From 317f394160e9beb97d19a84c39b7e5eb3d7815a8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 5 Apr 2011 17:23:58 +0200 Subject: sched: Move the second half of ttwu() to the remote cpu Now that we've removed the rq->lock requirement from the first part of ttwu() and can compute placement without holding any rq->lock, ensure we execute the second half of ttwu() on the actual cpu we want the task to run on. This avoids having to take rq->lock and doing the task enqueue remotely, saving lots on cacheline transfers. As measured using: http://oss.oracle.com/~mason/sembench.c $ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i; done $ echo 4096 32000 64 128 > /proc/sys/kernel/sem $ ./sembench -t 2048 -w 1900 -o 0 unpatched: run time 30 seconds 647278 worker burns per second patched: run time 30 seconds 816715 worker burns per second Reviewed-by: Frank Rowand Cc: Mike Galbraith Cc: Nick Piggin Cc: Linus Torvalds Cc: Andrew Morton Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20110405152729.515897185@chello.nl --- init/Kconfig | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index 56240e724d9a..32745bfe059e 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -827,6 +827,11 @@ config SCHED_AUTOGROUP desktop applications. Task group autogeneration is currently based upon task session. +config SCHED_TTWU_QUEUE + bool + depends on !SPARC32 + default y + config MM_OWNER bool -- cgit v1.2.3