From: Steven Rostedt Date: Mon, 6 Dec 2010 22:10:31 +0000 (-0500) Subject: sched: Remove unlikely() from ttwu_post_activation X-Git-Tag: v3.1-rc1~298^2~19^2 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=e69c634190dc724ef2d845ace8d783031d3e492e sched: Remove unlikely() from ttwu_post_activation The unlikely() used in ttwu_post_activation() tests if the rq->idle_stamp is set. But since this is for a wakeup, and wakeups happen when tasks block on IO, and blocking tasks on IO may put the system into idle, this can actually be a common occurence. Running the annotated branch profiler on an average desktop running firefox, evolution, xchat and distcc, the report shows: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 34884862 146110926 80 ttwu_post_activation sched.c 2309 80% of the time, this unlikely is incorrect. Best not to assume what the result is, and just remove the branch annotation. Cc: Peter Zijlstra Signed-off-by: Steven Rostedt --- diff --git a/kernel/sched.c b/kernel/sched.c index 269a0450281c..6d24b2e8d82d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2458,7 +2458,7 @@ static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq, if (p->sched_class->task_woken) p->sched_class->task_woken(rq, p); - if (unlikely(rq->idle_stamp)) { + if (rq->idle_stamp) { u64 delta = rq->clock - rq->idle_stamp; u64 max = 2*sysctl_sched_migration_cost;