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

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Message-ID: <ZMqcGUderg8v5SEz@slm.duckdns.org>
Date:   Wed, 2 Aug 2023 08:10:33 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Aaron Tomlin <atomlin@...mlin.com>
Cc:     peterz@...radead.org, jiangshanlai@...il.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/2] workqueue: Introduce PF_WQ_RESCUE_WORKER

Hello,

On Tue, Aug 01, 2023 at 11:53:01AM +0100, Aaron Tomlin wrote:
> > 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.
> 
> I completely agree. Each kworker has PF_NO_SETAFFINITY applied anyway.
> If I understand correctly, only an unbound kworker can have their CPU
> affinity modified via sysfs. The objective of this series was to easily
> identify a rescuer kworker from user-mode.

But why do you need to identify rescue workers? What are you trying to
achieve?

Thanks.

-- 
tejun