Re: [PATCH 05/10] sched,fair: remove cfs rqs from leaf_cfs_rq_list bottom up
From: Rik van Riel
Date: Thu Jul 04 2019 - 21:02:42 EST
On Thu, 2019-07-04 at 11:33 +0200, Vincent Guittot wrote:
> On Fri, 28 Jun 2019 at 22:49, Rik van Riel <riel@xxxxxxxxxxx> wrote:
> > Reducing the overhead of the CPU controller is achieved by not
> > walking
> > all the sched_entities every time a task is enqueued or dequeued.
> > @@ -7687,6 +7700,10 @@ static inline bool cfs_rq_is_decayed(struct
> > cfs_rq *cfs_rq)
> > if (cfs_rq->avg.util_sum)
> > return false;
> > + /* Remove decayed parents once their decayed children are
> > gone. */
> > + if (cfs_rq->children_on_list)
> I'm not sure that you really need to count whether childrens are on
> the list.
> Instead you can take advantage of the list ordering and you only have
> to test if the previous cfs_rq in the list is a child. If it's not
> then there is no more child
> and you can remove the new field children_on_list and inc/dec it
Good suggestion. I'll do that for v3.
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