sched: Fix update_cfs_load() synchronization

Using cfs_rq->nr_running is not sufficient to synchronize update_cfs_load with
the put path since nr_running accounting occurs at deactivation.

It's also not safe to make the removal decision based on load_avg as this fails
with both high periods and low shares.  Resolve this by clipping history after
4 periods without activity.

Note: the above will always occur from update_shares() since in the
last-task-sleep-case that task will still be cfs_rq->curr when update_cfs_load
is called.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101115234937.933428187@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 6268d2dc9a91..dadab4d13875 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -355,7 +355,7 @@ struct cfs_rq {
 
 	u64 load_avg;
 	u64 load_period;
-	u64 load_stamp;
+	u64 load_stamp, load_last;
 
 	unsigned long load_contribution;
 #endif