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From:   Vincent Guittot <vincent.guittot@linaro.org>
Date:   Thu, 1 Jul 2021 19:21:18 +0200
Message-ID: <CAKfTPtBKt0Nrr79-v_HGvB-VRnsgntbX0hPx9rt_Ka_xt=RP9w@mail.gmail.com>
Subject: Re: [PATCH] sched/fair: Ensure _sum and _avg values stay consistent
To:     Sachin Sant <sachinp@linux.vnet.ibm.com>
Cc:     Odin Ugedal <odin@uged.al>,
        Mel Gorman <mgorman@techsingularity.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Ingo Molnar <mingo@redhat.com>,
        open list <linux-kernel@vger.kernel.org>
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On Thu, 1 Jul 2021 at 13:51, Sachin Sant <sachinp@linux.vnet.ibm.com> wrote:
>
>
>
> > On 01-Jul-2021, at 4:39 PM, Odin Ugedal <odin@uged.al> wrote:
> >
> > tor. 1. jul. 2021 kl. 12:34 skrev Mel Gorman <mgorman@techsingularity.net>:
> >>
> >> What was HEAD when you checked this? 1c35b07e6d39 was merged in the
> >> 5.14-rc1 merge window so would not be in 5.13.
> >
> > From the kernel log it looks like he used commit dbe69e433722
> > (somewhere in Linus' tree), and that should include my patch. I don't
> > think the patches from Vincent in the previous thread have been posted
> > properly, and I think those can fix the edge case you are seeing.
> >
> Sorry about the confusion. Yes I am using this code level.
>
> commit dbe69e43372212527abf48609aba7fc39a6daa27 (HEAD -> master, origin/master, origin/HEAD)
> Merge: a6eaf3850cb1 b6df00789e28
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date:   Wed Jun 30 15:51:09 2021 -0700
>
> This does contain the patch from Odin.
>
> > This should mitigate some issues:
> > https://lore.kernel.org/lkml/20210622143154.GA804@vingu-book/
> >
> > while
> > https://lore.kernel.org/lkml/20210623071935.GA29143@vingu-book/
> > might also help in some cases as well.
> >
> > Both of those are needed to make sure that *_avg is zero whenever *_sum is zero.
>
> Okay, so additional patches are required to fix this problem completely.
> I can help test these.

I just sent a clean version of the 1st patch :
https://lore.kernel.org/lkml/20210701171837.32156-1-vincent.guittot@linaro.org/

>
> Thanks
> -Sachin
>