From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Valentin Schneider <valentin.schneider@arm.com>,
Peter Zijlstra <peterz@infradead.org>, Qian Cai <cai@redhat.com>,
Vincent Donnefort <vincent.donnefort@arm.com>,
Dexuan Cui <decui@microsoft.com>,
Lai Jiangshan <laijs@linux.alibaba.com>,
Tejun Heo <tj@kernel.org>, Lai Jiangshan <jiangshanlai@gmail.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: [PATCH -tip V3 2/8] workqueue: Manually break affinity on pool detachment
Date: Sat, 26 Dec 2020 10:51:10 +0800 [thread overview]
Message-ID: <20201226025117.2770-3-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20201226025117.2770-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <laijs@linux.alibaba.com>
The pool->attrs->cpumask might be a single CPU and it may go
down after detachment, and the scheduler won't force to break
affinity for us since it is a per-cpu-ktrhead. So we have to
do it on our own and unbind this worker which can't be unbound
by workqueue_offline_cpu() since it doesn't belong to any pool
after detachment. Do it unconditionally for there is no harm
to break affinity for non-per-cpu-ktrhead and we don't need to
rely on the scheduler's policy on when to break affinity.
Fixes: 06249738a41a ("workqueue: Manually break affinity on hotplug")
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
kernel/workqueue.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f2b8f3d458d1..ccbceacaea1b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1885,6 +1885,19 @@ static void worker_detach_from_pool(struct worker *worker)
if (list_empty(&pool->workers))
detach_completion = pool->detach_completion;
+
+ /*
+ * The pool->attrs->cpumask might be a single CPU and it may go
+ * down after detachment, and the scheduler won't force to break
+ * affinity for us since it is a per-cpu-ktrhead. So we have to
+ * do it on our own and unbind this worker which can't be unbound
+ * by workqueue_offline_cpu() since it doesn't belong to any pool
+ * after detachment. Do it unconditionally for there is no harm
+ * to break affinity for non-per-cpu-ktrhead and we don't need to
+ * rely on the scheduler's policy on when to break affinity.
+ */
+ set_cpus_allowed_ptr(worker->task, cpu_possible_mask);
+
mutex_unlock(&wq_pool_attach_mutex);
/* clear leftover flags without pool->lock after it is detached */
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2020-12-26 1:51 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-26 2:51 [PATCH -tip V3 0/8] workqueue: break affinity initiatively Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 1/8] workqueue: use cpu_possible_mask instead of cpu_active_mask to break affinity Lai Jiangshan
2020-12-26 2:51 ` Lai Jiangshan [this message]
2020-12-26 2:51 ` [PATCH -tip V3 3/8] workqueue: introduce wq_online_cpumask Lai Jiangshan
2021-01-04 13:56 ` Peter Zijlstra
2021-01-05 2:41 ` Lai Jiangshan
2021-01-05 2:53 ` Lai Jiangshan
2021-01-05 8:23 ` Lai Jiangshan
2021-01-05 13:17 ` Peter Zijlstra
2021-01-05 14:37 ` Lai Jiangshan
2021-01-05 14:40 ` Lai Jiangshan
2021-01-05 16:24 ` Peter Zijlstra
2020-12-26 2:51 ` [PATCH -tip V3 4/8] workqueue: use wq_online_cpumask in restore_unbound_workers_cpumask() Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 5/8] workqueue: Manually break affinity on hotplug for unbound pool Lai Jiangshan
[not found] ` <20201226101631.5448-1-hdanton@sina.com>
2020-12-27 14:04 ` Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 6/8] workqueue: reorganize workqueue_online_cpu() Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 7/8] workqueue: reorganize workqueue_offline_cpu() unbind_workers() Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 8/8] workqueue: Fix affinity of kworkers when attaching into pool Lai Jiangshan
[not found] ` <20201229100639.2086-1-hdanton@sina.com>
2020-12-29 10:13 ` Lai Jiangshan
2021-01-08 11:46 ` [PATCH -tip V3 0/8] workqueue: break affinity initiatively Peter Zijlstra
2021-01-11 10:07 ` Thomas Gleixner
2021-01-11 11:01 ` Peter Zijlstra
2021-01-11 15:00 ` Paul E. McKenney
2021-01-11 17:16 ` Peter Zijlstra
2021-01-11 18:09 ` Paul E. McKenney
2021-01-11 21:50 ` Paul E. McKenney
2021-01-12 17:14 ` Paul E. McKenney
2021-01-12 23:53 ` Paul E. McKenney
2021-01-15 9:11 ` Peter Zijlstra
2021-01-15 13:04 ` Peter Zijlstra
2021-01-16 6:00 ` Lai Jiangshan
2021-01-11 19:21 ` Valentin Schneider
2021-01-11 20:23 ` Peter Zijlstra
2021-01-11 22:47 ` Valentin Schneider
2021-01-12 4:33 ` Lai Jiangshan
2021-01-12 14:53 ` Peter Zijlstra
2021-01-12 15:38 ` Lai Jiangshan
2021-01-13 11:10 ` Peter Zijlstra
2021-01-13 12:00 ` Lai Jiangshan
2021-01-13 12:57 ` Lai Jiangshan
2021-01-12 17:52 ` Valentin Schneider
2021-01-12 14:57 ` Jens Axboe
2021-01-12 15:51 ` Peter Zijlstra
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