linux-kernel - Re: [PATCH 4/4] cpufreq: schedutil: Don't call sugov_get

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Date:   Mon, 18 Dec 2017 19:26:21 -0800
From:   Joel Fernandes <joelaf@...gle.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...roid.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] cpufreq: schedutil: Don't call sugov_get_util() unnecessarily

On Wed, Dec 13, 2017 at 1:53 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> sugov_update_shared() may get called to clear the scheduling class flags
> and we would return immediately in that case. Calling sugov_get_util()
> in that case isn't going to be of any use then. Move invocation of
> sugov_get_util() after the clear flag is checked.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  kernel/sched/cpufreq_schedutil.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 7edfdc59ee8f..b69c37c867fe 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -349,8 +349,6 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
>         unsigned long util, max;
>         unsigned int next_f;
>
> -       sugov_get_util(&util, &max, sg_cpu->cpu);
> -
>         raw_spin_lock(&sg_policy->update_lock);
>
>         if (unlikely(flags & SCHED_CPUFREQ_CLEAR)) {
> @@ -358,6 +356,8 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
>                 goto unlock;
>         }
>
> +       sugov_get_util(&util, &max, sg_cpu->cpu);
> +
>         sg_cpu->util = util;

Reviewed-by: Joel Fernandes <joelaf@...gle.com>

Thanks,

- Joel