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workqueue: account nr_active by the backing pool

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pwq_tryinc_nr_active() and pwq_dec_nr_active() choose between the shared
per-node nr_active and the plain per-pwq one by testing
wq_node_nr_active() for NULL.

Test the backing pool with is_percpu_pool() instead, so the accounting
follows the pool that runs the work rather than the workqueue type.

No functional change.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Breno Leitao 2026-08-05 07:52:31 -07:00 committed by Tejun Heo
parent 3180ee71b6
commit b72fdc6510
1 changed files with 16 additions and 10 deletions
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26
kernel/workqueue.c
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@ -1615,9 +1615,8 @@ static bool is_percpu_pool(struct worker_pool *pool)
* @wq: workqueue of interest * @wq: workqueue of interest
* @node: NUMA node, can be %NUMA_NO_NODE * @node: NUMA node, can be %NUMA_NO_NODE
* *
* Determine wq_node_nr_active to use for @wq on @node. Returns: * Determine wq_node_nr_active to use for @wq on @node. @wq must be unbound.
* * Returns:
* - %NULL for per-cpu workqueues as they don't need to use shared nr_active.
* *
* - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE. * - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE.
* *
@ -1626,7 +1625,7 @@ static bool is_percpu_pool(struct worker_pool *pool)
static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq, static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq,
int node) int node)
{ {
if (!(wq->flags & WQ_UNBOUND)) if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
return NULL; return NULL;
if (node == NUMA_NO_NODE) if (node == NUMA_NO_NODE)
@ -1782,13 +1781,16 @@ static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill)
{ {
struct workqueue_struct *wq = pwq->wq; struct workqueue_struct *wq = pwq->wq;
struct worker_pool *pool = pwq->pool; struct worker_pool *pool = pwq->pool;
struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node); struct wq_node_nr_active *nna;
bool obtained = false; bool obtained = false;
lockdep_assert_held(&pool->lock); lockdep_assert_held(&pool->lock);
if (!nna) { /*
/* BH or per-cpu workqueue, pwq->nr_active is sufficient */ * A concurrency-managed per-cpu pool accounts nr_active per pwq, so
* pwq->nr_active against wq->max_active is sufficient.
*/
if (is_percpu_pool(pool)) {
obtained = pwq->nr_active < READ_ONCE(wq->max_active); obtained = pwq->nr_active < READ_ONCE(wq->max_active);
goto out; goto out;
} }
@ -1796,6 +1798,8 @@ static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill)
if (unlikely(pwq->plugged)) if (unlikely(pwq->plugged))
return false; return false;
nna = wq_node_nr_active(wq, pool->node);
/* /*
* Unbound workqueue uses per-node shared nr_active $nna. If @pwq is * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is
* already waiting on $nna, pwq_dec_nr_active() will maintain the * already waiting on $nna, pwq_dec_nr_active() will maintain the
@ -2013,7 +2017,7 @@ static void node_activate_pending_pwq(struct wq_node_nr_active *nna,
static void pwq_dec_nr_active(struct pool_workqueue *pwq) static void pwq_dec_nr_active(struct pool_workqueue *pwq)
{ {
struct worker_pool *pool = pwq->pool; struct worker_pool *pool = pwq->pool;
struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node); struct wq_node_nr_active *nna;
lockdep_assert_held(&pool->lock); lockdep_assert_held(&pool->lock);
@ -2024,14 +2028,16 @@ static void pwq_dec_nr_active(struct pool_workqueue *pwq)
pwq->nr_active--; pwq->nr_active--;
/* /*
* For a percpu workqueue, it's simple. Just need to kick the first * A concurrency-managed per-cpu pool only needs to kick the first
* inactive work item on @pwq itself. * inactive work item on @pwq itself.
*/ */
if (!nna) { if (is_percpu_pool(pool)) {
pwq_activate_first_inactive(pwq, false); pwq_activate_first_inactive(pwq, false);
return; return;
} }
nna = wq_node_nr_active(pwq->wq, pool->node);
/* /*
* If @pwq is for an unbound workqueue, it's more complicated because * If @pwq is for an unbound workqueue, it's more complicated because
* multiple pwqs and pools may be sharing the nr_active count. When a * multiple pwqs and pools may be sharing the nr_active count. When a