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From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Valentin Schneider <valentin.schneider@arm.com>,
	linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org
Subject: Re: [PATCH v2 8/9] sched/fair: Split select_task_rq_fair want_affine logic
Date: Thu, 19 Mar 2020 11:30:08 +0100	[thread overview]
Message-ID: <c0a1f683-f5c5-cd95-a586-28cc1da9fc3d@arm.com> (raw)
In-Reply-To: <20200311181601.18314-9-valentin.schneider@arm.com>

On 11.03.20 19:16, Valentin Schneider wrote:

[...]

> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index f98dac0c7f82..a6fca6817e92 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6620,26 +6620,33 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
>  	}
>  
>  	rcu_read_lock();
> +
> +	sd = highest_flag_domain(cpu, sd_flag);
> +
> +	/*
> +	 * If !want_affine, we just look for the highest domain where
> +	 * sd_flag is set.
> +	 */
> +	if (!want_affine)
> +		goto scan;
> +
> +	/*
> +	 * Otherwise we look for the lowest domain with SD_WAKE_AFFINE and that
> +	 * spans both 'cpu' and 'prev_cpu'.
> +	 */
>  	for_each_domain(cpu, tmp) {
> -		/*
> -		 * If both 'cpu' and 'prev_cpu' are part of this domain,
> -		 * cpu is a valid SD_WAKE_AFFINE target.
> -		 */
> -		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
> +		if ((tmp->flags & SD_WAKE_AFFINE) &&
>  		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
>  			if (cpu != prev_cpu)
>  				new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
>  
> -			sd = NULL; /* Prefer wake_affine over balance flags */
> +			/* Prefer wake_affine over SD lookup */

I assume that 'balance flags' stands for (wakeup) load balance, i.e.
find_idlest_xxx() path. So why change it?


[...]

  reply	other threads:[~2020-03-19 10:30 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 18:15 [PATCH v2 0/9] sched: Streamline select_task_rq() & select_task_rq_fair() Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 1/9] sched/fair: find_idlest_group(): Remove unused sd_flag parameter Valentin Schneider
2020-03-19  9:05   ` Dietmar Eggemann
2020-03-11 18:15 ` [PATCH v2 2/9] sched/debug: Make sd->flags sysctl read-only Valentin Schneider
2020-03-19  9:07   ` Dietmar Eggemann
2020-03-19 12:04     ` Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 3/9] sched: Remove checks against SD_LOAD_BALANCE Valentin Schneider
2020-03-19 10:28   ` Dietmar Eggemann
2020-03-19 12:05     ` Valentin Schneider
2020-03-23 14:26       ` Dietmar Eggemann
2020-03-23 17:17         ` Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 4/9] sched/topology: Kill SD_LOAD_BALANCE Valentin Schneider
2020-03-19 10:29   ` Dietmar Eggemann
2020-03-19 12:06     ` Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 5/9] sched: Add WF_TTWU, WF_EXEC wakeup flags Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 6/9] sched: Kill select_task_rq()'s sd_flag parameter Valentin Schneider
2020-03-11 18:15 ` [PATCH v2 7/9] sched/fair: Dissociate wakeup decisions from SD flag value Valentin Schneider
2020-03-11 18:16 ` [PATCH v2 8/9] sched/fair: Split select_task_rq_fair want_affine logic Valentin Schneider
2020-03-19 10:30   ` Dietmar Eggemann [this message]
2020-03-19 12:06     ` Valentin Schneider
2020-03-11 18:16 ` [PATCH v2 9/9] sched/topology: Define and use shortcut pointers for wakeup sd_flag scan Valentin Schneider
2020-03-19 10:46   ` Dietmar Eggemann
2020-03-19 12:22     ` Valentin Schneider

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