linux-kernel - Re: [PATCH] sched/fair: merge same code in enqueue_task

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Message-ID: <CAKfTPtCMOPVhjpLW3Y3fb4=rfYnAKzYeDmdMCRHjPzZdXYjVxg@mail.gmail.com>
Date:   Mon, 11 Dec 2023 16:23:52 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     WangJinchao <wangjinchao@...sion.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org, stone.xulei@...sion.com
Subject: Re: [PATCH] sched/fair: merge same code in enqueue_task_fair

On Sun, 10 Dec 2023 at 10:22, WangJinchao <wangjinchao@...sion.com> wrote:
>
> 1. The code below is duplicated in two for loops and need to be
>    consolidated
> 2. Fix the bug where a se's on_rq is true but its parent is not

Could you clarify which bug you want to fix ?




>
> ```c
>                 cfs_rq->h_nr_running++;
>                 cfs_rq->idle_h_nr_running += idle_h_nr_running;
>
>                 if (cfs_rq_is_idle(cfs_rq))
>                         idle_h_nr_running = 1;
>
>                 /* end evaluation on encountering a throttled cfs_rq */
>                 if (cfs_rq_throttled(cfs_rq))
>                         goto enqueue_throttle;
> ```
>
> Signed-off-by: WangJinchao <wangjinchao@...sion.com>
> ---
>  kernel/sched/fair.c | 31 ++++++++-----------------------
>  1 file changed, 8 insertions(+), 23 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index d7a3c63a2171..e1373bfd4f2e 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6681,30 +6681,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>                 cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
>
>         for_each_sched_entity(se) {
> -               if (se->on_rq)
> -                       break;
>                 cfs_rq = cfs_rq_of(se);
> -               enqueue_entity(cfs_rq, se, flags);
> -
> -               cfs_rq->h_nr_running++;
> -               cfs_rq->idle_h_nr_running += idle_h_nr_running;
> -
> -               if (cfs_rq_is_idle(cfs_rq))
> -                       idle_h_nr_running = 1;
> -
> -               /* end evaluation on encountering a throttled cfs_rq */
> -               if (cfs_rq_throttled(cfs_rq))
> -                       goto enqueue_throttle;
> -
> -               flags = ENQUEUE_WAKEUP;
> -       }
> -
> -       for_each_sched_entity(se) {
> -               cfs_rq = cfs_rq_of(se);
> -
> -               update_load_avg(cfs_rq, se, UPDATE_TG);
> -               se_update_runnable(se);
> -               update_cfs_group(se);
> +               if (se->on_rq) {
> +                       update_load_avg(cfs_rq, se, UPDATE_TG);
> +                       se_update_runnable(se);
> +                       update_cfs_group(se);
> +               } else {
> +                       enqueue_entity(cfs_rq, se, flags);
> +                       flags = ENQUEUE_WAKEUP;
> +               }
>
>                 cfs_rq->h_nr_running++;
>                 cfs_rq->idle_h_nr_running += idle_h_nr_running;
> --
> 2.40.0
>