Commit-ID:  abfafa54db9aba404e8e6763503f04d35bd07138
Gitweb:     http://git.kernel.org/tip/abfafa54db9aba404e8e6763503f04d35bd07138
Author:     Jason Low <[email protected]>
AuthorDate: Fri, 13 Sep 2013 11:26:51 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Fri, 20 Sep 2013 12:03:41 +0200

sched: Reduce overestimating rq->avg_idle

When updating avg_idle, if the delta exceeds some max value, then avg_idle
gets set to the max, regardless of what the previous avg was. This can cause
avg_idle to often be overestimated.

This patch modifies the way we update avg_idle by always updating it with the
function call to update_avg() first. Then, if avg_idle exceeds the max, we set
it to the max.

Signed-off-by: Jason Low <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Reviewed-by: Srikar Dronamraju <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/sched/core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5ac63c9..048f39e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1332,10 +1332,11 @@ ttwu_do_wakeup(struct rq *rq, struct task_struct *p, 
int wake_flags)
                u64 delta = rq_clock(rq) - rq->idle_stamp;
                u64 max = 2*sysctl_sched_migration_cost;
 
-               if (delta > max)
+               update_avg(&rq->avg_idle, delta);
+
+               if (rq->avg_idle > max)
                        rq->avg_idle = max;
-               else
-                       update_avg(&rq->avg_idle, delta);
+
                rq->idle_stamp = 0;
        }
 #endif
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to