From: Vincent Guittot <vincent.guittot@linaro.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Aubrey Li <aubrey.li@linux.intel.com>,
Barry Song <song.bao.hua@hisilicon.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Ziljstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Linux-ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU
Date: Tue, 8 Dec 2020 15:47:40 +0100 [thread overview]
Message-ID: <CAKfTPtCqGXJa=GfpBZk5To-xVWVtVL8YVMab9PoxFN1=vOwTWQ@mail.gmail.com> (raw)
In-Reply-To: <20201208135358.GJ3371@techsingularity.net>
On Tue, 8 Dec 2020 at 14:54, Mel Gorman <mgorman@techsingularity.net> wrote:
>
> On Tue, Dec 08, 2020 at 02:43:10PM +0100, Vincent Guittot wrote:
> > On Tue, 8 Dec 2020 at 14:36, Mel Gorman <mgorman@techsingularity.net> wrote:
> > >
> > > On Tue, Dec 08, 2020 at 02:24:32PM +0100, Vincent Guittot wrote:
> > > > > > Nitpick:
> > > > > >
> > > > > > Since now avg_cost and avg_idle are only used w/ SIS_PROP, they could go
> > > > > > completely into the SIS_PROP if condition.
> > > > > >
> > > > >
> > > > > Yeah, I can do that. In the initial prototype, that happened in a
> > > > > separate patch that split out SIS_PROP into a helper function and I
> > > > > never merged it back. It's a trivial change.
> > > >
> > > > while doing this, should you also put the update of
> > > > this_sd->avg_scan_cost under the SIS_PROP feature ?
> > > >
> > >
> > > It's outside the scope of the series but why not. This?
> > >
> > > --8<--
> > > sched/fair: Move avg_scan_cost calculations under SIS_PROP
> > >
> > > As noted by Vincent Guittot, avg_scan_costs are calculated for SIS_PROP
> > > even if SIS_PROP is disabled. Move the time calculations under a SIS_PROP
> > > check and while we are at it, exclude the cost of initialising the CPU
> > > mask from the average scan cost.
> > >
> > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> > >
> > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > > index 19ca0265f8aa..0fee53b1aae4 100644
> > > --- a/kernel/sched/fair.c
> > > +++ b/kernel/sched/fair.c
> > > @@ -6176,10 +6176,10 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> > > nr = 4;
> > > }
> > >
> > > - time = cpu_clock(this);
> >
> > I would move it in the if (sched_feat(SIS_PROP)) above.
> >
>
> I considered it but made the choice to exclude the cost of cpumask_and()
> from the avg_scan_cost instead. It's minor but when doing the original
At the cost of a less readable code
> prototype, I didn't think it was appropriate to count the cpumask
> clearing as part of the scan cost as it's not directly related.
hmm... I think it is because the number of loop is directly related to
the allowed cpus
>
> --
> Mel Gorman
> SUSE Labs
next prev parent reply other threads:[~2020-12-08 14:48 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 9:15 [RFC PATCH 0/4] Reduce worst-case scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-07 9:15 ` [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2020-12-07 15:05 ` Vincent Guittot
2020-12-08 10:07 ` Dietmar Eggemann
2020-12-08 10:59 ` Mel Gorman
2020-12-08 13:24 ` Vincent Guittot
2020-12-08 13:36 ` Mel Gorman
2020-12-08 13:43 ` Vincent Guittot
2020-12-08 13:53 ` Mel Gorman
2020-12-08 14:47 ` Vincent Guittot [this message]
2020-12-08 15:12 ` Mel Gorman
2020-12-08 15:19 ` Vincent Guittot
2020-12-07 9:15 ` [PATCH 2/4] sched/fair: Do not replace recent_used_cpu with the new target Mel Gorman
2020-12-08 9:57 ` Dietmar Eggemann
2020-12-08 11:02 ` Mel Gorman
2020-12-07 9:15 ` [PATCH 3/4] sched/fair: Return an idle cpu if one is found after a failed search for an idle core Mel Gorman
2020-12-07 15:06 ` Vincent Guittot
2020-12-07 9:15 ` [PATCH 4/4] sched/fair: Avoid revisiting CPUs multiple times during select_idle_sibling Mel Gorman
2020-12-07 15:04 ` [RFC PATCH 0/4] Reduce worst-case scanning of runqueues in select_idle_sibling Vincent Guittot
2020-12-07 15:42 ` Mel Gorman
2020-12-08 2:06 ` Li, Aubrey
2020-12-08 15:34 [PATCH 0/4] Reduce " 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
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 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
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 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
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