linux-kernel - Re: [PATCH v2 3/3] PM / EM: Skip inefficient OPPs

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Message-ID: <20210601091352.7tthvv6hygtisprm@vireshk-i7>
Date:   Tue, 1 Jun 2021 14:43:52 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     Vincent Donnefort <vincent.donnefort@....com>,
        Peter Zijlstra <peterz@...radead.org>, rjw@...ysocki.net,
        vincent.guittot@...aro.org, linux-kernel@...r.kernel.org,
        ionela.voinescu@....com, lukasz.luba@....com,
        dietmar.eggemann@....com
Subject: Re: [PATCH v2 3/3] PM / EM: Skip inefficient OPPs

On 01-06-21, 09:07, Quentin Perret wrote:
> Just to reiterate here what was discussed on IRC the other day, I still
> feel that the choice of an efficient OPP or not is a policy decision,
> and should be left to the governor.

I agree. cpufreq core shouldn't always do this.

> It's not obvious to me that the userspace govenor for instance wants any
> of this. Same thing with e.g. the powersave governor if the lowest OPPs
> are inefficient (yes skipping them will not impact energy, but it will
> impact instantaneous power).

Yes, these governors shouldn't end up using the efficient only stuff.

> So if we're going to move that logic to the cpufreq core, then we'll
> probably want two separate APIs and make sure to use the effiency-aware
> one is used only from the places where that makes sense.

Yeah, we need another API or parameter "bool efficient" or something.

-- 
viresh