linux-kernel - Re: [PATCH] sched/fair: remove the DOUBLE

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Message-ID: <Zvv6BdRIlg3QUzoy@linux.ibm.com>
Date: Tue, 1 Oct 2024 19:02:53 +0530
From: Vishal Chourasia <vishalc@...ux.ibm.com>
To: Huang Shijie <shijie@...amperecomputing.com>
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        patches@...erecomputing.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, vschneid@...hat.com, linux-kernel@...r.kernel.org,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH] sched/fair: remove the DOUBLE_TICK feature

On Tue, Oct 01, 2024 at 02:54:51PM +0800, Huang Shijie wrote:
> The patch "5e963f2bd46 sched/fair: Commit to EEVDF"
> removed the code following the DOUBLE_TICK:
> 	-
> 	-       if (!sched_feat(EEVDF) && cfs_rq->nr_running > 1)
> 	-               check_preempt_tick(cfs_rq, curr);
> 
> The DOUBLE_TICK feature becomes dead code now, so remove it.
> 
> Reviewed-by: Christoph Lameter (Ampere) <cl@...ux.com>
> Signed-off-by: Huang Shijie <shijie@...amperecomputing.com>

Reviewed-by: Vishal Chourasia <vishalc@...ux.ibm.com>

[1] https://lore.kernel.org/all/20240308052304.1835792-2-vishalc@linux.ibm.com
> ---
>  kernel/sched/fair.c     | 6 ------
>  kernel/sched/features.h | 1 -
>  2 files changed, 7 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 19afc2253c4d..1812c9cc079d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5680,12 +5680,6 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
>  		resched_curr(rq_of(cfs_rq));
>  		return;
>  	}
> -	/*
> -	 * don't let the period tick interfere with the hrtick preemption
> -	 */
> -	if (!sched_feat(DOUBLE_TICK) &&
> -			hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
> -		return;
>  #endif
>  }
>  
> diff --git a/kernel/sched/features.h b/kernel/sched/features.h
> index 0ae351974e49..a3d331dd2d8f 100644
> --- a/kernel/sched/features.h
> +++ b/kernel/sched/features.h
> @@ -56,7 +56,6 @@ SCHED_FEAT(WAKEUP_PREEMPTION, true)
>  
>  SCHED_FEAT(HRTICK, false)
>  SCHED_FEAT(HRTICK_DL, false)
> -SCHED_FEAT(DOUBLE_TICK, false)
>  
>  /*
>   * Decrement CPU capacity based on time not spent running tasks
> -- 
> 2.40.1
>