Re: [RFC PATCH 3/4] kernel/workqueue: Distinguish between general unbound and WQ_SYSFS cpumask changes

[Tejun Heo]

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.

-- 
tejun