[PATCH] cgroup/cpuset: Replace use of system_unbound_wq with system_dfl_wq

[PATCH] cgroup/cpuset: Replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

This patch continues the effort to refactor workqueue APIs, which has begun
with the changes introducing new workqueues and a new alloc_workqueue flag:

   commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
   commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

The point of the refactoring is to eventually alter the default behavior of
workqueues to become unbound by default so that their workload placement is
optimized by the scheduler.

Before that to happen, workqueue users must be converted to the better named
new workqueues with no intended behaviour changes:

   system_wq -> system_percpu_wq
   system_unbound_wq -> system_dfl_wq

This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
removed in the future.

Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
---
 kernel/cgroup/cpuset.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index e200de7c60b6..b399f5d0a158 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3937,7 +3937,7 @@ static void cpuset_handle_hotplug(void)
 	 * item at all, this is not a problem.
 	 */
 	if (update_housekeeping || force_sd_rebuild)
-		queue_work(system_unbound_wq, &hk_sd_work);
+		queue_work(system_dfl_wq, &hk_sd_work);
 
 	free_tmpmasks(ptmp);
 }
-- 
2.53.0

Re: [PATCH] cgroup/cpuset: Replace use of system_unbound_wq with system_dfl_wq

[Waiman Long]

On 3/13/26 11:45 AM, Marco Crivellari wrote:
> This patch continues the effort to refactor workqueue APIs, which has begun
> with the changes introducing new workqueues and a new alloc_workqueue flag:
>
>     commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
>     commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
>
> The point of the refactoring is to eventually alter the default behavior of
> workqueues to become unbound by default so that their workload placement is
> optimized by the scheduler.
>
> Before that to happen, workqueue users must be converted to the better named
> new workqueues with no intended behaviour changes:
>
>     system_wq -> system_percpu_wq
>     system_unbound_wq -> system_dfl_wq
>
> This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
> removed in the future.
>
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
> ---
>   kernel/cgroup/cpuset.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index e200de7c60b6..b399f5d0a158 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3937,7 +3937,7 @@ static void cpuset_handle_hotplug(void)
>   	 * item at all, this is not a problem.
>   	 */
>   	if (update_housekeeping || force_sd_rebuild)
> -		queue_work(system_unbound_wq, &hk_sd_work);
> +		queue_work(system_dfl_wq, &hk_sd_work);
>   
>   	free_tmpmasks(ptmp);
>   }

Thanks for the patch, but there is another patch that makes the
same change as part of a larger fix to the cpuset code. See commit
ca174c705db5 ("cgroup/cpuset: Call rebuild_sched_domains() directly in
hotplug")  in the cgroup tree.

Thanks,
Longman

Re: [PATCH] cgroup/cpuset: Replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

On Fri, Mar 13, 2026 at 5:01 PM Waiman Long <longman@redhat.com> wrote:
> [...]
>
> Thanks for the patch, but there is another patch that makes the
> same change as part of a larger fix to the cpuset code. See commit
> ca174c705db5 ("cgroup/cpuset: Call rebuild_sched_domains() directly in
> hotplug")  in the cgroup tree.

Aha, thank you!


-- 

Marco Crivellari

L3 Support Engineer