diff options
| author | Marco Crivellari <marco.crivellari@suse.com> | 2025-09-05 10:54:36 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-09-05 06:40:25 -1000 |
| commit | 7fa33aa3b001758352c8d0abb9f212a5bb9ed46a (patch) | |
| tree | c6ea3e3ae4959ace1782be0faaef91d0e2ce7b6a /kernel | |
| parent | d6256771d106172cf7b6e6bfc49f5a1f2ff8c76c (diff) | |
cgroup: 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 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 <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cgroup-v1.c | 2 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 763343fbd5a1..0a23b65de013 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -1326,7 +1326,7 @@ static int __init cgroup1_wq_init(void) * Cap @max_active to 1 too. */ cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", - 0, 1); + WQ_PERCPU, 1); BUG_ON(!cgroup_pidlist_destroy_wq); return 0; } diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 06a9b4a17d41..99d3b6c0f328 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6346,7 +6346,7 @@ static int __init cgroup_wq_init(void) * We would prefer to do this in cgroup_init() above, but that * is called before init_workqueues(): so leave this until after. */ - cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); + cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", WQ_PERCPU, 1); BUG_ON(!cgroup_destroy_wq); return 0; } |