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Date:   Tue, 12 Dec 2023 19:06:48 +0000
From:   Aaron Tomlin <atomlin@atomlin.com>
To:     Tejun Heo <tj@kernel.org>
Cc:     Juri Lelli <juri.lelli@redhat.com>, linux-kernel@vger.kernel.org,
        jiangshanlai@gmail.com, peterz@infradead.org
Subject: Re: [RFC PATCH 0/2] workqueue: Introduce PF_WQ_RESCUE_WORKER
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On Tue, Dec 12, 2023 at 07:14:48AM -1000, Tejun Heo wrote:
> Hello, Juri.
> 
> On Tue, Dec 12, 2023 at 10:56:02AM +0100, Juri Lelli wrote:
> > Hummm, OK, but in terms of which CPU the rescuer is possibly woken up,
> > how are we making sure that the wake up is always happening on
> > housekeeping CPUs (assuming unbound workqueues have been restricted to
> > those)?
> > 
> > AFAICS, we have
> > 
> > send_mayday ->
> >   wake_up_process(wq->rescuer->task)
> > 
> > which is not affined to the workqueue cpumask it's called to rescue, so
> > in theory can be woken up anywhere?
> 
> Ah, was only thinking about work item execution. Yeah, it's not following
> the isolation rule there and we probably should affine it as we're waking it
> up.

Hi Tejun,

I am confused.

I thought by design we want a rescuer kthread to execute on any CPU, no?


Kind regards,

-- 
Aaron Tomlin