sched: Add support for unthrottling group entities

At the start of each period we refresh the global bandwidth pool.  At this time
we must also unthrottle any cfs_rq entities who are now within bandwidth once
more (as quota permits).

Unthrottled entities have their corresponding cfs_rq->throttled flag cleared
and their entities re-enqueued.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110721184757.574628950@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 044260a..4bbabc2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9192,6 +9192,9 @@
 		raw_spin_lock_irq(&rq->lock);
 		cfs_rq->runtime_enabled = runtime_enabled;
 		cfs_rq->runtime_remaining = 0;
+
+		if (cfs_rq_throttled(cfs_rq))
+			unthrottle_cfs_rq(cfs_rq);
 		raw_spin_unlock_irq(&rq->lock);
 	}
 out_unlock: