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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/fair: Rearrange select_task_rq_fair() to optimize it
Date: Tue, 24 Apr 2018 16:00:00 +0530	[thread overview]
Message-ID: <20180424103000.74sbxgztf7h7xppb@vireshk-i7> (raw)
In-Reply-To: <434fa179-7c8f-8a01-a07a-4527521a04c7@arm.com>

On 24-04-18, 11:02, Valentin Schneider wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index cacee15..ad09b67 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6613,7 +6613,7 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
>  static int
>  select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags)
>  {
> -	struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
> +	struct sched_domain *tmp, *sd = NULL;
>  	int cpu = smp_processor_id();
>  	int new_cpu = prev_cpu;
>  	int want_affine = 0;
> @@ -6636,8 +6636,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
>  		 */
>  		if (want_affine && (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 */
> -			affine_sd = tmp;
>  			break;
>  		}
>  
> @@ -6657,16 +6659,11 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
>  			sync_entity_load_avg(&p->se);
>  
>  		new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
> -	} else {
> -		if (affine_sd && cpu != prev_cpu)
> -			new_cpu = wake_affine(affine_sd, p, cpu, prev_cpu, sync);
> +	} else if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */
> +		new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
>  
> -		if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */
> -			new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
> -
> -			if (want_affine)
> -				current->recent_used_cpu = cpu;
> -		}
> +		if (want_affine)
> +			current->recent_used_cpu = cpu;
>  	}
>  	rcu_read_unlock();

LGTM.

I will merge it as part of the current patch, but maybe wait for a few
days before sending V2.

-- 
viresh

  reply	other threads:[~2018-04-24 10:30 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-23 10:38 Viresh Kumar
2018-04-24 10:02 ` Valentin Schneider
2018-04-24 10:30   ` Viresh Kumar [this message]
2018-04-24 10:43   ` Peter Zijlstra
2018-04-24 11:19     ` Valentin Schneider
2018-04-24 12:35       ` Peter Zijlstra
2018-04-24 15:46         ` Joel Fernandes
2018-04-24 15:47           ` Joel Fernandes
2018-04-24 22:34             ` Rohit Jain
2018-04-25  2:51               ` Viresh Kumar
2018-04-25 16:48                 ` Rohit Jain
2018-04-25  5:15         ` Viresh Kumar
2018-04-25  8:13           ` Quentin Perret
2018-04-25  9:03             ` Viresh Kumar
2018-04-25  9:39               ` Quentin Perret
2018-04-25 10:13                 ` Viresh Kumar
2018-04-25 10:55                   ` Quentin Perret
2018-04-25  8:12         ` Quentin Perret

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