linux-kernel - Re: [RFC PATCH v2 0/5] sched/cpufreq: Make schedutil energy aware

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Message-ID: <20190702154422.GV3436@hirez.programming.kicks-ass.net>
Date:   Tue, 2 Jul 2019 17:44:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Douglas RAILLARD <douglas.raillard@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        mingo@...hat.com, rjw@...ysocki.net, viresh.kumar@...aro.org,
        quentin.perret@....com, patrick.bellasi@....com,
        dietmar.eggemann@....com
Subject: Re: [RFC PATCH v2 0/5] sched/cpufreq: Make schedutil energy aware

On Thu, Jun 27, 2019 at 06:15:58PM +0100, Douglas RAILLARD wrote:
> Make schedutil cpufreq governor energy-aware.
> 
> - patch 1 introduces a function to retrieve a frequency given a base
>   frequency and an energy cost margin.
> - patch 2 links Energy Model perf_domain to sugov_policy.
> - patch 3 updates get_next_freq() to make use of the Energy Model.

> 
> 1) Selecting the highest possible frequency for a given cost. Some
>    platforms can have lower frequencies that are less efficient than
>    higher ones, in which case they should be skipped for most purposes.
>    They can still be useful to give more freedom to thermal throttling
>    mechanisms, but not under normal circumstances.
>    note: the EM framework will warn about such OPPs "hertz/watts ratio
>    non-monotonically decreasing"

Humm, for some reason I was thinking we explicitly skipped those OPPs
and they already weren't used.

This isn't in fact so, and these first few patches make it so?