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.
Showing the changes to kernel/workqueue.c (1 of 1 file). Show all
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| @@ -4710,7 +4710,7 @@ static int init_rescuer(struct workqueue_struct *wq) · 4709 unmodified lines | |||
| 4710 | */ | 4710 | */ |
| 4711 | static void wq_adjust_max_active(struct workqueue_struct *wq) | 4711 | static void wq_adjust_max_active(struct workqueue_struct *wq) |
| 4712 | { | 4712 | { |
| 4713 | struct pool_workqueue *pwq; | 4713 | bool activated; |
| 4714 | 4714 | ||
| 4715 | lockdep_assert_held(&wq->mutex); | 4715 | lockdep_assert_held(&wq->mutex); |
| 4716 | 4716 | ||
| @@ -4730,19 +4730,26 @@ static void wq_adjust_max_active(struct workqueue_struct *wq) · 13 unmodified lines | |||
| 4730 | */ | 4730 | */ |
| 4731 | WRITE_ONCE(wq->max_active, wq->saved_max_active); | 4731 | WRITE_ONCE(wq->max_active, wq->saved_max_active); |
| 4732 | 4732 | ||
| 4733 | for_each_pwq(pwq, wq) { | 4733 | /* |
| 4734 | unsigned long flags; | 4734 | * Round-robin through pwq's activating the first inactive work item |
| 4735 | 4735 | * until max_active is filled. | |
| 4736 | /* this function can be called during early boot w/ irq disabled */ | 4736 | */ |
| 4737 | raw_spin_lock_irqsave(&pwq->pool->lock, flags); | 4737 | do { |
| 4738 | 4738 | struct pool_workqueue *pwq; | |
| 4739 | while (pwq_activate_first_inactive(pwq)) | ||
| 4740 | ; | ||
| 4741 | 4739 | ||
| 4742 | kick_pool(pwq->pool); | 4740 | activated = false; |
| 4741 | for_each_pwq(pwq, wq) { | ||
| 4742 | unsigned long flags; | ||
| 4743 | 4743 | ||
| 4744 | raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); | 4744 | /* can be called during early boot w/ irq disabled */ |
| 4745 | } | 4745 | raw_spin_lock_irqsave(&pwq->pool->lock, flags); |
| 4746 | if (pwq_activate_first_inactive(pwq)) { | ||
| 4747 | activated = true; | ||
| 4748 | kick_pool(pwq->pool); | ||
| 4749 | } | ||
| 4750 | raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); | ||
| 4751 | } | ||
| 4752 | } while (activated); | ||
| 4746 | } | 4753 | } |
| 4747 | 4754 | ||
| 4748 | __printf(1, 4) | 4755 | __printf(1, 4) |