[PATCH] sched: minor optimization

[Nikanth Karthikesan <knikanth@suse.de>]

As an optimization, if all tasks are in the fair class, the next task is
directly picked from fair_sched_class. But, if it returns no task we go
through again from sched_class_highest which could be avoided and
instead return the idle task directly.


Signed-off-by : Nikanth Karthikesan <knikanth@suse.de>
---
 kernel/sched.c |    2 ++
 1 file changed, 2 insertions(+)

Index: b/kernel/sched.c
===================================================================
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3449,6 +3449,8 @@ pick_next_task(struct rq *rq, struct tas
 		p = fair_sched_class.pick_next_task(rq);
 		if (likely(p))
 			return p;
+		else /* rq->nr_running is zero */
+			return idle_sched_class.pick_next_task(rq);
 	}

 	class = sched_class_highest;