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 8/8] sched/fair: Relax task_hot() for misfit tasks
Date: Mon, 8 Feb 2021 17:21:50 +0100 [thread overview]
Message-ID: <CAKfTPtDBPREA2oBXZ0=-396Dxh5WMYgNTF+=6d_+K-WVjq3Sag@mail.gmail.com> (raw)
In-Reply-To: <20210128183141.28097-9-valentin.schneider@arm.com>
On Thu, 28 Jan 2021 at 19:32, Valentin Schneider
<valentin.schneider@arm.com> wrote:
>
> Misfit tasks can and will be preempted by the stopper to migrate them over
> to a higher-capacity CPU. However, when runnable but not current misfit
> tasks are scanned by the load balancer (i.e. detach_tasks()), the
> task_hot() ratelimiting logic may prevent us from enqueuing said task onto
> a higher-capacity CPU.
>
> Align detach_tasks() with the active-balance logic and let it pick a
> cache-hot misfit task when the destination CPU can provide a capacity
> uplift.
>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> ---
> kernel/sched/fair.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index cba9f97d9beb..c2351b87824f 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7484,6 +7484,17 @@ static int task_hot(struct task_struct *p, struct lb_env *env)
> if (env->sd->flags & SD_SHARE_CPUCAPACITY)
> return 0;
>
> + /*
> + * On a (sane) asymmetric CPU capacity system, the increase in compute
> + * capacity should offset any potential performance hit caused by a
> + * migration.
> + */
> + if (sd_has_asym_cpucapacity(env->sd) &&
> + env->idle != CPU_NOT_IDLE &&
> + !task_fits_capacity(p, capacity_of(env->src_cpu)) &&
> + cpu_capacity_greater(env->dst_cpu, env->src_cpu))
Why not using env->migration_type to directly detect that it's a
misfit task active migration ?
> + return 0;
> +
> /*
> * Buddy candidates are cache hot:
> */
> --
> 2.27.0
>
next prev parent reply other threads:[~2021-02-08 18:36 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
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 [this message]
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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