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>,
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 V2 03/10] workqueue: Manually break affinity on pool detachment
Date: Sat, 19 Dec 2020 01:09:12 +0800 [thread overview]
Message-ID: <20201218170919.2950-4-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20201218170919.2950-1-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 fa71520822f0..4d7575311198 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:[~2020-12-18 16:09 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 17:09 [PATCH -tip V2 00/10] workqueue: break affinity initiatively Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 01/10] workqueue: restore unbound_workers' cpumask correctly Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 02/10] workqueue: use cpu_possible_mask instead of cpu_active_mask to break affinity Lai Jiangshan
2020-12-18 17:09 ` Lai Jiangshan [this message]
2020-12-18 17:09 ` [PATCH -tip V2 04/10] workqueue: don't set the worker's cpumask when kthread_bind_mask() Lai Jiangshan
2020-12-24 6:33 ` [workqueue] 6094661b16: WARNING:at_kernel/sched/core.c:#__set_cpus_allowed_ptr kernel test robot
2020-12-18 17:09 ` [PATCH -tip V2 05/10] workqueue: introduce wq_online_cpumask Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 06/10] workqueue: use wq_online_cpumask in restore_unbound_workers_cpumask() Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 07/10] workqueue: Manually break affinity on hotplug for unbound pool Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 08/10] workqueue: reorganize workqueue_online_cpu() Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 09/10] workqueue: reorganize workqueue_offline_cpu() unbind_workers() Lai Jiangshan
2020-12-18 17:09 ` [PATCH -tip V2 10/10] workqueue: Fix affinity of kworkers when attaching into pool Lai Jiangshan
2020-12-18 17:59 ` Valentin Schneider
2020-12-19 1:11 ` Lai Jiangshan
2020-12-22 21:39 ` [PATCH -tip V2 00/10] workqueue: break affinity initiatively Dexuan-Linux Cui
2020-12-23 11:32 ` Lai Jiangshan
2020-12-23 15:01 ` Lai Jiangshan
2020-12-23 20:27 ` Dexuan Cui
2020-12-23 20:39 ` Dexuan Cui
2020-12-23 19:49 ` Paul E. McKenney
[not found] ` <20201226103421.6616-1-hdanton@sina.com>
2020-12-26 14:52 ` Paul E. McKenney
2020-12-27 14:08 ` Lai Jiangshan
2020-12-27 16:02 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201218170919.2950-4-jiangshanlai@gmail.com \
--to=jiangshanlai@gmail.com \
--cc=bristot@redhat.com \
--cc=cai@redhat.com \
--cc=laijs@linux.alibaba.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=tj@kernel.org \
--cc=valentin.schneider@arm.com \
--cc=vincent.donnefort@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).