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From 9e47a80f690080c12ce607158b96c305707543b8 Mon Sep 17 00:00:00 2001
From: Con Kolivas <kernel@kolivas.org>
Date: Wed, 7 Dec 2016 21:23:01 +1100
Subject: [PATCH 12/16] Reinstate default Hz of 100 in combination with MuQSS
and -ck patches.
---
kernel/Kconfig.hz | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/kernel/Kconfig.hz b/kernel/Kconfig.hz
index 2a202a846757..1806fcac8f14 100644
--- a/kernel/Kconfig.hz
+++ b/kernel/Kconfig.hz
@@ -4,7 +4,8 @@
choice
prompt "Timer frequency"
- default HZ_250
+ default HZ_100 if SCHED_MUQSS
+ default HZ_250_NODEF if !SCHED_MUQSS
help
Allows the configuration of the timer frequency. It is customary
to have the timer interrupt run at 1000 Hz but 100 Hz may be more
@@ -19,11 +20,18 @@ choice
config HZ_100
bool "100 HZ"
help
+ 100 Hz is a suitable choice in combination with MuQSS which does
+ not rely on ticks for rescheduling interrupts, and is not Hz limited
+ for timeouts and sleeps from both the kernel and userspace.
+ This allows us to benefit from the lower overhead and higher
+ throughput of fewer timer ticks.
+
+ Non-MuQSS kernels:
100 Hz is a typical choice for servers, SMP and NUMA systems
with lots of processors that may show reduced performance if
too many timer interrupts are occurring.
- config HZ_250
+ config HZ_250_NODEF
bool "250 HZ"
help
250 Hz is a good compromise choice allowing server performance
@@ -31,7 +39,10 @@ choice
on SMP and NUMA systems. If you are going to be using NTSC video
or multimedia, selected 300Hz instead.
- config HZ_300
+ 250 Hz is the default choice for the mainline scheduler but not
+ advantageous in combination with MuQSS.
+
+ config HZ_300_NODEF
bool "300 HZ"
help
300 Hz is a good compromise choice allowing server performance
@@ -39,7 +50,7 @@ choice
on SMP and NUMA systems and exactly dividing by both PAL and
NTSC frame rates for video and multimedia work.
- config HZ_1000
+ config HZ_1000_NODEF
bool "1000 HZ"
help
1000 Hz is the preferred choice for desktop systems and other
@@ -50,9 +61,9 @@ endchoice
config HZ
int
default 100 if HZ_100
- default 250 if HZ_250
- default 300 if HZ_300
- default 1000 if HZ_1000
+ default 250 if HZ_250_NODEF
+ default 300 if HZ_300_NODEF
+ default 1000 if HZ_1000_NODEF
config SCHED_HRTICK
def_bool HIGH_RES_TIMERS
--
2.11.0
|
