tree b9a2b381becf13e620ba794e81bbd81022d93904
parent 33c3d6c61debcc0d295fe65521cfbc45409936c7
author Steven Rostedt <srostedt@redhat.com> 1291652910 -0500
committer Steven Rostedt <rostedt@goodmis.org> 1292288115 -0500

sched: Change pick_next_task_rt from unlikely to likely

The if (unlikely(!rt_rq->rt_nr_running)) test in pick_next_task_rt()
tests if there is another rt task ready to run. If so, then pick it.

In most systems, only one RT task runs at a time most of the time.
Running the branch unlikely annotator profiler on a system doing average
work "running firefox, evolution, xchat, distcc builds, etc", it showed the
following:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
  324344 135104992  99 _pick_next_task_rt             sched_rt.c           1064

99% of the time the condition is true. When an RT task schedules out,
it is unlikely that another RT task is waiting to run on that same run queue.

Simply remove the unlikely() condition.

Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc:Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>