linux-kernel - Re: [RFC PATCH 3/4] kernel/workqueue: Distinguish between general unbound and WQ

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Date: Wed, 17 Jan 2024 07:12:13 -1000
From: Tejun Heo <tj@...nel.org>
To: Juri Lelli <juri.lelli@...hat.com>
Cc: Lai Jiangshan <jiangshanlai@...il.com>,
	Aaron Tomlin <atomlin@...mlin.com>,
	Valentin Schneider <vschneid@...hat.com>,
	Waiman Long <longman@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 3/4] kernel/workqueue: Distinguish between general
 unbound and WQ_SYSFS cpumask changes

Hello,

On Wed, Jan 17, 2024 at 02:06:08PM +0100, Juri Lelli wrote:
> > This looks rather hacky. Can you elaborate how the current code misbehaves
> > with an example?
> 
> I was trying to address the fact that ordered unbound workqueues didn't
> seem to reflect unbound_cpumask changes, e.g.
> 
> wq_unbound_cpumask=00000003
> 
> edac-poller              ordered,E  0xffffffff 000000ff      kworker/R-edac-            351 0xffffffff 000000ff
> 
> vs. 
> 
> edac-poller              ordered,E  00000003                 kworker/R-edac-            349 00000003
> 
> with the patch applied. But honestly, I'm now also not convinced what
> I'm proposing is correct, so I'll need to think more about it.
> 
> Can you please confirm though that ordered unbound workqueues are not
> "special" for some reason and we would like them to follow
> unbound_cpumask changes as normal ubound workqueues?

They aren't special and should follow the normal unbound workqueue cpumask.

Thanks.

-- 
tejun