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Date:   Fri, 5 May 2023 20:16:31 +0200
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Subject: Re: [PATCH 1/1] sched: Consider CPU contention in frequency &
 load-balance busiest CPU selection
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To:     Vincent Guittot <vincent.guittot@linaro.org>
Cc:     Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Qais Yousef <qyousef@layalina.io>,
        Kajetan Puchalski <kajetan.puchalski@arm.com>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Vincent Donnefort <vdonnefort@google.com>,
        Quentin Perret <qperret@google.com>,
        Abhijeet Dharmapurikar <adharmap@quicinc.com>,
        linux-kernel@vger.kernel.org
References: <20230406155030.1989554-1-dietmar.eggemann@arm.com>
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 <CAKfTPtBcT8KbH=r2zCgqBF7V7cp=REceiyWWjjCc8FD2btO-=A@mail.gmail.com>
From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
In-Reply-To: <CAKfTPtBcT8KbH=r2zCgqBF7V7cp=REceiyWWjjCc8FD2btO-=A@mail.gmail.com>
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On 05/05/2023 10:22, Vincent Guittot wrote:
> On Thu, 4 May 2023 at 19:11, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>>
>> On 03/05/2023 18:08, Vincent Guittot wrote:
>>> On Thu, 6 Apr 2023 at 17:50, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:

[...]

>>>> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
>>>> index e3211455b203..728b186cd367 100644
>>>> --- a/kernel/sched/cpufreq_schedutil.c
>>>> +++ b/kernel/sched/cpufreq_schedutil.c
>>>> @@ -158,7 +158,8 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu)
>>>>         struct rq *rq = cpu_rq(sg_cpu->cpu);
>>>>
>>>>         sg_cpu->bw_dl = cpu_bw_dl(rq);
>>>> -       sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
>>>> +       sg_cpu->util = effective_cpu_util(sg_cpu->cpu,
>>>> +                                         cpu_boosted_util_cfs(sg_cpu->cpu),
>>>
>>> Shouldn't we have a similar change in feec to estimate correctly which
>>> OPP/ freq will be selected by schedutil ?
>>
>> Yes, this should be more correct. Schedutil and EAS should see the world
>> the same way.
>>
>> But IMHO only for the
>>
>> find_energy_efficient_cpu()
>>   compute_energy()
>>     eenv_pd_max_util()
>>       util = cpu_util_next(..., p, ...)
>>       effective_cpu_util(..., util, FREQUENCY_UTIL, ...)
>>                                     ^^^^^^^^^^^^^^
> yes only to get same max utilization and as a result the same OPP as schedutil
> 
>> case.
>>
>> Not sure what I do for the task contribution? We use
>> task_util(p)/_task_util_est(p) inside cpu_util_next().
>> Do I have to consider p->se.avg.runnable_avg as well?
> 
> hmm, I would stay with util_avg for now

OK, in this case I'm trying  to refactor cpu_util_next() so that
cpu_util_cfs() can call it as well. This will allow me to code the
runnable boosting only once in cpu_util_next().
Boosting can then be enabled via an additional `int boost` parameter for
cpu_util_next() and cpu_util_cfs().