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Message-ID: <CAKfTPtCTMFN2Hed9Ku=VLH2Uwm4sC1kBBa5yRbb20r0o=-R7jw@mail.gmail.com>
Date:   Fri, 8 Jun 2018 14:48:11 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Juri Lelli <juri.lelli@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        viresh kumar <viresh.kumar@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Quentin Perret <quentin.perret@....com>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v6 06/11] cpufreq/schedutil: use dl utilization tracking

On 8 June 2018 at 14:39, Juri Lelli <juri.lelli@...hat.com> wrote:
> Hi Vincent,
>
> On 08/06/18 14:09, Vincent Guittot wrote:
>> Now that we have both the dl class bandwidth requirement and the dl class
>> utilization, we can detect when CPU is fully used so we should run at max.
>> Otherwise, we keep using the dl bandwidth requirement to define the
>> utilization of the CPU
>>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
>> ---
>
> [...]
>
>> @@ -190,20 +192,24 @@ static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
>>       if (rq->rt.rt_nr_running)
>>               return sg_cpu->max;
>>
>> -     util = sg_cpu->util_dl;
>> -     util += sg_cpu->util_cfs;
>> +     util = sg_cpu->util_cfs;
>>       util += sg_cpu->util_rt;
>>
>> +     if ((util + sg_cpu->util_dl) >= sg_cpu->max)
>> +             return sg_cpu->max;
>> +
>
> Mmm, won't we run at max (or reach max) with a, say, 100ms/500ms DL task
> running alone?

not for a 100ms running task. You have to run more than 320ms to reach max value

100ms/500ms will vary between 0 and 907

Vincent

>
> Best,
>
> - Juri

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