From: Valentin Schneider <valentin.schneider@arm.com>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
Qian Cai <cai@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
Vincent Donnefort <vincent.donnefort@arm.com>,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 10/10] workqueue: Fix affinity of kworkers when attaching into pool
Date: Tue, 15 Dec 2020 15:03:20 +0000 [thread overview]
Message-ID: <jhjczzbt8lj.mognet@arm.com> (raw)
In-Reply-To: <20201214155457.3430-11-jiangshanlai@gmail.com>
On 14/12/20 15:54, Lai Jiangshan wrote:
> @@ -1848,11 +1848,11 @@ static void worker_attach_to_pool(struct worker *worker,
> {
> mutex_lock(&wq_pool_attach_mutex);
>
> - /*
> - * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
> - * online CPUs. It'll be re-applied when any of the CPUs come up.
> - */
> - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
> + /* Is there any cpu in pool->attrs->cpumask online? */
> + if (cpumask_any_and(pool->attrs->cpumask, wq_online_cpumask) < nr_cpu_ids)
if (cpumask_intersects(pool->attrs->cpumask, wq_online_cpumask))
> + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0);
> + else
> + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
So for that late-spawned per-CPU kworker case: the outgoing CPU should have
already been cleared from wq_online_cpumask, so it gets its affinity reset
to the possible mask and the subsequent wakeup will ensure it's put on an
active CPU.
Seems alright to me.
>
> /*
> * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains
next prev parent reply other threads:[~2020-12-15 15:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 15:54 [PATCH 00/10] workqueue: break affinity initiatively Lai Jiangshan
2020-12-14 15:54 ` [PATCH 01/10] workqueue: restore unbound_workers' cpumask correctly Lai Jiangshan
2020-12-14 15:54 ` [PATCH 02/10] workqueue: use cpu_possible_mask instead of cpu_active_mask to break affinity Lai Jiangshan
2020-12-14 17:25 ` Peter Zijlstra
2020-12-15 8:33 ` Lai Jiangshan
2020-12-15 8:40 ` Peter Zijlstra
2020-12-16 14:32 ` Tejun Heo
2020-12-14 15:54 ` [PATCH 03/10] workqueue: Manually break affinity on pool detachment Lai Jiangshan
2020-12-14 15:54 ` [PATCH 04/10] workqueue: don't set the worker's cpumask when kthread_bind_mask() Lai Jiangshan
2020-12-16 14:39 ` Tejun Heo
2020-12-14 15:54 ` [PATCH 05/10] workqueue: introduce wq_online_cpumask Lai Jiangshan
2020-12-14 15:54 ` [PATCH 06/10] workqueue: use wq_online_cpumask in restore_unbound_workers_cpumask() Lai Jiangshan
2020-12-14 15:54 ` [PATCH 07/10] workqueue: Manually break affinity on hotplug for unbound pool Lai Jiangshan
2020-12-16 14:50 ` Tejun Heo
2020-12-14 15:54 ` [PATCH 08/10] workqueue: reorganize workqueue_online_cpu() Lai Jiangshan
2020-12-14 15:54 ` [PATCH 09/10] workqueue: reorganize workqueue_offline_cpu() unbind_workers() Lai Jiangshan
2020-12-14 15:54 ` [PATCH 10/10] workqueue: Fix affinity of kworkers when attaching into pool Lai Jiangshan
2020-12-15 15:03 ` Valentin Schneider [this message]
2020-12-14 17:36 ` [PATCH 00/10] workqueue: break affinity initiatively Peter Zijlstra
2020-12-15 5:44 ` Lai Jiangshan
2020-12-15 7:50 ` Peter Zijlstra
2020-12-15 8:14 ` Lai Jiangshan
2020-12-15 8:49 ` Peter Zijlstra
2020-12-15 9:46 ` Lai Jiangshan
2020-12-16 14:30 ` Tejun Heo
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