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

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[ Upstream commit c5404d4e6df6faba1007544b5f4e62c7c14416dd ]

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: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Stable-dep-of: 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement for unbound workqueues")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tejun Heo 2024-01-29 08:11:24 -10:00 committed by Sasha Levin
parent 4023a2d950
commit 5f99fee6f2
1 changed files with 19 additions and 12 deletions
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31
kernel/workqueue.c
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@ -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);
for_each_pwq(pwq, wq) {
unsigned long flags;
/*
* Round-robin through pwq's activating the first inactive work item
* until max_active is filled.
*/
do {
struct pool_workqueue *pwq;
/* this function can be called during early boot w/ irq disabled */
raw_spin_lock_irqsave(&pwq->pool->lock, flags);
activated = false;
for_each_pwq(pwq, wq) {
unsigned long flags;
while (pwq_activate_first_inactive(pwq))
;
kick_pool(pwq->pool);
raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
}
/* can be called during early boot w/ irq disabled */
raw_spin_lock_irqsave(&pwq->pool->lock, flags);
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)