From: Vincent Guittot <vincent.guittot@linaro.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Qais Yousef <qais.yousef@arm.com>,
Quentin Perret <qperret@google.com>,
Pavan Kondeti <pkondeti@codeaurora.org>,
Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH 3/8] sched/fair: Tweak misfit-related capacity checks
Date: Fri, 5 Feb 2021 18:17:48 +0100 [thread overview]
Message-ID: <CAKfTPtB_aJE0uDmARvKGe8_oX0Goaada_C5HKy7aaTbFGLxU-A@mail.gmail.com> (raw)
In-Reply-To: <jhjv9b61md0.mognet@arm.com>
On Fri, 5 Feb 2021 at 18:00, Valentin Schneider
<valentin.schneider@arm.com> wrote:
>
> On 05/02/21 15:31, Vincent Guittot wrote:
> > On Thu, 28 Jan 2021 at 19:32, Valentin Schneider
> > <valentin.schneider@arm.com> wrote:
> >>
> >> During load-balance, groups classified as group_misfit_task are filtered
> >> out if they do not pass
> >>
> >> group_smaller_max_cpu_capacity(<candidate group>, <local group>);
> >
> > group_smaller_max_cpu_capacity and group_smaller_max_cpu_capacity are
> > removed in the next patch. Merge this and the next and directly remove
> > them
> >
>
> OK.
>
> >> @@ -8253,7 +8260,7 @@ check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
> >> static inline int check_misfit_status(struct rq *rq, struct sched_domain *sd)
> >> {
> >> return rq->misfit_task_load &&
> >> - (rq->cpu_capacity_orig < rq->rd->max_cpu_capacity ||
> >> + (capacity_greater(rq->rd->max_cpu_capacity, rq->cpu_capacity_orig) ||
> >
> > Why do you add a margin here whereas there was no margin before ?
> >
>
> Comparing capacities without any sort of filter can lead to ping-ponging
> tasks around (capacity values very easily fluctuate by +/- 1, if not more).
max_cpu_capacity reflects the max of the cpu_capacity_orig values
don't aim to change and can be considered as static values.
It would be better to fix this rounding problem (if any) in
topology_get_cpu_scale instead of computing a margin every time it's
used
> I'm guilty of doing two things at once here: replace existing users, and
> convert callsites that should be existing users. I can split the conversion
> in a separate patch.
next prev parent reply other threads:[~2021-02-05 17:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 18:31 [PATCH 0/8] sched/fair: misfit task load-balance tweaks Valentin Schneider
2021-01-28 18:31 ` [PATCH 1/8] sched/fair: Clean up active balance nr_balance_failed trickery Valentin Schneider
2021-02-03 15:14 ` Qais Yousef
2021-02-03 18:42 ` Valentin Schneider
2021-02-04 15:05 ` Qais Yousef
2021-02-05 13:51 ` Vincent Guittot
2021-02-05 14:05 ` Valentin Schneider
2021-02-05 14:34 ` Vincent Guittot
2021-01-28 18:31 ` [PATCH 2/8] sched/fair: Add more sched_asym_cpucapacity static branch checks Valentin Schneider
2021-02-03 15:14 ` Qais Yousef
2021-02-09 8:42 ` Vincent Guittot
2021-01-28 18:31 ` [PATCH 3/8] sched/fair: Tweak misfit-related capacity checks Valentin Schneider
2021-02-03 15:15 ` Qais Yousef
2021-02-03 18:42 ` Valentin Schneider
2021-02-05 14:31 ` Vincent Guittot
2021-02-05 16:59 ` Valentin Schneider
2021-02-05 17:17 ` Vincent Guittot [this message]
2021-02-05 20:07 ` Valentin Schneider
2021-02-08 15:29 ` Vincent Guittot
2021-02-08 17:49 ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 4/8] sched/fair: Use dst_cpu's capacity rather than group {min, max} capacity Valentin Schneider
2021-02-03 15:15 ` Qais Yousef
2021-01-28 18:31 ` [PATCH 5/8] sched/fair: Make check_misfit_status() only compare dynamic capacities Valentin Schneider
2021-02-03 15:15 ` Qais Yousef
2021-02-04 10:49 ` Dietmar Eggemann
2021-02-04 11:34 ` Valentin Schneider
2021-02-04 14:57 ` Dietmar Eggemann
2021-01-28 18:31 ` [PATCH 6/8] sched/fair: Filter out locally-unsolvable misfit imbalances Valentin Schneider
2021-02-03 15:16 ` Qais Yousef
2021-02-03 18:43 ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 7/8] sched/fair: Attempt misfit active balance when migration_type != migrate_misfit Valentin Schneider
2021-02-03 15:16 ` Qais Yousef
2021-02-03 18:43 ` Valentin Schneider
2021-02-04 11:44 ` Dietmar Eggemann
2021-02-04 12:22 ` Valentin Schneider
2021-02-09 8:58 ` Vincent Guittot
2021-02-09 18:19 ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 8/8] sched/fair: Relax task_hot() for misfit tasks Valentin Schneider
2021-02-03 15:17 ` Qais Yousef
2021-02-08 16:21 ` Vincent Guittot
2021-02-08 18:24 ` Valentin Schneider
2021-02-09 8:56 ` Vincent Guittot
2021-02-03 15:14 ` [PATCH 0/8] sched/fair: misfit task load-balance tweaks Qais Yousef
2021-02-03 18:43 ` Valentin Schneider
2021-02-04 12:03 ` Dietmar Eggemann
2021-02-04 12:36 ` Valentin Schneider
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