linux-kernel - Re: [PATCH v4] sched/freq: move call to cpufreq_update

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Message-ID: <20191115105110.GG4131@hirez.programming.kicks-ass.net>
Date:   Fri, 15 Nov 2019 11:51:10 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mel Gorman <mgorman@...e.de>,
        Doug Smythies <dsmythies@...us.net>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sargun Dhillon <sargun@...gun.me>, Tejun Heo <tj@...nel.org>,
        Xie XiuQi <xiexiuqi@...wei.com>, xiezhipeng1@...wei.com,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v4] sched/freq: move call to cpufreq_update_util

On Fri, Nov 15, 2019 at 11:46:01AM +0100, Vincent Guittot wrote:
> On Fri, 15 Nov 2019 at 11:37, Peter Zijlstra <peterz@...radead.org> wrote:

> > Sure, but then it can still remember the value passed in last and use
> > that state later.
> >
> > It doesn't _have_ to completely discard values.
> 
> yes but it means that we run at the "wrong" frequency during this
> period and also that the cpufreq must in this case set a kind of timer
> to resubmit a new frequency change out of scheduler event

But if, as you say, we're completely shutting down the event stream
when everything has decayed, that's still true, right?