Hi,

=== Current situation: problems ===

Let's consider a nohz_full system with isolated CPUs: wq_unbound_cpumask is
set to the housekeeping CPUs, for !WQ_UNBOUND the local CPU is selected.

This leads to different scenarios if a work item is scheduled on an
isolated CPU where "delay" value is 0 or greater then 0:
        schedule_delayed_work(, 0);

This will be handled by __queue_work() that will queue the work item on the
current local (isolated) CPU, while:

        schedule_delayed_work(, 1);

Will move the timer on an housekeeping CPU, and schedule the work there.

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.

=== Recent changes to the WQ API ===

The following, address the recent changes in the Workqueue API:

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

The old workqueues will be removed in a future release cycle.

=== Introduced Changes by this series ===

1) [P 1-2]  Replace uses of system_wq and system_unbound_wq

    system_wq is a per-CPU workqueue, but his name is not clear.
    system_unbound_wq is to be used when locality is not required.

    Because of that, system_wq has been replaced with system_percpu_wq, and
    system_unbound_wq has been replaced with system_dfl_wq.

	The new wq(s) keep the same old behavior.


Thanks!


Marco Crivellari (2):
  drm/rockchip: replace use of system_unbound_wq with system_dfl_wq
  drm/rockchip: replace use of system_wq with system_percpu_wq

 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 4 ++--
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c    | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

-- 
2.51.0

On Fri, 31 Oct 2025 11:48:44 +0100, Marco Crivellari wrote:
> === Current situation: problems ===
> 
> Let's consider a nohz_full system with isolated CPUs: wq_unbound_cpumask is
> set to the housekeeping CPUs, for !WQ_UNBOUND the local CPU is selected.
> 
> This leads to different scenarios if a work item is scheduled on an
> isolated CPU where "delay" value is 0 or greater then 0:
>         schedule_delayed_work(, 0);
> 
> [...]

Applied, thanks!

[1/2] drm/rockchip: replace use of system_unbound_wq with system_dfl_wq
      commit: 0650f4909af2bafe49322c91dd8dd0f68abfdf4f
[2/2] drm/rockchip: replace use of system_wq with system_percpu_wq
      commit: ab8559d44de5750e03778c42311aec8dd41a61f5

Best regards,
-- 
Heiko Stuebner <heiko@sntech.de>

On Fri, Jan 9, 2026 at 8:25 PM Heiko Stuebner <heiko@sntech.de> wrote:
> [...]
>
> Applied, thanks!
>
> [1/2] drm/rockchip: replace use of system_unbound_wq with system_dfl_wq
>       commit: 0650f4909af2bafe49322c91dd8dd0f68abfdf4f
> [2/2] drm/rockchip: replace use of system_wq with system_percpu_wq
>       commit: ab8559d44de5750e03778c42311aec8dd41a61f5

Thank you!

-- 

Marco Crivellari

L3 Support Engineer

Hi,

On Fri, Oct 31, 2025 at 11:48 AM Marco Crivellari
<marco.crivellari@suse.com> wrote:
> Marco Crivellari (2):
>   drm/rockchip: replace use of system_unbound_wq with system_dfl_wq
>   drm/rockchip: replace use of system_wq with system_percpu_wq
>
>  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 4 ++--
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.c    | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)

Gentle ping about this.

Thanks!

-- 

Marco Crivellari

L3 Support Engineer, Technology & Product