linux-kernel - Re: [PATCH] workqueue: flush all pending jobs in destroy

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Message-ID: <aAvhxfGvndybqkJm@slm.duckdns.org>
Date: Fri, 25 Apr 2025 09:25:57 -1000
From: Tejun Heo <tj@...nel.org>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Lai Jiangshan <jiangshanlai@...il.com>,
	Philipp Stanner <phasta@...lbox.org>,
	Danilo Krummrich <dakr@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] workqueue: flush all pending jobs in destroy_workqueue()

Hello,

On Fri, Apr 25, 2025 at 09:33:54AM +0000, Alice Ryhl wrote:
...
> Hmm. I think we would need to add a new field to delayed_work to keep
> track of which list it has been added to.

Can't we use the same cpu that's already recorded in delayed_work->cpu?

> Another option could be to add a boolean that disables the list. After
> all, we never call destroy_workqueue() on system_wq so we don't need the
> list for that workqueue.

It's not just system_wq tho. Any busy workqueue can hit scalability problems
and the result would be usually subtle performance penalties. If we can keep
it cheap enough, I'd prefer the behavior uniform across all workqueues.

Thanks.

-- 
tejun