[PATCH v2] s390/hiperdispatch: use system_dfl_wq to reschedule hd_capacity_work

[PATCH v2] s390/hiperdispatch: use system_dfl_wq to reschedule hd_capacity_work

[Euan Bourke]

In hd_enable_hiperdispatch(), hd_capacity_work is scheduled on
system_dfl_wq, however the work function reschedules itself with
schedule_delayed_work(), which uses system_percpu_wq.

Hiperdispatch does not benefit from using the percpu workqueue. Use
queue_delayed_work() with system_dfl_wq for consistency.

Changing the workqueue from system_percpu_wq to system_dfl_wq causes no
functional changes.

Signed-off-by: Euan Bourke <euan@linux.ibm.com>
---
v2:
- use queue_delayed_work() instead of mod_delayed_work()

 arch/s390/kernel/hiperdispatch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kernel/hiperdispatch.c b/arch/s390/kernel/hiperdispatch.c
index 217206522266..8494823559b1 100644
--- a/arch/s390/kernel/hiperdispatch.c
+++ b/arch/s390/kernel/hiperdispatch.c
@@ -265,7 +265,7 @@ static void hd_capacity_work_fn(struct work_struct *work)
 	}
 	trace_s390_hd_work_fn(steal_percentage, hd_entitled_cores, hd_high_capacity_cores);
 	mutex_unlock(&smp_cpu_state_mutex);
-	schedule_delayed_work(&hd_capacity_work, HD_DELAY_INTERVAL);
+	queue_delayed_work(system_dfl_wq, &hd_capacity_work, HD_DELAY_INTERVAL);
 }
 
 static int hiperdispatch_ctl_handler(const struct ctl_table *ctl, int write,
-- 
2.54.0

Re: [PATCH v2] s390/hiperdispatch: use system_dfl_wq to reschedule hd_capacity_work

[sashiko-bot]

> In hd_enable_hiperdispatch(), hd_capacity_work is scheduled on
> system_dfl_wq, however the work function reschedules itself with
> schedule_delayed_work(), which uses system_percpu_wq.
> 
> Hiperdispatch does not benefit from using the percpu workqueue. Use
> queue_delayed_work() with system_dfl_wq for consistency.
> 
> Changing the workqueue from system_percpu_wq to system_dfl_wq causes no
> functional changes.
> 
> Signed-off-by: Euan Bourke <euan@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911091309.1238604-1-euan@linux.ibm.com?part=1

Re: [PATCH v2] s390/hiperdispatch: use system_dfl_wq to reschedule hd_capacity_work

[Mete Durlu]

On 11/09/2026 11:13, Euan Bourke wrote:
> In hd_enable_hiperdispatch(), hd_capacity_work is scheduled on
> system_dfl_wq, however the work function reschedules itself with
> schedule_delayed_work(), which uses system_percpu_wq.
> 
> Hiperdispatch does not benefit from using the percpu workqueue. Use
> queue_delayed_work() with system_dfl_wq for consistency.
> 
> Changing the workqueue from system_percpu_wq to system_dfl_wq causes no
> functional changes.
> 
> Signed-off-by: Euan Bourke <euan@linux.ibm.com>
> ---
> v2:
> - use queue_delayed_work() instead of mod_delayed_work()
> 
>   arch/s390/kernel/hiperdispatch.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
This disparity is first introduced at;
commit 72105fc1c1cb ("s390: Replace use of system_wq with system_dfl_wq")

I must have missed that schedule_delayed_work() always moves the
work item from its original work queue to system_percpu_wq.

Thanks for the patch and feel free to put my r-b and tested-by
as it looks good and tela test cases for hiperdispatch show no
regression.

Tested-by: Mete Durlu <meted@linux.ibm.com>
Reviewed-by: Mete Durlu <meted@linux.ibm.com>