On Fri Nov 7 15:13:03 2025 +0100, Marco Crivellari wrote:
> Currently if a user enqueues 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.
>
> alloc_workqueue() treats all queues as per-CPU by default, while unbound
> workqueues must opt-in via WQ_UNBOUND.
>
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where theyâre needed and
> reducing noise when CPUs are isolated.
>
> This continues the effort to refactor workqueue APIs, which began with
> the introduction of new workqueues and a new alloc_workqueue flag in:
>
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
>
> This change adds a new WQ_PERCPU flag to explicitly request
> alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
>
> With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
> any alloc_workqueue() caller that doesnât explicitly specify WQ_UNBOUND
> must now use WQ_PERCPU.
>
> Once migration is complete, WQ_UNBOUND can be removed and unbound will
> become the implicit default.
>
> Suggested-by: Tejun Heo <[email protected]>
> Signed-off-by: Marco Crivellari <[email protected]>
> Reviewed-by: AngeloGioacchino Del Regno
> <[email protected]>
> Signed-off-by: Nicolas Dufresne <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
index 6d26d4aa1eef..f20d2ed1f2bb 100644
--- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
+++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
@@ -268,14 +268,16 @@ static int mdp_probe(struct platform_device *pdev)
goto err_free_mutex;
}
- mdp->job_wq = alloc_workqueue(MDP_MODULE_NAME, WQ_FREEZABLE, 0);
+ mdp->job_wq = alloc_workqueue(MDP_MODULE_NAME,
+ WQ_FREEZABLE | WQ_PERCPU, 0);
if (!mdp->job_wq) {
dev_err(dev, "Unable to create job workqueue\n");
ret = -ENOMEM;
goto err_deinit_comp;
}
- mdp->clock_wq = alloc_workqueue(MDP_MODULE_NAME "-clock", WQ_FREEZABLE,
+ mdp->clock_wq = alloc_workqueue(MDP_MODULE_NAME "-clock",
+ WQ_FREEZABLE | WQ_PERCPU,
0);
if (!mdp->clock_wq) {
dev_err(dev, "Unable to create clock workqueue\n");
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