linux-kernel - Re: [PATCH] sched/fair: schedutil: update only with all info available

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Message-ID: <CAJWu+oo3j-i0AsbRxkp5t8aiEWQezbEQL5FmHTS1p+aUJBx77w@mail.gmail.com>
Date:   Thu, 12 Apr 2018 11:06:35 -0700
From:   Joel Fernandes <joelaf@...gle.com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Patrick Bellasi <patrick.bellasi@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steve Muckle <smuckle@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: Re: [PATCH] sched/fair: schedutil: update only with all info available

On Thu, Apr 12, 2018 at 12:01 AM, Vincent Guittot
<vincent.guittot@...aro.org> wrote:

>>
>> Also that aside, the "running util" is what was used to drive the CFS
>> util before Peter's patch (8f111bc357a). That was accounting the
>> blocked and decaying utilization but that patch changed the behavior.
>> It seems logical we should just use that not check for h_nr_running
>> for CFS so we don't miss on the decayed  utilization. What is the use
>> of checking h_nr_running or state of runqueue for CFS? I am sure to be
>> missing something here. :-(
>
> As Peter mentioned, the change in commit (8f111bc357a) was to remove
> the test that was arbitrary removing the util_avg of a cpu that has
> not been updated since a tick
>
> But with the update of blocked idle load, we don't need to handle the
> case of stalled load/utilization

Thanks a lot for the clarification. It makes sense now.

- Joel