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.
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 they’re needed and reducing noise when CPUs are isolated. 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 doesn’t 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]> --- drivers/gpu/drm/nouveau/nouveau_drm.c | 2 +- drivers/gpu/drm/nouveau/nouveau_sched.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index 1527b801f013..5a2970ef27d4 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -631,7 +631,7 @@ nouveau_drm_device_init(struct nouveau_drm *drm) struct drm_device *dev = drm->dev; int ret; - drm->sched_wq = alloc_workqueue("nouveau_sched_wq_shared", 0, + drm->sched_wq = alloc_workqueue("nouveau_sched_wq_shared", WQ_PERCPU, WQ_MAX_ACTIVE); if (!drm->sched_wq) return -ENOMEM; diff --git a/drivers/gpu/drm/nouveau/nouveau_sched.c b/drivers/gpu/drm/nouveau/nouveau_sched.c index e60f7892f5ce..79cf157ab2a5 100644 --- a/drivers/gpu/drm/nouveau/nouveau_sched.c +++ b/drivers/gpu/drm/nouveau/nouveau_sched.c @@ -416,7 +416,8 @@ nouveau_sched_init(struct nouveau_sched *sched, struct nouveau_drm *drm, int ret; if (!wq) { - wq = alloc_workqueue("nouveau_sched_wq_%d", 0, WQ_MAX_ACTIVE, + wq = alloc_workqueue("nouveau_sched_wq_%d", WQ_PERCPU, + WQ_MAX_ACTIVE, current->pid); if (!wq) return -ENOMEM; -- 2.51.0
