From: Vincent Guittot <vincent.guittot@linaro.org>
To: 王贇 <yun.wang@linux.alibaba.com>
Cc: Ben Segall <bsegall@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mel Gorman <mgorman@suse.de>,
"open list:SCHEDULER" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] sched: fix the nonsense shares when load of cfs_rq is too, small
Date: Fri, 6 Mar 2020 09:04:45 +0100 [thread overview]
Message-ID: <CAKfTPtD+He8UULUavz0csUeUV3TBdjShV9kUPQY6rpLswUAm4g@mail.gmail.com> (raw)
In-Reply-To: <12f79b83-491c-4b4b-0581-d23bdcec7c0c@linux.alibaba.com>
On Fri, 6 Mar 2020 at 05:23, 王贇 <yun.wang@linux.alibaba.com> wrote:
>
>
>
> On 2020/3/5 下午3:53, Vincent Guittot wrote:
> > On Thu, 5 Mar 2020 at 02:14, 王贇 <yun.wang@linux.alibaba.com> wrote:
> [snip]
> >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >>> index fcc968669aea..6d7a9d72d742 100644
> >>> --- a/kernel/sched/fair.c
> >>> +++ b/kernel/sched/fair.c
> >>> @@ -3179,9 +3179,9 @@ static long calc_group_shares(struct cfs_rq *cfs_rq)
> >>> long tg_weight, tg_shares, load, shares;
> >>> struct task_group *tg = cfs_rq->tg;
> >>>
> >>> - tg_shares = READ_ONCE(tg->shares);
> >>> + tg_shares = scale_load_down(READ_ONCE(tg->shares));
> >>>
> >>> - load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
> >>> + load = max(cfs_rq->load.weight, scale_load(cfs_rq->avg.load_avg));
> >>>
> >>> tg_weight = atomic_long_read(&tg->load_avg);
> >>
> >> Get the point, but IMHO fix scale_load_down() sounds better, to
> >> cover all the similar cases, let's first try that way see if it's
> >> working :-)
> >
> > The problem with this solution is that the avg.load_avg of gse or
> > cfs_rq might stay to 0 because it uses
> > scale_load_down(se/cfs_rq->load.weight)
>
> Will cfs_rq->load.weight be zero too without scale down?
cfs_rq->load.weight will never be 0, it's min is 2
>
> If cfs_rq->load.weight got at least something, the load will not be
> zero after pick the max, correct?
But the cfs_rq->avg.load_avg will never be other than 0 what ever
there are heavy or light tasks in the group
>
> Regards,
> Michael Wang
>
> >
> >>
> >> Regards,
> >> Michael Wang
> >>
> >>>
> >>>
> >>>
next prev parent reply other threads:[~2020-03-06 8:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 14:17 [RFC PATCH] sched: fix the nonsense shares when load of cfs_rq is too, small 王贇
2020-03-03 19:52 ` Peter Zijlstra
2020-03-04 1:19 ` 王贇
2020-03-04 8:47 ` Vincent Guittot
2020-03-04 9:43 ` Vincent Guittot
2020-03-05 1:23 ` 王贇
2020-03-04 9:52 ` Peter Zijlstra
2020-03-04 11:55 ` Vincent Guittot
2020-03-05 1:08 ` 王贇
2020-03-04 8:45 ` Vincent Guittot
2020-03-04 18:47 ` bsegall
2020-03-05 1:14 ` 王贇
2020-03-05 7:53 ` Vincent Guittot
2020-03-06 4:23 ` 王贇
2020-03-06 8:04 ` Vincent Guittot [this message]
2020-03-06 9:34 ` 王贇
2020-03-06 19:17 ` bsegall
2020-03-09 11:15 ` Vincent Guittot
2020-03-10 3:42 ` 王贇
2020-03-10 7:57 ` Vincent Guittot
2020-03-10 8:15 ` 王贇
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