linux-kernel - Re: [PATCH v2 0/3] Add basic tracing for uclamp and schedutil

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Message-ID: <CAJZ5v0juOwCHNoCo8gX+NopuzK18d+v3QV0qkGcg1BvDVcPpKQ@mail.gmail.com>
Date:   Mon, 22 May 2023 16:40:00 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>, rostedt@...dmis.org,
        mhiramat@...nel.org, mingo@...hat.com, peterz@...radead.org,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, delyank@...com,
        qyousef@...gle.com, qyousef@...alina.io,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] Add basic tracing for uclamp and schedutil

Hi Lukasz,

On Mon, May 22, 2023 at 3:38 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> Hi Rafael,
>
>
>
> On 5/9/23 13:22, Lukasz Luba wrote:
> > Hi all,
> >
> > The task scheduler feature: Uclamp, begins to take off. To better understand
> > the dynamics in the task scheduler and CPU frequency requests we need some
> > better tracing.
> > In schedutil (cpufreq governor) we allow to enter the scheduler
> > and make the frequency change. Although, there is some limit in regards to how
> > often this can happen. That min period is provided by the cpufreq driver.
> > Thus, some of the cpufreq requests might be filter out and the frequency won't
> > be changed (hopefuly will be set a bit later). We would like to know about
> > those situations, especially in context of the user-space hints made via
> > Uclamp for particular tasks.
> > This patch set aims to add base for our toolkits and post-processing trace
> > analyzes.
>
> > Changelog:
> > v2:
> > - solved the issue from CI build warning, dropped schedutil.h and re-used
> >    the sched.h which is available in build_utility.c where cpufreq_schedutil.c
> >    is included
> > - added tag for the last patch 3/3 for the CI robot helping hend
> > - re-based on top of v6.4-rc1
> > v1:
> > - implementation can be found here [1]
> >
>
> I was going to gently ping you, while I've realized that you
> are not on CC list :( I don't know what happened, my apologies.

No worries.

> Shell I resend this patch set so you can have it in a proper way
> in your mailbox?

Well, for schedutil you should also CC linux-pm (done now), so please resend it.

> Could you have a look at this, please?

I could, but if I'm to reply, it will be much more convenient for me
if it is there in my inbox.

> This is getting more attention, since in Android we have a
> daemon which can now communicate with the kernel and send
> those Uclamp values on behalf of an unprivileged app.