Commit e60c5583 authored by Marco Crivellari's avatar Marco Crivellari Committed by Leon Romanovsky
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarMarco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20251101163121.78400-3-marco.crivellari@suse.com


Signed-off-by: default avatarLeon Romanovsky <leon@kernel.org>
parent f673fb34

drivers/infiniband/core/cm.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

drivers/infiniband/core/device.c

+2 −2
Original line number Diff line number Diff line
@@ -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;