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async: Use a dedicated unbound workqueue with raised min_active 

Async can schedule a number of interdependent work items. However, since
5797b1c189 ("workqueue: Implement system-wide nr_active enforcement for
unbound workqueues"), unbound workqueues have separate min_active which sets
the number of interdependent work items that can be handled. This default
value is 8 which isn't sufficient for async and can lead to stalls during
resume from suspend in some cases.

Let's use a dedicated unbound workqueue with raised min_active.

Link: http://lkml.kernel.org/r/708a65cc-79ec-44a6-8454-a93d0f3114c3@samsung.com
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2024-02-08 14:14:16 -10:00
parent 8f172181f2
commit bf52b1ac6a
3 changed files with 18 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/async.h
View File

@ -120,4 +120,5 @@ extern void async_synchronize_cookie(async_cookie_t cookie);
extern void async_synchronize_cookie_domain(async_cookie_t cookie,
struct async_domain *domain);
extern bool current_is_async(void);
extern void async_init(void);
#endif

1
init/main.c
View File

@ -1545,6 +1545,7 @@ static noinline void __init kernel_init_freeable(void)
sched_init_smp();
workqueue_init_topology();
async_init();
padata_init();
page_alloc_init_late();

17
kernel/async.c
View File

@ -64,6 +64,7 @@ static async_cookie_t next_cookie = 1;
static LIST_HEAD(async_global_pending); /* pending from all registered doms */
static ASYNC_DOMAIN(async_dfl_domain);
static DEFINE_SPINLOCK(async_lock);
static struct workqueue_struct *async_wq;
struct async_entry {
struct list_head domain_list;
@ -174,7 +175,7 @@ static async_cookie_t __async_schedule_node_domain(async_func_t func,
spin_unlock_irqrestore(&async_lock, flags);
/* schedule for execution */
queue_work_node(node, system_unbound_wq, &entry->work);
queue_work_node(node, async_wq, &entry->work);
return newcookie;
}
@ -345,3 +346,17 @@ bool current_is_async(void)
return worker && worker->current_func == async_run_entry_fn;
}
EXPORT_SYMBOL_GPL(current_is_async);
void __init async_init(void)
{
/*
* Async can schedule a number of interdependent work items. However,
* unbound workqueues can handle only upto min_active interdependent
* work items. The default min_active of 8 isn't sufficient for async
* and can lead to stalls. Let's use a dedicated workqueue with raised
* min_active.
*/
async_wq = alloc_workqueue("async", WQ_UNBOUND, 0);
BUG_ON(!async_wq);
workqueue_set_min_active(async_wq, WQ_DFL_ACTIVE);
}