linux-kernel - Re: [PATCH] cpufreq: schedutil: force frequency update when limits change

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Message-ID: <CAGXk5yqsj+YTv3=Dj-NZY=sBb=g9DUfVmxcO-CeE3jjipA9Osw@mail.gmail.com>
Date:   Thu, 25 Jun 2020 21:15:09 -0700
From:   Wei Wang <wvw@...gle.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Wei Wang <wei.vince.wang@...il.com>, dsmythies@...us.net,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: schedutil: force frequency update when limits change

On Thu, Jun 25, 2020 at 7:32 PM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 26-06-20, 07:44, Viresh Kumar wrote:
> > On 25-06-20, 13:47, Wei Wang wrote:
> > > On Thu, Jun 25, 2020 at 3:23 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > > > I am sorry but I am not fully sure of what the problem is. Can you
> > > > describe that by giving an example with some random frequency, and
> > > > tell the expected and actual behavior ?
> > > >
> > > The problem is sugov thought next_freq already updated (but actually
> > > skipped by the rate limit thing) and all following updates will be
> > > skipped.
>
> The rate-limiting thing is specific to android and not present in
> mainline. Even in android I see next_freq getting updated only after
> rate-limiting is verified.
>
> I think you maybe trying to fix an android only problem in mainline,
> which may not be required at all. And I am not sure if Android has a
> problem as well :)
>
Yes, that is Android specific, I added you to the Gerrit already.

Thanks!
-Wei

> > I am sorry, can you please give a detailed example with existing
> > frequency and limits, then the limits changed to new values, then what
> > exactly happens ?
> >
> > > Actually this is specifically for Android common kernel 4.19's issue
> > > which has sugov_up_down_rate_limit in sugov_update_next_freq, let's
> > > continue discussion there.
> >
> > If it is a mainline problem, we will surely get it fixed here. Just
> > that I am not able to understand the problem yet. Sorry about that.
>
> --
> viresh