linux-kernel - Re: [PATCH v3] sched/fair: Sync se's load_avg with cfs_rq in reweight

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Message-ID: <01e68be1-dc49-448c-9338-70ececd0bec7@arm.com>
Date: Mon, 29 Jul 2024 09:56:35 +0200
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Chuyi Zhou <zhouchuyi@...edance.com>, mingo@...hat.com,
 peterz@...radead.org, juri.lelli@...hat.com, vincent.guittot@...aro.org,
 rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de, vschneid@...hat.com
Cc: chengming.zhou@...ux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] sched/fair: Sync se's load_avg with cfs_rq in
 reweight_task

On 23/07/2024 13:42, Chuyi Zhou wrote:
> In reweight_task(), there are two situations:
> 
> 1. The task was on_rq, then the task's load_avg is accurate because we
> synchronized it with cfs_rq through update_load_avg() in dequeue_task().

Just asking: That's the dequeue_task() in __sched_setscheduler() or
set_user_nice()? Maybe this is worth mentioning here?

[...]

> @@ -3795,7 +3816,9 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
>  		if (!curr)
>  			__dequeue_entity(cfs_rq, se);
>  		update_load_sub(&cfs_rq->load, se->load.weight);
> -	}
> +	} else if (entity_is_task(se))
> +		sync_entity_load_avg(se);
> +

IMHO, the 'if else' path needs braces. See
Documentation/process/coding-style.rst '3) Placing Braces and Spaces'.

>  	dequeue_load_avg(cfs_rq, se);
>  
>  	if (se->on_rq) {

[...]

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>