linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Valentin Schneider <vschneid@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Juri Lelli <juri.lelli@redhat.com>, Phil Auld <pauld@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [RFC PATCH] workqueue: Unbind workers before sending them to exit()
Date: Wed, 20 Jul 2022 08:03:56 -1000	[thread overview]
Message-ID: <YthDjPq3CtWc+o0/@slm.duckdns.org> (raw)
In-Reply-To: <20220719165743.3409313-1-vschneid@redhat.com>

On Tue, Jul 19, 2022 at 05:57:43PM +0100, Valentin Schneider wrote:
> 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 (sleeping workfn's exacerbate this) during
> initial setup can cause extra per-CPU kworkers to be spawned. Then, a
> 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).
> 
> Affine kworkers to the wq_unbound_cpumask (which doesn't contain isolated
> CPUs, cf. HK_TYPE_WQ) before waking them up after marking them with
> WORKER_DIE.
> 
> This follows the logic of CPU hot-unplug, which has been packaged into
> helpers for the occasion.

Idea-wise, seems fine to me, but we have some other issues around twiddling
cpu affinities right now, so let's wait a bit till Lai chimes in.

Thanks.

-- 
tejun

  parent reply	other threads:[~2022-07-20 18:04 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-19 16:57 [RFC PATCH] workqueue: Unbind workers before sending them to exit() Valentin Schneider
2022-07-20 17:54 ` Marcelo Tosatti
2022-07-20 18:03 ` Tejun Heo [this message]
2022-07-21  3:35   ` Lai Jiangshan
2022-07-21 13:53     ` Valentin Schneider
2022-07-23  5:16       ` Tejun Heo
2022-07-25 10:21         ` Valentin Schneider
2022-07-26 17:30           ` Tejun Heo
2022-07-26 20:36             ` Valentin Schneider
2022-07-26 22:59               ` Tejun Heo
2022-07-27  5:38               ` Lai Jiangshan
2022-07-27  6:30                 ` Lai Jiangshan
2022-07-27  8:55                   ` Lai Jiangshan
2022-07-27  9:22                     ` Valentin Schneider

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=YthDjPq3CtWc+o0/@slm.duckdns.org \
    --to=tj@kernel.org \
    --cc=frederic@kernel.org \
    --cc=jiangshanlai@gmail.com \
    --cc=juri.lelli@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mtosatti@redhat.com \
    --cc=pauld@redhat.com \
    --cc=peterz@infradead.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;
as well as URLs for NNTP newsgroup(s).