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From: Juri Lelli <juri.lelli@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Aaron Tomlin <atomlin@atomlin.com>,
	Valentin Schneider <vschneid@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 3/4] kernel/workqueue: Distinguish between general unbound and WQ_SYSFS cpumask changes
Date: Thu, 18 Jan 2024 13:52:57 +0100	[thread overview]
Message-ID: <ZakfKWVdAUZ4wCNf@localhost.localdomain> (raw)
In-Reply-To: <Zagtpw-JQvdpFseh@slm.duckdns.org>

On 17/01/24 09:42, Tejun Heo wrote:
> Hello,
> 
> On Wed, Jan 17, 2024 at 02:32:34PM -0500, Waiman Long wrote:
> > My impression is that changing the workqueue cpumask of ordered unbound
> > workqueue may break the ordering guarantee momentarily. I was planning to
> 
> Ah, you're right. Changing cpumask would require changing the dfl_pwq and
> that can introduce extra concurrency and break ordering and it's exempt from
> unbound_cpumask updates. We likely need to add a mechanism for updating
> ordered wq's so that the new pwq doesn't become until the previous one is
> drained.

Thanks for the additional info! Guess I'll need to think more about this
and possibly coordinate the effort with Waiman.

Best,
Juri


  reply	other threads:[~2024-01-18 12:53 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-16 16:19 [RFC PATCH 0/4] Fix handling of rescuers affinity Juri Lelli
2024-01-16 16:19 ` [RFC PATCH 1/4] tools/workqueue: Add rescuers printing to wq_dump.py Juri Lelli
2024-01-16 16:19 ` [RFC PATCH 2/4] kernel/workqueue: Bind rescuer to unbound cpumask for WQ_UNBOUND Juri Lelli
2024-01-16 18:47   ` Tejun Heo
2024-01-17  6:30     ` Juri Lelli
2024-01-16 16:19 ` [RFC PATCH 3/4] kernel/workqueue: Distinguish between general unbound and WQ_SYSFS cpumask changes Juri Lelli
2024-01-16 18:57   ` Tejun Heo
2024-01-17 13:06     ` Juri Lelli
2024-01-17 17:12       ` Tejun Heo
2024-01-17 19:32         ` Waiman Long
2024-01-17 19:42           ` Tejun Heo
2024-01-18 12:52             ` Juri Lelli [this message]
2024-01-16 16:19 ` [RFC PATCH 4/4] kernel/workqueue: Let rescuers follow unbound wq " Juri Lelli
2024-01-17  3:56   ` Lai Jiangshan
2024-01-17  6:30     ` Juri Lelli

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