linux-kernel - Re: [PATCH 1/3] drm/i915: replace use of system_unbound_wq with system_dfl

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Message-ID: <zduzgow2hyvxfzmrhqansber4eeg63av6i533oihvx4ubxdqaz@wu64gw66b4jt>
Date: Mon, 3 Nov 2025 10:19:07 +0000
From: Krzysztof Karas <krzysztof.karas@...el.com>
To: Marco Crivellari <marco.crivellari@...e.com>
CC: <linux-kernel@...r.kernel.org>, <intel-gfx@...ts.freedesktop.org>,
	<dri-devel@...ts.freedesktop.org>, Tejun Heo <tj@...nel.org>, Lai Jiangshan
	<jiangshanlai@...il.com>, Frederic Weisbecker <frederic@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Michal Hocko
	<mhocko@...e.com>, Jani Nikula <jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Subject: Re: [PATCH 1/3] drm/i915: replace use of system_unbound_wq with
 system_dfl_wq

Hi Marco,

> Currently if a user enqueue a work item using schedule_delayed_work() the
> used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
> WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
> schedule_work() that is using system_wq and queue_work(), that makes use
> again of WORK_CPU_UNBOUND.
> 
> This lack of consistency cannot be addressed without refactoring the API.
> 
> system_unbound_wq should be the default workqueue so as not to enforce
> locality constraints for random work whenever it's not required.
This commit message is very similar to your previous change:
128ea9f6ccfb6960293ae4212f4f97165e42222d - did you do that
intentionally or is this a copy-paste mistake? This is also
prevalent in other two patches, so I am curious.

> 
> Adding system_dfl_wq to encourage its use when unbound work should be used.
Please remove this sentence, because this has already been done.

> 
> The old system_unbound_wq will be kept for a few release cycles.
> 
> Suggested-by: Tejun Heo <tj@...nel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
> ---

[...]

-- 
Best Regards,
Krzysztof