linux-kernel - Re: [PATCH v3] sched: Consolidate cpufreq updates

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Message-ID: <9e845146-8a31-407c-a5ee-e2e32f1655e5@arm.com>
Date: Mon, 13 May 2024 14:43:55 +0200
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Qais Yousef <qyousef@...alina.io>, "Rafael J. Wysocki"
 <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>,
 Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Juri Lelli <juri.lelli@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
 Mel Gorman <mgorman@...e.de>, Daniel Bristot de Oliveira
 <bristot@...hat.com>, Valentin Schneider <vschneid@...hat.com>,
 Christian Loehle <christian.loehle@....com>, linux-pm@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] sched: Consolidate cpufreq updates

On 12/05/2024 21:00, Qais Yousef wrote:

[...]

> @@ -4682,7 +4659,7 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
>  
>  	add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
>  
> -	cfs_rq_util_change(cfs_rq, 0);
> +	cpufreq_update_util(rq_of(cfs_rq), 0);

Isn't this slighlty different now?

before:

   if (&rq->cfs == cfs_rq) {
       cpufreq_update_util(rq, ....)
   }

now:

   cpufreq_update_util(rq_of(cfs_rq), ...)

You should get way more updates from attach/detach now.

>  
>  	trace_pelt_cfs_tp(cfs_rq);
>  }

[...]