From: Marco Crivellari Date: Sat, 1 Nov 2025 16:31:14 +0000 (+0100) Subject: RDMA/mlx4: WQ_PERCPU added to alloc_workqueue users X-Git-Tag: v6.19-rc1~130^2~52 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5267feda50680c73e33b118dbebfb961d6a864bd;p=thirdparty%2Fkernel%2Flinux.git RDMA/mlx4: 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. CC: Yishai Hadas Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Link: https://patch.msgid.link/20251101163121.78400-5-marco.crivellari@suse.com Signed-off-by: Leon Romanovsky --- diff --git a/drivers/infiniband/hw/mlx4/cm.c b/drivers/infiniband/hw/mlx4/cm.c index 12b481d138cf4..03aacd5268605 100644 --- a/drivers/infiniband/hw/mlx4/cm.c +++ b/drivers/infiniband/hw/mlx4/cm.c @@ -591,7 +591,7 @@ void mlx4_ib_cm_paravirt_clean(struct mlx4_ib_dev *dev, int slave) int mlx4_ib_cm_init(void) { - cm_wq = alloc_workqueue("mlx4_ib_cm", 0, 0); + cm_wq = alloc_workqueue("mlx4_ib_cm", WQ_PERCPU, 0); if (!cm_wq) return -ENOMEM;