From: Hillf Danton <hdanton@sina.com>
To: Valentin Schneider <vschneid@redhat.com>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>,
linux-mm@kvack.org, Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH v7 4/4] workqueue: Unbind kworkers before sending them to exit()
Date: Wed, 11 Jan 2023 11:33:51 +0800 [thread overview]
Message-ID: <20230111033351.385-1-hdanton@sina.com> (raw)
In-Reply-To: <20230109133316.4026472-5-vschneid@redhat.com>
On 9 Jan 2023 13:33:16 +0000 Valentin Schneider <vschneid@redhat.com>
> It has been reported that isolated CPUs can suffer from interference due to
> per-CPU kworkers waking up just to die.
>
> A surge of workqueue activity during initial setup of a latency-sensitive
> application (refresh_vm_stats() being one of the culprits) can cause extra
> per-CPU kworkers to be spawned. Then, said latency-sensitive task can be
> running merrily on an isolated CPU only to be interrupted sometime later by
> a kworker marked for death (cf. IDLE_WORKER_TIMEOUT, 5 minutes after last
> kworker activity).
Given no scheduling in userspace, how is the latency-sensitive task interrupted
by woken kworker?
If it is due to wakeup preempt then disabling it on isolated CPU for user mode
makes more sense, but that should add change to scheduler instead.
parent reply other threads:[~2023-01-11 3:34 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20230109133316.4026472-5-vschneid@redhat.com>]
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=20230111033351.385-1-hdanton@sina.com \
--to=hdanton@sina.com \
--cc=frederic@kernel.org \
--cc=jiangshanlai@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mtosatti@redhat.com \
--cc=peterz@infradead.org \
--cc=tj@kernel.org \
--cc=vschneid@redhat.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