linux-kernel - Re: [PATCH v5 10/14] sched/cpufreq: Refactor the utilization aggregation method

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Message-ID: <CAJZ5v0j=EYnANGAj9bd44eeux1eCfeMtdn9npe5pSAzE8EVKaA@mail.gmail.com>
Date:   Wed, 1 Aug 2018 09:32:49 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Saravana Kannan <skannan@...eaurora.org>,
        Quentin Perret <quentin.perret@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Chris Redpath <chris.redpath@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Valentin Schneider <valentin.schneider@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Thara Gopinath <thara.gopinath@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Steve Muckle <smuckle@...gle.com>, adharmap@...cinc.com,
        skannan@...cinc.com, Pavan Kondeti <pkondeti@...eaurora.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        currojerez@...eup.net, Javi Merino <javi.merino@...nel.org>,
        linux-pm-owner@...r.kernel.org
Subject: Re: [PATCH v5 10/14] sched/cpufreq: Refactor the utilization
 aggregation method

On Tue, Jul 31, 2018 at 9:31 PM,  <skannan@...eaurora.org> wrote:
> On 2018-07-31 00:59, Quentin Perret wrote:
>>
>> On Monday 30 Jul 2018 at 12:35:27 (-0700), skannan@...eaurora.org wrote:
>> [...]
>>>
>>> If it's going to be a different aggregation from what's done for
>>> frequency
>>> guidance, I don't see the point of having this inside schedutil. Why not
>>> keep it inside the scheduler files?
>>
>>
>> This code basically results from a discussion we had with Peter on v4.
>> Keeping everything centralized can make sense from a maintenance
>> perspective, I think. That makes it easy to see the impact of any change
>> to utilization signals for both EAS and schedutil.
>
>
> In that case, I'd argue it makes more sense to keep the code centralized in
> the scheduler. The scheduler can let schedutil know about the utilization
> after it aggregates them. There's no need for a cpufreq governor to know
> that there are scheduling classes or how many there are. And the scheduler
> can then choose to aggregate one way for task packing and another way for
> frequency guidance.

Also the aggregate utilization may be used by cpuidle governors in
principle to decide how deep they can go with idle state selection.