linux-kernel - Re: [PATCH v2 2/2] sched/dl: Remove some comments and adjust code in push_dl

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Date:   Mon, 25 Apr 2022 18:21:20 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Hao Jia <jiahao.os@...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, bristot@...hat.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] sched/dl: Remove some comments and adjust code in
 push_dl_task

On 22/04/2022 11:09, Hao Jia wrote:

Nitpick: I would change the message slightly into something like:

sched/deadline: Remove superfluous rq clock update in push_dl_task()

> The change to call update_rq_clock() before activate_task()
> commit 840d719604b0 ("sched/deadline: Update rq_clock of later_rq
> when pushing a task") is no longer needed since commit f4904815f97a
> ("sched/deadline: Fix double accounting of rq/running bw in push & pull")
> removed the add_running_bw() before the activate_task().
> 
> So we remove some comments that are no longer needed and update
> rq clock in activate_task().
> 
> Signed-off-by: Hao Jia <jiahao.os@...edance.com>
> ---
>  kernel/sched/deadline.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index fb4255ae0b2c..8eb694ed7ac1 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -2319,13 +2319,7 @@ static int push_dl_task(struct rq *rq)
>  
>  	deactivate_task(rq, next_task, 0);
>  	set_task_cpu(next_task, later_rq->cpu);
> -
> -	/*
> -	 * Update the later_rq clock here, because the clock is used
> -	 * by the cpufreq_update_util() inside __add_running_bw().
> -	 */
> -	update_rq_clock(later_rq);
> -	activate_task(later_rq, next_task, ENQUEUE_NOCLOCK);
> +	activate_task(later_rq, next_task, 0);
>  	ret = 1;
>  
>  	resched_curr(later_rq);

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