Re: [PATCH v5 6/7] sched: consider runnable load average in move_tasks

From: Alex Shi
Date: Wed May 08 2013 - 21:24:43 EST


Paul,

I am wondering if the following patch needed.
The wakeuped migrated task will __synchronize_entity_decay(se); in migrate_task_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 slept time is updated twice for
se.avg.load_avg_contrib in both __syncchronize and update_entity_load_avg.

but if the slept task is waked up from self cpu, it miss the last_runnable_update before
update_entity_load_avg(se, 0, 1), so the slept time was used twice in both functions.
Is that right?

Regards
Alex
---
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a80ae94..1b49e97 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1532,7 +1532,8 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
}
wakeup = 0;
} else {
- __synchronize_entity_decay(se);
+ se->avg.last_runnable_update += __synchronize_entity_decay(se)
+ << 20;
}

/* migrated tasks did not contribute to our blocked load */
if (wakeup) {
subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
update_entity_load_avg(se, 0, 1);
}


--
Thanks
Alex
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