From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Morten Rasmussen <morten.rasmussen@arm.com>,
peterz@infradead.org, mingo@redhat.com
Cc: dietmar.eggemann@arm.com, yuyang.du@intel.com,
vincent.guittot@linaro.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice
Date: Tue, 24 May 2016 08:29:05 +0200 [thread overview]
Message-ID: <1464071345.3743.22.camel@gmail.com> (raw)
In-Reply-To: <1464001138-25063-5-git-send-email-morten.rasmussen@arm.com>
On Mon, 2016-05-23 at 11:58 +0100, Morten Rasmussen wrote:
> In the current find_idlest_group()/find_idlest_cpu() search we end up
> calling find_idlest_cpu() in a sched_group containing only one cpu in
> the end. Checking idle-states becomes pointless when there is no
> alternative, so bail out instead.
>
> cc: Ingo Molnar <mingo@redhat.com>
> cc: Peter Zijlstra <peterz@infradead.org>
>
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
> kernel/sched/fair.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 0fe3020..564215d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5155,6 +5155,11 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
> > > int shallowest_idle_cpu = -1;
> > > int i;
>
> +> > /* Check if we have any choice */
> +> > if (group->group_weight == 1) {
> +> > > return cpumask_first(sched_group_cpus(group));
> +> > }
> +
Hm, if task isn't allowed there, too bad?
> /* Traverse only the allowed CPUs */
> > > for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
> > > > if (idle_cpu(i)) {
next prev parent reply other threads:[~2016-05-24 6:29 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-23 10:58 [PATCH 00/16] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-05-23 10:58 ` [PATCH 01/16] sched: Fix power to capacity renaming in comment Morten Rasmussen
2016-05-23 10:58 ` [PATCH 02/16] sched/fair: Consistent use of prev_cpu in wakeup path Morten Rasmussen
2016-06-01 19:49 ` Peter Zijlstra
2016-05-23 10:58 ` [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Morten Rasmussen
2016-05-23 11:12 ` Mike Galbraith
2016-05-23 12:00 ` Morten Rasmussen
2016-05-23 13:00 ` Mike Galbraith
2016-05-23 14:10 ` Morten Rasmussen
2016-05-23 15:42 ` Mike Galbraith
2016-05-23 23:17 ` Yuyang Du
2016-05-23 23:04 ` Yuyang Du
2016-06-01 19:57 ` Peter Zijlstra
2016-06-02 8:05 ` Peter Zijlstra
2016-06-07 12:08 ` Morten Rasmussen
2016-05-23 10:58 ` [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice Morten Rasmussen
2016-05-24 6:29 ` Mike Galbraith [this message]
2016-05-24 8:05 ` Morten Rasmussen
2016-05-24 8:12 ` Mike Galbraith
2016-06-01 19:59 ` Peter Zijlstra
2016-06-07 14:25 ` Morten Rasmussen
2016-05-23 10:58 ` [PATCH 05/16] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Morten Rasmussen
2016-05-23 10:58 ` [PATCH 06/16] sched: Disable WAKE_AFFINE for asymmetric configurations Morten Rasmussen
2016-05-24 9:10 ` Vincent Guittot
2016-05-24 10:29 ` Morten Rasmussen
2016-05-24 12:12 ` Vincent Guittot
2016-05-24 13:16 ` Morten Rasmussen
2016-05-24 13:27 ` Vincent Guittot
2016-05-24 13:36 ` Morten Rasmussen
2016-05-24 13:52 ` Vincent Guittot
2016-05-24 15:02 ` Morten Rasmussen
2016-05-24 15:53 ` Vincent Guittot
2016-05-25 9:12 ` Morten Rasmussen
2016-05-26 6:45 ` Vincent Guittot
2016-06-07 16:50 ` Morten Rasmussen
2016-05-23 10:58 ` [PATCH 07/16] sched: Make SD_BALANCE_WAKE a topology flag Morten Rasmussen
2016-05-24 23:52 ` Yuyang Du
2016-05-25 9:27 ` Morten Rasmussen
2016-06-01 20:18 ` Peter Zijlstra
2016-06-08 8:45 ` Morten Rasmussen
2016-05-23 10:58 ` [PATCH 08/16] sched: Store maximum per-cpu capacity in root domain Morten Rasmussen
2016-05-23 10:58 ` [PATCH 09/16] sched/fair: Let asymmetric cpu configurations balance at wake-up Morten Rasmussen
2016-05-24 0:04 ` Yuyang Du
2016-05-24 8:10 ` Morten Rasmussen
2016-05-24 7:03 ` Mike Galbraith
2016-05-24 7:15 ` Mike Galbraith
2016-05-25 6:57 ` Wanpeng Li
2016-05-25 9:49 ` Morten Rasmussen
2016-05-25 10:29 ` Wanpeng Li
2016-05-25 10:54 ` Morten Rasmussen
2016-05-25 11:18 ` Wanpeng Li
2016-06-02 14:21 ` Peter Zijlstra
2016-06-08 11:29 ` Morten Rasmussen
2016-06-08 14:36 ` Peter Zijlstra
2016-05-23 10:58 ` [PATCH 10/16] sched/fair: Compute task/cpu utilization at wake-up more correctly Morten Rasmussen
2016-05-23 10:58 ` [PATCH 11/16] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-05-23 10:58 ` [PATCH 12/16] sched: Add per-cpu max capacity to sched_group_capacity Morten Rasmussen
2016-05-23 10:58 ` [PATCH 13/16] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
2016-05-23 10:58 ` [PATCH 14/16] arm: Set SD_ASYM_CPUCAPACITY for big.LITTLE platforms Morten Rasmussen
2016-05-23 10:58 ` [PATCH 15/16] arm: Set SD_BALANCE_WAKE flag for asymmetric capacity systems Morten Rasmussen
2016-05-23 10:58 ` [PATCH 16/16] arm: Update arch_scale_cpu_capacity() to reflect change to define Morten Rasmussen
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