linux-kernel - Re: [RFC PATCH v3 0/6] sched/cpufreq: Make schedutil energy aware

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Date:   Thu, 17 Oct 2019 12:11:16 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Douglas Raillard <douglas.raillard@....com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        mingo@...hat.com, rjw@...ysocki.net, viresh.kumar@...aro.org,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, qperret@...rret.net,
        patrick.bellasi@...bug.net, dh.han@...sung.com
Subject: Re: [RFC PATCH v3 0/6] sched/cpufreq: Make schedutil energy aware

On Thursday 17 Oct 2019 at 11:50:15 (+0200), Peter Zijlstra wrote:
> Now, the thing is, we use map_util_freq() in more places, and should we
> not reflect this increase in C for all of them? That is, why is this
> patch changing get_next_freq() and not map_util_freq().
> 
> I don't think that question is answered in the Changelogs.
> 
> Exactly because it does change the energy consumption (it must) should
> that not also be reflected in the EAS logic?

Right that shouldn't hurt and keep things consistent. That probably
won't have a huge impact in practice (the boost should be != 0 only when
the util signals haven't converged IIUC, which is a case where the EAS
calculation is already 'wrong' anyway), but that still feels like the
right thing to do.

> I'm still thinking about the exact means you're using to raise C; that
> is, the 'util - util_est' as cost_margin. It hurts my brain still.

+1 ...

Thanks,
Quentin