From a5d71f011ee1f211e437333555fd981e040c146c Mon Sep 17 00:00:00 2001 From: Marco Crivellari Date: Fri, 5 Sep 2025 10:57:01 +0200 Subject: crypto: cryptd - WQ_PERCPU added to alloc_workqueue users MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 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 patch adds a new WQ_PERCPU flag to explicitly request the use of the per-CPU behavior. Both flags coexist for one release cycle to allow callers to transition their calls. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. 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. All existing users have been updated accordingly. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Herbert Xu --- crypto/cryptd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'crypto/cryptd.c') diff --git a/crypto/cryptd.c b/crypto/cryptd.c index efff54e707cb..cd38f4676176 100644 --- a/crypto/cryptd.c +++ b/crypto/cryptd.c @@ -1115,7 +1115,8 @@ static int __init cryptd_init(void) { int err; - cryptd_wq = alloc_workqueue("cryptd", WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE, + cryptd_wq = alloc_workqueue("cryptd", + WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE | WQ_PERCPU, 1); if (!cryptd_wq) return -ENOMEM; -- cgit