Messages in this thread Patch in this message |  | | From | Marco Crivellari <> | | Subject | [PATCH 2/3] mm: replace use of system_wq with system_percpu_wq | | Date | Fri, 5 Sep 2025 11:03:22 +0200 |
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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_wq is a per-CPU worqueue, yet nothing in its name tells about that CPU affinity constraint, which is very often not required by users. Make it clear by adding a system_percpu_wq to all the mm subsystem.
The old wq will be kept for a few release cylces.
Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com> --- mm/backing-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index e9f9fdcfe052..7e672424f928 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -966,7 +966,7 @@ static int __init cgwb_init(void) { /* * There can be many concurrent release work items overwhelming - * system_wq. Put them in a separate wq and limit concurrency. + * system_percpu_wq. Put them in a separate wq and limit concurrency. * There's no point in executing many of these in parallel. */ cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); -- 2.51.0
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