linux-kernel - Re: [RFC PATCH 0/1] sched/pelt: Change PELT halflife at runtime

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Message-ID: <YzV/yT6OYMgaq0kD@hirez.programming.kicks-ass.net>
Date:   Thu, 29 Sep 2022 13:21:45 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Kajetan Puchalski <kajetan.puchalski@....com>
Cc:     Jian-Min Liu <jian-min.liu@...iatek.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Vincent Donnefort <vdonnefort@...gle.com>,
        Quentin Perret <qperret@...gle.com>,
        Patrick Bellasi <patrick.bellasi@...bug.net>,
        Abhijeet Dharmapurikar <adharmap@...cinc.com>,
        Qais Yousef <qais.yousef@....com>,
        linux-kernel@...r.kernel.org,
        Jonathan JMChen <jonathan.jmchen@...iatek.com>
Subject: Re: [RFC PATCH 0/1] sched/pelt: Change PELT halflife at runtime

On Thu, Sep 29, 2022 at 12:10:17PM +0100, Kajetan Puchalski wrote:

> Overall, the problem being solved here is that based on our testing the
> PELT half life can occasionally be too slow to keep up in scenarios
> where many frames need to be rendered quickly, especially on high-refresh
> rate phones and similar devices.

But it is a problem of DVFS not ramping up quick enough; or of the
load-balancer not reacting to the increase in load, or what aspect
controlled by PELT is responsible for the improvement seen?