Commit bf52b1ac authored by Tejun Heo's avatar Tejun Heo
Browse files

async: Use a dedicated unbound workqueue with raised min_active 

Async can schedule a number of interdependent work items. However, since
5797b1c1 ("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: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 8f172181

include/linux/async.h

+1 −0
Original line number Diff line number Diff line
@@ -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

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -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();

kernel/async.c

+16 −1
Original line number Diff line number Diff line
@@ -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);

}