linux-kernel - Re: [PATCH 1/2] sched/schedutil: rework performance estimation

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Date:   Fri, 13 Oct 2023 20:20:58 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        rafael@...nel.org, viresh.kumar@...aro.org, qyousef@...alina.io,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        lukasz.luba@....com
Subject: Re: [PATCH 1/2] sched/schedutil: rework performance estimation


* Vincent Guittot <vincent.guittot@...aro.org> wrote:

> +
> +	/* The minimum utilization returns the highest level between:
> +	 * - the computed DL bandwidth needed with the irq pressure which
> +	 *   steals time to the deadline task.
> +	 * - The minimum bandwidth requirement for CFS.
> +	 */

Nit: please use the standard multi-line Linux kernel comment style.

> +	/* The maximum hint is a soft bandwidth requirement which can be lower
> +	 * than the actual utilization because of max uclamp requirments
>  	 */

Ditto.

> +unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
> +				 unsigned long min,
> +				 unsigned long max)
> +{
> +	unsigned long target;
> +	struct rq *rq = cpu_rq(cpu);
> +
> +	if (rt_rq_is_runnable(&rq->rt))
> +		return max;
> +
> +	/* Provide at least enough capacity for DL + irq */
> +	target =  min;

s/  / /
s/irq/IRQ/

Thanks,

	Ingo