linux-kernel - Re: [PATCH] cpufreq: schedutil: Don't skip freq update when limits change

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Message-ID: <CAJZ5v0gRRC3pzgDzp-FDuFtFKWE_9=1DKNTmWa-aR_bW6J14xg@mail.gmail.com>
Date:   Tue, 23 Jul 2019 11:13:17 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Doug Smythies <dsmythies@...us.net>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        "v4 . 18+" <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: schedutil: Don't skip freq update when limits change

On Tue, Jul 23, 2019 at 9:10 AM Doug Smythies <dsmythies@...us.net> wrote:
>
> On 2019.07.21 23:52 Viresh Kumar wrote:
>
> > To avoid reducing the frequency of a CPU prematurely, we skip reducing
> > the frequency if the CPU had been busy recently.
> >
> > This should not be done when the limits of the policy are changed, for
> > example due to thermal throttling. We should always get the frequency
> > within limits as soon as possible.
> >
> > Fixes: ecd288429126 ("cpufreq: schedutil: Don't set next_freq to UINT_MAX")
> > Cc: v4.18+ <stable@...r.kernel.org> # v4.18+
> > Reported-by: Doug Smythies <doug.smythies@...il.com>
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> > @Doug: Please try this patch, it must fix the issue you reported.
>
> It fixes the driver = acpi-cpufreq ; governor = schedutil test case
> It does not fix the driver = intel_cpufreq ; governor = schedutil test case

So what's the difference between them, with the patch applied?

> I have checked my results twice, but will check again in the day or two.

OK, thanks!