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Subject: Re: [PATCH] sched/fair: Ensure _sum and _avg values stay consistent
From:   Sachin Sant <sachinp@linux.vnet.ibm.com>
In-Reply-To: <CAFpoUr1mpErE1Soa05p36wL1uTeojQ2mqNLJ1GKVnpJ+x-3itw@mail.gmail.com>
Date:   Thu, 1 Jul 2021 17:15:31 +0530
Cc:     Vincent Guittot <vincent.guittot@linaro.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Ingo Molnar <mingo@redhat.com>,
        open list <linux-kernel@vger.kernel.org>
Message-Id: <C253482E-0B1E-4F38-92D6-6F00AFFA7DEF@linux.vnet.ibm.com>
References: <20210624111815.57937-1-odin@uged.al>
 <E16E71B3-E941-4522-AFF1-ABDF918FED19@linux.vnet.ibm.com>
 <20210701103448.GL3840@techsingularity.net>
 <CAFpoUr1mpErE1Soa05p36wL1uTeojQ2mqNLJ1GKVnpJ+x-3itw@mail.gmail.com>
To:     Odin Ugedal <odin@uged.al>,
        Mel Gorman <mgorman@techsingularity.net>
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> On 01-Jul-2021, at 4:39 PM, Odin Ugedal <odin@uged.al> wrote:
>=20
> tor. 1. jul. 2021 kl. 12:34 skrev Mel Gorman <mgorman@techsingularity.net=
>:
>>=20
>> What was HEAD when you checked this? 1c35b07e6d39 was merged in the
>> 5.14-rc1 merge window so would not be in 5.13.
>=20
> 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.
>=20
Sorry about the confusion. Yes I am using this code level.

commit dbe69e43372212527abf48609aba7fc39a6daa27 (HEAD -> master, origin/mas=
ter, 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/
>=20
> while
> https://lore.kernel.org/lkml/20210623071935.GA29143@vingu-book/
> might also help in some cases as well.
>=20
> Both of those are needed to make sure that *_avg is zero whenever *_sum i=
s zero.

Okay, so additional patches are required to fix this problem completely.
I can help test these.

Thanks
-Sachin