Re: [PATCH 1/1] sched: replace use of system_unbound_wq with system_dfl_wq

[Tejun Heo <tj@kernel.org>]

On Fri, Sep 05, 2025 at 11:09:28AM +0200, Marco Crivellari wrote:
> 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 consistentcy 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.
> 
> Adding system_dfl_wq to encourage its use when unbound work should be used.
> 
> queue_work() / queue_delayed_work() / mod_delayed_work() will now use the
> new unbound wq: whether the user still use the old wq a warn will be
> printed along with a wq redirect to the new one.
> 
> The old system_unbound_wq will be kept for a few release cycles.
> 
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun