sched: Push put_prev_task() into pick_next_task()

In order to avoid having to do put/set on a whole cgroup hierarchy
when we context switch, push the put into pick_next_task() so that
both operations are in the same function. Further changes then allow
us to possibly optimize away redundant work.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index 516c3d9ceea1..e5c922ac40ce 100644
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -33,8 +33,12 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl
         resched_task(rq->idle);
 }
 
-static struct task_struct *pick_next_task_idle(struct rq *rq)
+static struct task_struct *
+pick_next_task_idle(struct rq *rq, struct task_struct *prev)
 {
+        if (prev)
+                prev->sched_class->put_prev_task(rq, prev);
+
         schedstat_inc(rq, sched_goidle);
 #ifdef CONFIG_SMP
         /* Trigger the post schedule to do an idle_enter for CFS */