Commit 2817e6fa authored by Marco Crivellari's avatar Marco Crivellari Committed by Rafael J. Wysocki
Browse files

ACPI: thermal: Add WQ_PERCPU 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>
[ rjw: Subject adjustment ]
Link: https://patch.msgid.link/20251030154739.262582-6-marco.crivellari@suse.com


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent ec4291f5

drivers/acpi/thermal.c

+2 −1
Original line number Diff line number Diff line
@@ -1060,7 +1060,8 @@ static int __init acpi_thermal_init(void) 
	}



	acpi_thermal_pm_queue = alloc_workqueue("acpi_thermal_pm",

						WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);

						WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_PERCPU,

						0);

	if (!acpi_thermal_pm_queue)

		return -ENODEV;