diff options
| author | Alex Shi <alex.shi@intel.com> | 2013-06-20 10:18:48 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-06-27 10:07:32 +0200 |
| commit | 282cf499f03ec1754b6c8c945c9674b02631fb0f (patch) | |
| tree | a3f0c1ad7b760cf327ff566aa90efc41b71d3c4b /kernel | |
| parent | a75cdaa915e42ef0e6f38dc7f2a6a1deca91d648 (diff) | |
sched: Fix sleep time double accounting in enqueue entity
The woken migrated task will __synchronize_entity_decay(se); in
migrate_task_rq_fair, then it needs to set
`se->avg.last_runnable_update -= (-se->avg.decay_count) << 20' before
update_entity_load_avg, in order to avoid sleep time is updated twice
for se.avg.load_avg_contrib in both __syncchronize and
update_entity_load_avg.
However if the sleeping task is woken up from the same cpu, it miss
the last_runnable_update before update_entity_load_avg(se, 0, 1), then
the sleep time was used twice in both functions. So we need to remove
the double sleep time accounting.
Paul also contributed some code comments in this commit.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1371694737-29336-5-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e1602a0fdbf8..9bbc303598ea 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1571,7 +1571,13 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, } wakeup = 0; } else { - __synchronize_entity_decay(se); + /* + * Task re-woke on same cpu (or else migrate_task_rq_fair() + * would have made count negative); we must be careful to avoid + * double-accounting blocked time after synchronizing decays. + */ + se->avg.last_runnable_update += __synchronize_entity_decay(se) + << 20; } /* migrated tasks did not contribute to our blocked load */ |