linux-kernel - Re: [PATCH] sched/fair: Encapsulate set custom slice in a __setparam

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Message-ID: <20250110165828.GD4213@noisy.programming.kicks-ass.net>
Date: Fri, 10 Jan 2025 17:58:28 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: mingo@...hat.com, juri.lelli@...hat.com, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	vschneid@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/fair: Encapsulate set custom slice in a
 __setparam_fair() function

On Fri, Jan 10, 2025 at 03:46:56PM +0100, Vincent Guittot wrote:
> Similarly to dl, create a __setparam_fair() function to set parameters
> related to fair class and move it in the fair.c file.
> 
> No functional changes expected
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>

Thanks!

> @@ -5050,6 +5053,26 @@ static inline void util_est_update(struct cfs_rq *cfs_rq,
>  	trace_sched_util_est_se_tp(&p->se);
>  }
>  
> +void __setparam_fair(struct task_struct *p, const struct sched_attr *attr)
> +{
> +	struct sched_entity *se = &p->se;
> +	unsigned int util_est;
> +
> +	p->static_prio = NICE_TO_PRIO(attr->sched_nice);
> +	if (attr->sched_runtime) {
> +		se->custom_slice = 1;
> +		se->slice = clamp_t(u64, attr->sched_runtime,
> +				      NSEC_PER_MSEC/10,   /* HZ=1000 * 10 */
> +				      NSEC_PER_MSEC*100); /* HZ=100  / 10 */
> +	} else {
> +		se->custom_slice = 0;
> +		se->slice = sysctl_sched_base_slice;
> +	}
> +
> +
> +}
> +
> +

I've trimmed some of that spurious whitespace.

Also, seeing this function, I'm reminded that I used to have that clamp
conditional on !CAP_SYS_NICE -- is that something we want to put in
again?