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From: Valentin Schneider <valentin.schneider@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, mingo@kernel.org,
	linux-kernel@vger.kernel.org, bigeasy@linutronix.de,
	qais.yousef@arm.com, swood@redhat.com, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com, vincent.donnefort@arm.com, tj@kernel.org,
	ouwen210@hotmail.com
Subject: Re: [PATCH v4 11/19] sched/core: Make migrate disable and CPU hotplug cooperative
Date: Thu, 29 Oct 2020 16:27:09 +0000	[thread overview]
Message-ID: <jhjd011ov4y.mognet@arm.com> (raw)
In-Reply-To: <20201023102347.067278757@infradead.org>


On 23/10/20 11:12, Peter Zijlstra wrote:
> @@ -7006,15 +7024,20 @@ static bool balance_push(struct rq *rq)
>        * Both the cpu-hotplug and stop task are in this case and are
>        * required to complete the hotplug process.
>        */
> -	if (is_per_cpu_kthread(push_task)) {
> +	if (is_per_cpu_kthread(push_task) || is_migration_disabled(push_task)) {

is_migration_disabled(p) implies rq_has_pinned_tasks(task_rq(p)), right?

So having a "simple"

  if (is_migration_disabled(push_task))
        return;

would help simpletons like me trying to read through this.

>               /*
>                * If this is the idle task on the outgoing CPU try to wake
>                * up the hotplug control thread which might wait for the
>                * last task to vanish. The rcuwait_active() check is
>                * accurate here because the waiter is pinned on this CPU
>                * and can't obviously be running in parallel.
> +		 *
> +		 * On RT kernels this also has to check whether there are
> +		 * pinned and scheduled out tasks on the runqueue. They
> +		 * need to leave the migrate disabled section first.
>                */
> -		if (!rq->nr_running && rcuwait_active(&rq->hotplug_wait)) {
> +		if (!rq->nr_running && !rq_has_pinned_tasks(rq) &&
> +		    rcuwait_active(&rq->hotplug_wait)) {
>                       raw_spin_unlock(&rq->lock);
>                       rcuwait_wake_up(&rq->hotplug_wait);
>                       raw_spin_lock(&rq->lock);

  reply	other threads:[~2020-10-29 16:27 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-23 10:11 [PATCH v4 00/19] sched: Migrate disable support Peter Zijlstra
2020-10-23 10:11 ` [PATCH v4 01/19] stop_machine: Add function and caller debug info Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 02/19] sched: Fix balance_callback() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-11-11 20:30     ` Paul Bolle
2020-11-11 20:45       ` Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 03/19] sched/hotplug: Ensure only per-cpu kthreads run during hotplug Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 04/19] sched/core: Wait for tasks being pushed away on hotplug Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2020-10-23 10:12 ` [PATCH v4 05/19] workqueue: Manually break affinity " Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 06/19] sched/hotplug: Consolidate task migration on CPU unplug Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2020-10-23 10:12 ` [PATCH v4 07/19] sched: Fix hotplug vs CPU bandwidth control Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 08/19] sched: Massage set_cpus_allowed() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 09/19] sched: Add migrate_disable() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 10/19] sched: Fix migrate_disable() vs set_cpus_allowed_ptr() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-11-12 16:38   ` [PATCH v4 10/19] " Qian Cai
2020-11-12 17:26     ` Valentin Schneider
2020-11-12 18:01       ` Qian Cai
2020-11-12 19:31         ` Valentin Schneider
2020-11-12 19:41           ` Qian Cai
2020-11-12 20:37           ` Qian Cai
2020-11-12 21:26             ` Valentin Schneider
2020-11-13 10:27           ` Peter Zijlstra
2020-11-12 18:35       ` Qian Cai
2020-11-20 12:34     ` [tip: sched/core] sched/core: Add missing completion for affine_move_task() waiters tip-bot2 for Valentin Schneider
2020-10-23 10:12 ` [PATCH v4 11/19] sched/core: Make migrate disable and CPU hotplug cooperative Peter Zijlstra
2020-10-29 16:27   ` Valentin Schneider [this message]
2020-10-29 17:34     ` Peter Zijlstra
2020-10-29 17:55       ` Valentin Schneider
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2020-11-13 15:06   ` [PATCH v4 11/19] " Qian Cai
2020-11-17 19:28     ` Valentin Schneider
2020-11-18 14:44       ` Qian Cai
2020-11-23 18:13         ` Sebastian Andrzej Siewior
2020-12-02 21:59           ` Qian Cai
2020-12-03 12:31           ` Qian Cai
2020-12-04  0:23       ` Qian Cai
2020-12-04 21:19       ` Qian Cai
2020-12-05 18:37         ` Valentin Schneider
2020-12-06  1:17           ` Qian Cai
2020-12-07 19:27         ` Valentin Schneider
2020-12-08 13:46           ` Qian Cai
2020-12-09 19:16             ` Valentin Schneider
2020-10-23 10:12 ` [PATCH v4 12/19] sched,rt: Use cpumask_any*_distribute() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 13/19] sched,rt: Use the full cpumask for balancing Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 14/19] sched, lockdep: Annotate ->pi_lock recursion Peter Zijlstra
2020-10-29 16:27   ` Valentin Schneider
2020-10-29 17:38     ` Peter Zijlstra
2020-10-29 18:09       ` Valentin Schneider
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 15/19] sched: Fix migrate_disable() vs rt/dl balancing Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-12-26 13:54   ` [PATCH v4 15/19] " Qais Yousef
2021-03-05 14:56     ` Peter Zijlstra
2021-03-05 15:41       ` Valentin Schneider
2021-03-05 17:11         ` Qais Yousef
2021-03-10 14:44         ` Qais Yousef
2021-03-05 16:48       ` Qais Yousef
2020-10-23 10:12 ` [PATCH v4 16/19] sched/proc: Print accurate cpumask vs migrate_disable() Peter Zijlstra
2020-11-11  8:23   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 17/19] sched: Add migrate_disable() tracepoints Peter Zijlstra
2020-10-29 16:27   ` Valentin Schneider
2020-10-29 17:43     ` Peter Zijlstra
2020-10-29 17:56       ` Valentin Schneider
2020-10-29 17:59         ` Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 18/19] sched: Deny self-issued __set_cpus_allowed_ptr() when migrate_disable() Peter Zijlstra
2020-10-23 10:12 ` [PATCH v4 19/19] sched: Comment affine_move_task() Peter Zijlstra
2020-10-29 16:27   ` Valentin Schneider
2020-10-29 17:44     ` Peter Zijlstra
2020-10-29 19:03 ` [PATCH v4 00/19] sched: Migrate disable support Valentin Schneider
2020-11-09 16:39 ` Daniel Bristot de Oliveira

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