diff options
| author | Marco Crivellari <marco.crivellari@suse.com> | 2025-09-14 15:44:26 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-09-16 10:33:53 -1000 |
| commit | dadb3ebcf395ebee3626d88ac7e5e234f15bae2c (patch) | |
| tree | d34885da2f8e199a69dc16e89491d74a81d2339f /include/linux/workqueue.h | |
| parent | a2be943b46b4a7478ea8ddf9bb8e5251c59fceb7 (diff) | |
workqueue: 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 'include/linux/workqueue.h')
| -rw-r--r-- | include/linux/workqueue.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index b6834b7aee4b..71a9900c03c7 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -410,7 +410,7 @@ enum wq_flags { __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */ /* BH wq only allows the following flags */ - __WQ_BH_ALLOWS = WQ_BH | WQ_HIGHPRI, + __WQ_BH_ALLOWS = WQ_BH | WQ_HIGHPRI | WQ_PERCPU, }; enum wq_consts { @@ -570,7 +570,7 @@ alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags, int max_active, alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args) #define create_workqueue(name) \ - alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name)) + alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_PERCPU, 1, (name)) #define create_freezable_workqueue(name) \ alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \ WQ_MEM_RECLAIM, 1, (name)) |