From: Mel Gorman <mgorman@techsingularity.net>
To: "Li, Aubrey" <aubrey.li@linux.intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Peter Ziljstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Barry Song <song.bao.hua@hisilicon.com>,
Juri Lelli <juri.lelli@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Linux-ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP
Date: Wed, 9 Dec 2020 11:33:00 +0000 [thread overview]
Message-ID: <20201209113300.GN3371@techsingularity.net> (raw)
In-Reply-To: <14963d1e-02ea-c298-d6b4-2db637913ee3@linux.intel.com>
On Wed, Dec 09, 2020 at 07:07:11PM +0800, Li, Aubrey wrote:
> On 2020/12/9 17:05, Mel Gorman wrote:
> > On Wed, Dec 09, 2020 at 01:28:11PM +0800, Li, Aubrey wrote:
> >>>> nr = div_u64(span_avg, avg_cost);
> >>>> else
> >>>> nr = 4;
> >>>> - }
> >>>> -
> >>>> - time = cpu_clock(this);
> >>>>
> >>>> - cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
> >>>> + time = cpu_clock(this);
> >>>> + }
> >>>>
> >>>> for_each_cpu_wrap(cpu, cpus, target) {
> >>>> if (!--nr)
> >>
> >> nr is the key of this throttling mechanism, need to be placed under sched_feat(SIS_PROP) as well.
> >>
> >
> > It isn't necessary as nr in initialised to INT_MAX if !SIS_PROP.
> >If !SIS_PROP, nr need to -1 then tested in the loop, instead of testing directly.
> But with SIS_PROP, need adding a test in the loop.
> Since SIS_PROP is default true, I think it's okay to keep the current way.
>
It's because it's default true and the cost is negligible that I'm leaving
it alone. The branch cost and nr accounting cost is negligible and it
avoids peppering select_idle_cpu() with too many SIS_PROP checks.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2020-12-09 11:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 15:34 [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-08 15:34 ` [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2020-12-08 16:13 ` Vincent Guittot
2020-12-08 15:34 ` [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
2020-12-08 16:03 ` Vincent Guittot
2020-12-08 16:30 ` Mel Gorman
2020-12-09 5:28 ` Li, Aubrey
2020-12-09 9:05 ` Mel Gorman
2020-12-09 11:07 ` Li, Aubrey
2020-12-09 11:33 ` Mel Gorman [this message]
2020-12-10 5:18 ` Li, Aubrey
2020-12-10 9:32 ` Mel Gorman
2020-12-08 15:35 ` [PATCH 3/4] sched/fair: Do not replace recent_used_cpu with the new target Mel Gorman
2020-12-08 16:14 ` Vincent Guittot
2020-12-10 9:40 ` Vincent Guittot
2020-12-08 15:35 ` [PATCH 4/4] sched/fair: Return an idle cpu if one is found after a failed search for an idle core Mel Gorman
2020-12-08 16:15 ` Vincent Guittot
2020-12-09 14:37 ` [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-10 8:00 ` Vincent Guittot
2020-12-10 9:38 ` Vincent Guittot
2020-12-10 11:04 ` Mel Gorman
2020-12-11 9:51 ` Vincent Guittot
2020-12-11 10:23 ` Mel Gorman
2020-12-12 10:02 ` Vincent Guittot
[not found] ` <20201211062542.3082-1-hdanton@sina.com>
2020-12-11 9:02 ` [PATCH 3/4] sched/fair: Do not replace recent_used_cpu with the new target Mel Gorman
[not found] ` <20201211093443.3259-1-hdanton@sina.com>
2020-12-11 9:45 ` Mel Gorman
2021-01-25 8:59 [PATCH v4 0/4] Scan for an idle sibling in a single pass Mel Gorman
2021-01-25 8:59 ` [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
2021-01-27 10:39 ` Vincent Guittot
2021-01-27 13:51 [PATCH v5 0/4] Scan for an idle sibling in a single pass Mel Gorman
2021-01-27 13:52 ` [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
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