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

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Message-ID: <20200626023219.wvhzomwzlw24bzrv@vireshk-i7>
Date:   Fri, 26 Jun 2020 08:02:19 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Wei Wang <wvw@...gle.com>
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 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 :)

> 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