Commit c5404d4e authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: Make wq_adjust_max_active() round-robin pwqs while activating 



wq_adjust_max_active() needs to activate work items after max_active is
increased. Previously, it did that by visiting each pwq once activating all
that could be activated. While this makes sense with per-pwq nr_active,
nr_active will be shared across multiple pwqs for unbound wqs. Then, we'd
want to round-robin through pwqs to be fairer.

In preparation, this patch makes wq_adjust_max_active() round-robin pwqs
while activating. While the activation ordering changes, this shouldn't
cause user-noticeable behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <jiangshanlai@gmail.com>
parent 1c270b79

kernel/workqueue.c

+19 −12
Original line number Diff line number Diff line
@@ -4710,7 +4710,7 @@ static int init_rescuer(struct workqueue_struct *wq) 
 */

static void wq_adjust_max_active(struct workqueue_struct *wq)

{

	struct pool_workqueue *pwq;

	bool activated;



	lockdep_assert_held(&wq->mutex);
@@ -4730,19 +4730,26 @@ static void wq_adjust_max_active(struct workqueue_struct *wq) 
	 */

	WRITE_ONCE(wq->max_active, wq->saved_max_active);



	/*

	 * Round-robin through pwq's activating the first inactive work item

	 * until max_active is filled.

	 */

	do {

		struct pool_workqueue *pwq;



		activated = false;

		for_each_pwq(pwq, wq) {

			unsigned long flags;



		/* this function can be called during early boot w/ irq disabled */

			/* can be called during early boot w/ irq disabled */

			raw_spin_lock_irqsave(&pwq->pool->lock, flags);



		while (pwq_activate_first_inactive(pwq))

			;



			if (pwq_activate_first_inactive(pwq)) {

				activated = true;

				kick_pool(pwq->pool);



			}

			raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);

		}

	} while (activated);

}



__printf(1, 4)