linux-kernel - Re: [PATCH 1/2] cpufreq: schedutil: Don't restrict kthread to related

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Message-ID: <2055992.ZVNgYq5ZDC@aspire.rjw.lan>
Date:   Tue, 22 Aug 2017 15:26:42 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Juri Lelli <Juri.Lelli@....com>, joelaf@...gle.com,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily

On Thursday, August 10, 2017 6:20:55 AM CEST Viresh Kumar wrote:
> Utilization update callbacks are now processed remotely, even on the
> CPUs that don't share cpufreq policy with the target CPU (if
> dvfs_possible_from_any_cpu flag is set).
> 
> But in non-fast switch paths, the frequency is changed only from one of
> policy->related_cpus. This happens because the kthread which does the
> actual update is bound to a subset of CPUs (i.e. related_cpus).
> 
> Allow frequency to be remotely updated as well (i.e. call
> __cpufreq_driver_target()) if dvfs_possible_from_any_cpu flag is set.
> 
> Reported-by: Pavan Kondeti <pkondeti@...eaurora.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  kernel/sched/cpufreq_schedutil.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 2e74c49776be..504d0752f8f2 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -487,7 +487,11 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
>  	}
>  
>  	sg_policy->thread = thread;
> -	kthread_bind_mask(thread, policy->related_cpus);
> +
> +	/* Kthread is bound to all CPUs by default */
> +	if (!policy->dvfs_possible_from_any_cpu)
> +		kthread_bind_mask(thread, policy->related_cpus);
> +
>  	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
>  	mutex_init(&sg_policy->work_lock);
>  
> 

Applied, thanks!