summaryrefslogtreecommitdiffstats
path: root/kernel/sched
diff options
context:
space:
mode:
authorXunlei Pang <pang.xunlei@linaro.org>2014-12-16 23:58:29 +0800
committerIngo Molnar <mingo@kernel.org>2015-01-14 13:34:13 +0100
commit638476007d13534b2ed4134bf0279ef44071140b (patch)
treeaa8ee17a7fba6a4c80c66057b2e257568db8080e /kernel/sched
parent7f1a169b88f513e32a432ca0f85bfd282d117bd6 (diff)
downloadlinux-638476007d13534b2ed4134bf0279ef44071140b.tar.bz2
sched/fair: Fix the dealing with decay_count in __synchronize_entity_decay()
In __synchronize_entity_decay(), if "decays" happens to be zero, se->avg.decay_count will not be zeroed, holding the positive value assigned when dequeued last time. This is problematic in the following case: If this runnable task is CFS-balanced to other CPUs soon afterwards, migrate_task_rq_fair() will treat it as a blocked task due to its non-zero decay_count, thereby adding its load to cfs_rq->removed_load wrongly. Thus, we must zero se->avg.decay_count in this case as well. Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1418745509-2609-1-git-send-email-pang.xunlei@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 40667cbf371b..97000a99a293 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2574,11 +2574,11 @@ static inline u64 __synchronize_entity_decay(struct sched_entity *se)
u64 decays = atomic64_read(&cfs_rq->decay_counter);
decays -= se->avg.decay_count;
+ se->avg.decay_count = 0;
if (!decays)
return 0;
se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
- se->avg.decay_count = 0;
return decays;
}