linux-kernel - Re: [RFC PATCH 0/2] workqueue: Introduce PF_WQ_RESCUE

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Message-ID: <ZMhFUbL42Ycyc2tI@slm.duckdns.org>
Date:   Mon, 31 Jul 2023 13:35:45 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Aaron Tomlin <atomlin@...mlin.com>
Cc:     linux-kernel@...r.kernel.org, jiangshanlai@...il.com,
        peterz@...radead.org
Subject: Re: [RFC PATCH 0/2] workqueue: Introduce PF_WQ_RESCUE_WORKER

Hello,

On Sat, Jul 29, 2023 at 02:53:32PM +0100, Aaron Tomlin wrote:
> It can be useful to identify a rescue kworker since their CPU affinity
> cannot be modified and their initial CPU assignment can be safely ignored.

You really shouldn't be setting affinities on kworkers manually. There's no
way of knowing which kworker is going to execute which workqueue. Please use
the attributes API and sysfs interface to modify per-workqueue worker
attributes. If that's not sufficient and you need finer grained control, the
right thing to do is using kthread_worker which gives you a dedicated
kthread that you can manipulate as appropriate.

Thanks.

-- 
tejun