diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/workqueue.c | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7f9225936cd9..64fe81f30e85 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3461,10 +3461,37 @@ static bool assign_rescuer_work(struct pool_workqueue *pwq, struct worker *rescu struct work_struct *cursor = &pwq->mayday_cursor; struct work_struct *work, *n; - /* need rescue? */ - if (!pwq->nr_active || !need_to_create_worker(pool)) + /* have work items to rescue? */ + if (!pwq->nr_active) return false; + /* need rescue? */ + if (!need_to_create_worker(pool)) { + /* + * The pool has idle workers and doesn't need the rescuer, so it + * could simply return false here. + * + * However, the memory pressure might not be fully relieved. + * In PERCPU pool with concurrency enabled, having idle workers + * does not necessarily mean memory pressure is gone; it may + * simply mean regular workers have woken up, completed their + * work, and gone idle again due to concurrency limits. + * + * In this case, those working workers may later sleep again, + * the pool may run out of idle workers, and it will have to + * allocate new ones and wait for the timer to send mayday, + * causing unnecessary delay - especially if memory pressure + * was never resolved throughout. + * + * Do more work if memory pressure is still on to reduce + * relapse, using (pool->flags & POOL_MANAGER_ACTIVE), though + * not precisely, unless there are other PWQs needing help. + */ + if (!(pool->flags & POOL_MANAGER_ACTIVE) || + !list_empty(&pwq->wq->maydays)) + return false; + } + /* search from the start or cursor if available */ if (list_empty(&cursor->entry)) work = list_first_entry(&pool->worklist, struct work_struct, entry); |