From: Marco Crivellari Date: Thu, 30 Oct 2025 15:47:39 +0000 (+0100) Subject: ACPI: thermal: Add WQ_PERCPU to alloc_workqueue() users X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2817e6fa84ac8fe54efc208f5676698275ff6412;p=thirdparty%2Fkernel%2Flinux.git 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: Tejun Heo Signed-off-by: Marco Crivellari [ rjw: Subject adjustment ] Link: https://patch.msgid.link/20251030154739.262582-6-marco.crivellari@suse.com Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c index 8537395b417b0..a511f9ea02676 100644 --- a/drivers/acpi/thermal.c +++ b/drivers/acpi/thermal.c @@ -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;