From: Peter Zijlstra <peterz@infradead.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
Hillf Danton <hdanton@sina.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Qian Cai <cai@redhat.com>,
Vincent Donnefort <vincent.donnefort@arm.com>,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 00/10] workqueue: break affinity initiatively
Date: Mon, 14 Dec 2020 18:36:46 +0100 [thread overview]
Message-ID: <X9eirnnrD/+VqqEo@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201214155457.3430-1-jiangshanlai@gmail.com>
On Mon, Dec 14, 2020 at 11:54:47PM +0800, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
>
> 06249738a41a ("workqueue: Manually break affinity on hotplug")
> said that scheduler will not force break affinity for us.
>
> But workqueue highly depends on the old behavior. Many parts of the codes
> relies on it, 06249738a41a ("workqueue: Manually break affinity on hotplug")
> is not enough to change it, and the commit has flaws in itself too.
>
> We need to thoroughly update the way workqueue handles affinity
> in cpu hot[un]plug, what is this patchset intends to do and
> replace the Valentin Schneider's patch [1].
So the actual problem is with per-cpu kthreads, the new assumption is
that hot-un-plug will make all per-cpu kthreads for the dying CPU go
away.
Workqueues violated that. I fixed the obvious site, and Valentin's patch
avoids workqueues from quickly creating new ones while we're not
looking.
What other problems did you find?
next prev parent reply other threads:[~2020-12-14 18:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 15:54 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
2020-12-14 17:36 ` Peter Zijlstra [this message]
2020-12-15 5:44 ` [PATCH 00/10] workqueue: break affinity initiatively 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
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=X9eirnnrD/+VqqEo@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=cai@redhat.com \
--cc=hdanton@sina.com \
--cc=jiangshanlai@gmail.com \
--cc=laijs@linux.alibaba.com \
--cc=linux-kernel@vger.kernel.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
all inboxes | Powered by JetHome®