linux-kernel - Re: [PATCH v5 7/7] sched/fair: Add latency list

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Message-ID: <9d06c9ce-d4b3-23a8-9f9c-c1054de1aeb5@arm.com>
Date:   Wed, 26 Oct 2022 12:44:16 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>,
        Youssef Esmat <youssefesmat@...omium.org>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        linux-kernel@...r.kernel.org, parth@...ux.ibm.com,
        qais.yousef@....com, chris.hyser@...cle.com,
        valentin.schneider@....com, patrick.bellasi@...bug.net,
        David.Laight@...lab.com, pjt@...gle.com, pavel@....cz,
        tj@...nel.org, qperret@...gle.com, tim.c.chen@...ux.intel.com,
        joshdon@...gle.com, timj@....org, joel@...lfernandes.org
Subject: Re: [PATCH v5 7/7] sched/fair: Add latency list

On 12/10/2022 17:21, Vincent Guittot wrote:
> Le mardi 11 oct. 2022 ï¿½ 18:54:27 (-0500), Youssef Esmat a ï¿½crit :
>> Hi Vincent,
>>
>> On Tue, Oct 11, 2022 at 12:10 PM Vincent Guittot
>> <vincent.guittot@...aro.org> wrote:

[...]

> @@ -10894,12 +10898,17 @@ static int cpu_idle_write_s64(struct cgroup_subsys_state *css,
>  static s64 cpu_latency_nice_read_s64(struct cgroup_subsys_state *css,
>  				    struct cftype *cft)
>  {
> +	unsigned long period = sysctl_sched_latency;
>  	int last_delta = INT_MAX;
>  	int prio, delta;
>  	s64 weight;
>  
> +	if (sched_feat(GENTLE_FAIR_SLEEPERS))
> +		period >>= 1;
> +
>  	weight = css_tg(css)->latency_offset * NICE_LATENCY_WEIGHT_MAX;
> -	weight = div_s64(weight, sysctl_sched_latency);
> +	period = sysctl_sched_latency;

Looks like this line is wrong here, period has been set already for
GENTLE_FAIR_SLEEPERS and !GENTLE_FAIR_SLEEPERS?

> +	weight = div_s64(weight, period);
>  
>  	/* Find the closest nice value to the current weight */
>  	for (prio = 0; prio < ARRAY_SIZE(sched_latency_to_weight); prio++) {

[...]