Messages in this thread | | | Date | Wed, 19 Aug 2015 00:32:43 +0800 | From | "T. Zhou" <> | Subject | Re: [PATCH v2 1/3] sched: sync a se with its cfs_rq when attaching and dettaching |
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Hi,
On Mon, Aug 17, 2015 at 04:45:50PM +0900, byungchul.park@lge.com wrote: > From: Byungchul Park <byungchul.park@lge.com> > > current code is wrong with cfs_rq's avg loads when changing a task's > cfs_rq to another. i tested with "echo pid > cgroup" and found that > e.g. cfs_rq->avg.load_avg became larger and larger whenever i changed > a cgroup to another again and again. we have to sync se's avg loads > with both *prev* cfs_rq and next cfs_rq when changing its group. >
my simple think about above, may be nothing or wrong, just ignore it.
if a load balance migration happened just before cgroup change, prev cfs_rq and next cfs_rq will be on different cpu. migrate_task_rq_fair() and update_cfs_rq_load_avg() will sync and remove se's load avg from prev cfs_rq. whether or not queued, well done. dequeue_task() decay se and pre_cfs before calling task_move_group_fair(). after set cfs_rq in task_move_group_fair(), if queued, se's load avg do not add to next cfs_rq(try set last_update_time to 0 like migration to add), if !queued, also need to add se's load avg to next cfs_rq.
if no load balance migration happened when change cgroup. prev cfs_rq and next cfs_rq may be on same cpu(not sure), this time, need to remove se's load avg by ourself, also need to add se's load avg on next cfs_rq.
thinks, -- Tao
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