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authorSteven Rostedt <srostedt@redhat.com>2010-12-06 17:10:31 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-12-13 19:56:43 -0500
commite69c634190dc724ef2d845ace8d783031d3e492e (patch)
tree03c16d8f6f3ec24408adbe9042bc42546725141a
parent63f01241176d7cbc976385aec32f0a209b0bc36a (diff)
downloadop-kernel-dev-e69c634190dc724ef2d845ace8d783031d3e492e.zip
op-kernel-dev-e69c634190dc724ef2d845ace8d783031d3e492e.tar.gz
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 <a.p.zijlstra@chello.nl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/sched.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 269a045..6d24b2e 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;
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