linux-kernel - Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins

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Message-ID: <20230908141105.ofoht5z66sm6mmq2@airbuntu>
Date:   Fri, 8 Sep 2023 15:11:05 +0100
From:   Qais Yousef <qyousef@...alina.io>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Lukasz Luba <lukasz.luba@....com>
Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins

On 09/08/23 15:59, Peter Zijlstra wrote:
> On Fri, Sep 08, 2023 at 02:33:36PM +0100, Qais Yousef wrote:
> 
> > > (even hardware has these things today, we get 0-255 values that do
> > > 'something' uarch specific)
> > 
> > Ah, could I get some pointers please?
> 
> Intel HWP.EPP and AMD CPPC EPP I think.. both intel-pstate and
> amd-pstate have EPP thingies.

Okay, thanks!

So do you see tying this to the presence of some hardware mechanisms and
provide a fallback for the other systems to define it somehow would be the best
way to explore this?


Cheers

--
Qais Yousef