From: Morten Rasmussen <morten.rasmussen@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, dietmar.eggemann@arm.com, yuyang.du@intel.com,
vincent.guittot@linaro.org, mgalbraith@suse.de,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice
Date: Tue, 7 Jun 2016 15:25:21 +0100 [thread overview]
Message-ID: <20160607142521.GB9187@e105550-lin.cambridge.arm.com> (raw)
In-Reply-To: <20160601195920.GE28447@twins.programming.kicks-ass.net>
On Wed, Jun 01, 2016 at 09:59:20PM +0200, Peter Zijlstra wrote:
> On Mon, May 23, 2016 at 11:58:46AM +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));
> > + }
>
> superfluous brackets, also isn't @this_cpu supposed to be part of the
> sched_group_cpu(group) mask?
I'll kill the brackets.
IIUC, @this_cpu is never part of sched_group_cpus(group).
find_idlest_group() never returns the local group, so if we manage to
get to find_idlest_cpu(), the group would not contain @this_cpu.
next prev parent reply other threads:[~2016-06-07 14:24 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160607142521.GB9187@e105550-lin.cambridge.arm.com \
--to=morten.rasmussen@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgalbraith@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=vincent.guittot@linaro.org \
--cc=yuyang.du@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).