linux-kernel - Re: [PATCH RFC 3/5] cpufreq: schedutil: Use idle

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Date:   Mon, 30 Oct 2017 14:48:29 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Joel Fernandes <joelaf@...gle.com>
Cc:     linux-kernel@...r.kernel.org,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Cc: Srinivas Pandruvada" <srinivas.pandruvada@...ux.intel.com>,
        "Cc: Len Brown" <lenb@...nel.org>,
        "Cc: Juri Lelli" <juri.lelli@....com>,
        "Cc: Patrick Bellasi" <patrick.bellasi@....com>,
        "Cc: Steve Muckle" <smuckle@...gle.com>,
        "Cc: Brendan Jackman" <brendan.jackman@....com>,
        "Cc: Chris Redpath" <Chris.Redpath@....com>,
        "Cc: Atish Patra" <atish.patra@...cle.com>,
        "Cc: Dietmar Eggemann" <dietmar.eggemann@....com>,
        "Cc: Vincent Guittot" <vincent.guittot@...aro.org>,
        "Cc: Morten Ramussen" <morten.rasmussen@....com>,
        "Cc: EAS Dev" <eas-dev@...ts.linaro.org>,
        "Cc: Android Kernel" <kernel-team@...roid.com>
Subject: Re: [PATCH RFC 3/5] cpufreq: schedutil: Use idle_calls counter of
 the remote CPU

On 28-10-17, 02:59, 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.
> 
> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>

Fixes: 674e75411fc2 ("sched: cpufreq: Allow remote cpufreq callbacks")

> Signed-off-by: Joel Fernandes <joelaf@...gle.com>
> ---
>  include/linux/tick.h             |  1 +
>  kernel/sched/cpufreq_schedutil.c |  2 +-
>  kernel/time/tick-sched.c         | 13 +++++++++++++
>  3 files changed, 15 insertions(+), 1 deletion(-)

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh