linux-kernel - Re: [PATCH RESEND] cpufreq: schedutil: Use idle

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Date:   Tue, 19 Dec 2017 11:32:09 -0800
From:   Joel Fernandes <joelaf@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Chris Redpath <Chris.Redpath@....com>,
        Steve Muckle <smuckle@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Ramussen <morten.rasmussen@....com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Saravana Kannan <skannan@...cinc.com>,
        Vikram Mulukutla <markivx@...eaurora.org>,
        Rohit Jain <rohit.k.jain@...cle.com>,
        Atish Patra <atish.patra@...cle.com>,
        Josef Bacik <jbacik@...com>, Rik van Riel <riel@...hat.com>,
        EAS Dev <eas-dev@...ts.linaro.org>
Subject: Re: [PATCH RESEND] cpufreq: schedutil: Use idle_calls counter of the
 remote CPU

On Tue, Dec 19, 2017 at 10:48 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Tue, Dec 19, 2017 at 09:47:12AM -0800, Joel Fernandes wrote:
>> Since the recent remote cpufreq callback work, its possible that a cpufreq
>> update is triggered from a remote CPU. For single policies however, the current
>> code uses the local CPU when trying to determine if the remote sg_cpu entered
>> idle or is busy. This is incorrect. To remedy this, compare with the nohz tick
>> idle_calls counter of the remote CPU.
>>
>> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
>> Signed-off-by: Joel Fernandes <joelaf@...gle.com>
>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Sweet!

>
>> ---
>> Just resending this which is cpufreq-related as requested by Rafael rebased
>> on linus/master.
>>
>> The other 2 patches in my last series which can go in independent of this one are:
>> https://patchwork.kernel.org/patch/10115395/
>> https://patchwork.kernel.org/patch/10115401/
>> I'm still waiting on scheduler maintainers to comment on those. Unfortunately,
>> I haven't heard back anything yet since the last repost of those.
>
> Both of us have been somewhat preoccupied with that whole kaiser/pti
> thing the past few weeks.

I understand, thanks for taking time to look at it! Hopefully you're
Ok with the second one as well
(https://patchwork.kernel.org/patch/10115401). And this cap aware
one's been pretty beaten to death too:
https://patchwork.kernel.org/patch/10113337/ but let me know your
objections if any.

>
> I have an absolutely stupid backlog :/

I see. :/
I am thinking of spending more time reviewing fwiw and hopefully
helping relieve some of that burden. Happy to help in any other way as
well so let me/us know how we can help.

thanks,

- Joel