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Message-ID: <20231120114835.GS8262@noisy.programming.kicks-ass.net>
Date: Mon, 20 Nov 2023 12:48:35 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Yiwei Lin <s921975628@...il.com>
Cc: mingo@...hat.com, wuyun.abel@...edance.com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
linux-kernel@...r.kernel.org, s921975627@...il.com
Subject: Re: [PATCH] sched/fair: Update min_vruntime for reweight_entity()
correctly
On Fri, Nov 17, 2023 at 04:01:06PM +0800, Yiwei Lin wrote:
> Since reweight_entity() may have chance to change the weight of
> cfs_rq->curr entity, we should also update_min_vruntime() if
> this is the case
>
> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")
> Signed-off-by: Yiwei Lin <s921975628@...il.com>
Right, but as you wrote in your other patch, min_vruntime isn't all that
critical anymore. I'll go queue this in sched/core, I don't think this
warrants /urgent.
> ---
> kernel/sched/fair.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 07f555857..6fb89f4a3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3815,17 +3815,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
> enqueue_load_avg(cfs_rq, se);
> if (se->on_rq) {
> update_load_add(&cfs_rq->load, se->load.weight);
> - if (!curr) {
> - /*
> - * The entity's vruntime has been adjusted, so let's check
> - * whether the rq-wide min_vruntime needs updated too. Since
> - * the calculations above require stable min_vruntime rather
> - * than up-to-date one, we do the update at the end of the
> - * reweight process.
> - */
> + if (!curr)
> __enqueue_entity(cfs_rq, se);
> - update_min_vruntime(cfs_rq);
> - }
> +
> + /*
> + * The entity's vruntime has been adjusted, so let's check
> + * whether the rq-wide min_vruntime needs updated too. Since
> + * the calculations above require stable min_vruntime rather
> + * than up-to-date one, we do the update at the end of the
> + * reweight process.
> + */
> + update_min_vruntime(cfs_rq);
> }
> }
>
> --
> 2.34.1
>
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