __pbuf, \ ++ __func__, ##args); \ ++} while (0) ++ ++#else /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __func__, ##args) ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) ++ ++#endif /* BFQ_GROUP_IOSCHED_ENABLED */ ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args) ++ ++#endif /* CONFIG_BLK_DEV_IO_TRACE */ ++#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */ ++ ++/* Expiration reasons. */ ++enum bfqq_expiration { ++ BFQ_BFQQ_TOO_IDLE = 0, /* ++ * queue has been idling for ++ * too long ++ */ ++ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ ++ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ ++ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ ++ BFQ_BFQQ_PREEMPTED /* preemption in progress */ ++}; ++ ++ ++struct bfqg_stats { ++#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP) ++ /* number of ios merged */ ++ struct blkg_rwstat merged; ++ /* total time spent on device in ns, may not be accurate w/ queueing */ ++ struct blkg_rwstat service_time; ++ /* total time spent waiting in scheduler queue in ns */ ++ struct blkg_rwstat wait_time; ++ /* number of IOs queued up */ ++ struct blkg_rwstat queued; ++ /* total disk time and nr sectors dispatched by this group */ ++ struct blkg_stat time; ++ /* sum of number of ios queued across all samples */ ++ struct blkg_stat avg_queue_size_sum; ++ /* count of samples taken for average */ ++ struct blkg_stat avg_queue_size_samples; ++ /* how many times this group has been removed from service tree */ ++ struct blkg_stat dequeue; ++ /* total time spent waiting for it to be assigned a timeslice. */ ++ struct blkg_stat group_wait_time; ++ /* time spent idling for this blkcg_gq */ ++ struct blkg_stat idle_time; ++ /* total time with empty current active q with other requests queued */ ++ struct blkg_stat empty_time; ++ /* fields after this shouldn't be cleared on stat reset */ ++ uint64_t start_group_wait_time; ++ uint64_t start_idle_time; ++ uint64_t start_empty_time; ++ uint16_t flags; ++#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */ ++}; ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++/* ++ * struct bfq_group_data - per-blkcg storage for the blkio subsystem. ++ * ++ * @ps: @blkcg_policy_storage that this structure inherits ++ * @weight: weight of the bfq_group ++ */ ++struct bfq_group_data { ++ /* must be the first member */ ++ struct blkcg_policy_data pd; ++ ++ unsigned int weight; ++}; ++ ++/** ++ * struct bfq_group - per (device, cgroup) data structure. ++ * @entity: schedulable entity to insert into the parent group sched_data. ++ * @sched_data: own sched_data, to contain child entities (they may be ++ * both bfq_queues and bfq_groups). ++ * @bfqd: the bfq_data for the device this group acts upon. ++ * @async_bfqq: array of async queues for all the tasks belonging to ++ * the group, one queue per ioprio value per ioprio_class, ++ * except for the idle class that has only one queue. ++ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). ++ * @my_entity: pointer to @entity, %NULL for the toplevel group; used ++ * to avoid too many special cases during group creation/ ++ * migration. ++ * @active_entities: number of active entities belonging to the group; ++ * unused for the root group. Used to know whether there ++ * are groups with more than one active @bfq_entity ++ * (see the comments to the function ++ * bfq_bfqq_may_idle()). ++ * @rq_pos_tree: rbtree sorted by next_request position, used when ++ * determining if two or more queues have interleaving ++ * requests (see bfq_find_close_cooperator()). ++ * ++ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup ++ * there is a set of bfq_groups, each one collecting the lower-level ++ * entities belonging to the group that are acting on the same device. ++ * ++ * Locking works as follows: ++ * o @bfqd is protected by the queue lock, RCU is used to access it ++ * from the readers. ++ * o All the other fields are protected by the @bfqd queue lock. ++ */ ++struct bfq_group { ++ /* must be the first member */ ++ struct blkg_policy_data pd; ++ ++ struct bfq_entity entity; ++ struct bfq_sched_data sched_data; ++ ++ void *bfqd; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct bfq_entity *my_entity; ++ ++ int active_entities; ++ ++ struct rb_root rq_pos_tree; ++ ++ struct bfqg_stats stats; ++}; ++ ++#else ++struct bfq_group { ++ struct bfq_sched_data sched_data; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct rb_root rq_pos_tree; ++}; ++#endif ++ ++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); ++ ++static unsigned int bfq_class_idx(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ return bfqq ? bfqq->ioprio_class - 1 : ++ BFQ_DEFAULT_GRP_CLASS - 1; ++} ++ ++static unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd) ++{ ++ return bfqd->busy_queues[0] + bfqd->busy_queues[1] + ++ bfqd->busy_queues[2]; ++} ++ ++static struct bfq_service_tree * ++bfq_entity_service_tree(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sched_data = entity->sched_data; ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned int idx = bfq_class_idx(entity); ++ ++ BUG_ON(idx >= BFQ_IOPRIO_CLASSES); ++ BUG_ON(sched_data == NULL); ++ ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "%p %d", ++ sched_data->service_tree + idx, idx); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "%p %d", ++ sched_data->service_tree + idx, idx); ++ } ++#endif ++ return sched_data->service_tree + idx; ++} ++ ++static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) ++{ ++ return bic->bfqq[is_sync]; ++} ++ ++static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, ++ bool is_sync) ++{ ++ bic->bfqq[is_sync] = bfqq; ++} ++ ++static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) ++{ ++ return bic->icq.q->elevator->elevator_data; ++} ++ ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *group_entity = bfqq->entity.parent; ++ ++ if (!group_entity) ++ group_entity = &bfqq->bfqd->root_group->entity; ++ ++ return container_of(group_entity, struct bfq_group, entity); ++} ++ ++#else ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ return bfqq->bfqd->root_group; ++} ++ ++#endif ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); ++static void bfq_put_queue(struct bfq_queue *bfqq); ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic); ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg); ++#ifdef BFQ_GROUP_IOSCHED_ENABLED ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); ++#endif ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++ ++#endif /* _BFQ_H */ +diff --git a/block/blk-mq.c b/block/blk-mq.c +index e3c39ea8e17b..7a57368841f6 100644 +--- a/block/blk-mq.c ++++ b/block/blk-mq.c +@@ -2878,6 +2878,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) + } + if (ret) + break; ++ if (q->elevator && q->elevator->type->ops.mq.depth_updated) ++ q->elevator->type->ops.mq.depth_updated(hctx); + } + + if (!ret) +diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h +index 6980014357d4..8c4568ea6884 100644 +--- a/include/linux/blkdev.h ++++ b/include/linux/blkdev.h +@@ -54,7 +54,7 @@ struct blk_stat_callback; + * Maximum number of blkcg policies allowed to be registered concurrently. + * Defined here to simplify include dependency. + */ +-#define BLKCG_MAX_POLS 5 ++#define BLKCG_MAX_POLS 7 + + typedef void (rq_end_io_fn)(struct request *, blk_status_t); + +@@ -127,6 +127,10 @@ typedef __u32 __bitwise req_flags_t; + #define RQF_MQ_POLL_SLEPT ((__force req_flags_t)(1 << 20)) + /* ->timeout has been called, don't expire again */ + #define RQF_TIMED_OUT ((__force req_flags_t)(1 << 21)) ++/* DEBUG: rq in bfq-mq dispatch list */ ++#define RQF_DISP_LIST ((__force req_flags_t)(1 << 22)) ++/* DEBUG: rq had get_rq_private executed on it */ ++#define RQF_GOT ((__force req_flags_t)(1 << 23)) + + /* flags that prevent us from merging requests: */ + #define RQF_NOMERGE_FLAGS \ +diff --git a/include/linux/elevator.h b/include/linux/elevator.h +index a02deea30185..a2bf4a6b9316 100644 +--- a/include/linux/elevator.h ++++ b/include/linux/elevator.h +@@ -99,6 +99,7 @@ struct elevator_mq_ops { + void (*exit_sched)(struct elevator_queue *); + int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int); + void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int); ++ void (*depth_updated)(struct blk_mq_hw_ctx *); + + bool (*allow_merge)(struct request_queue *, struct request *, struct bio *); + bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *); |