sched: Remove unlikely() from ttwu_post_activation

From: Steven Rostedt <srostedt@redhat.com>
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: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=e69c634190dc724ef2d845ace8d783031d3e492e

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>