sched/fair: Optimize cgroup pick_next_task_fair()
Since commit 2f36825b ("sched: Next buddy hint on sleep and preempt path") it is likely we pick a new task from the same cgroup, doing a put and then set on all intermediate entities is a waste of time, so try to avoid this. Measured using: mount nodev /cgroup -t cgroup -o cpu cd /cgroup mkdir a; cd a mkdir b; cd b mkdir c; cd c echo $$ > tasks perf stat --repeat 10 -- taskset 1 perf bench sched pipe PRE : 4.542422684 seconds time elapsed ( +- 0.33% ) POST: 4.389409991 seconds time elapsed ( +- 0.32% ) Which shows a significant improvement of ~3.5% Signed-off-by:Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop Signed-off-by:
Ingo Molnar <mingo@kernel.org>
parent
f1044799
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