From: Marco Crivellari Date: Sat, 1 Nov 2025 16:31:12 +0000 (+0100) Subject: RDMA/core: WQ_PERCPU added to alloc_workqueue users X-Git-Tag: v6.19-rc1~130^2~54 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e60c5583b661da65b09bfd6ae91126607397490e;p=thirdparty%2Fkernel%2Flinux.git RDMA/core: WQ_PERCPU added to alloc_workqueue users 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 Signed-off-by: Marco Crivellari Link: https://patch.msgid.link/20251101163121.78400-3-marco.crivellari@suse.com Signed-off-by: Leon Romanovsky --- diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c index 2a36a93459592..024df6ee239d9 100644 --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -4517,7 +4517,7 @@ static int __init ib_cm_init(void) get_random_bytes(&cm.random_id_operand, sizeof cm.random_id_operand); INIT_LIST_HEAD(&cm.timewait_list); - cm.wq = alloc_workqueue("ib_cm", 0, 1); + cm.wq = alloc_workqueue("ib_cm", WQ_PERCPU, 1); if (!cm.wq) { ret = -ENOMEM; goto error2; diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index b4f3c835844a9..13e8a1714bbd7 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -3021,7 +3021,7 @@ static int __init ib_core_init(void) { int ret = -ENOMEM; - ib_wq = alloc_workqueue("infiniband", 0, 0); + ib_wq = alloc_workqueue("infiniband", WQ_PERCPU, 0); if (!ib_wq) return -ENOMEM; @@ -3031,7 +3031,7 @@ static int __init ib_core_init(void) goto err; ib_comp_wq = alloc_workqueue("ib-comp-wq", - WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_SYSFS, 0); + WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_SYSFS | WQ_PERCPU, 0); if (!ib_comp_wq) goto err_unbound;