On 12/04/2014 02:02 AM, Tejun Heo wrote:
> So, something like the following. Only compile tested. I'll test it
> and post proper patches w/ due credits.
>
> Thanks.
>
> Index: work/kernel/workqueue.c
> ===================================================================
> --- work.orig/kernel/workqueue.c
> +++ work/kernel/workqueue.c
> @@ -1804,8 +1804,8 @@ static void pool_mayday_timeout(unsigned
> struct worker_pool *pool = (void *)__pool;
> struct work_struct *work;
>
> - spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
> - spin_lock(&pool->lock);
> + spin_lock_irq(&pool->lock);
> + spin_lock(&wq_mayday_lock); /* for wq->maydays */
>
> if (need_to_create_worker(pool)) {
> /*
> @@ -1818,8 +1818,8 @@ static void pool_mayday_timeout(unsigned
> send_mayday(work);
> }
>
> - spin_unlock(&pool->lock);
> - spin_unlock_irq(&wq_mayday_lock);
> + spin_unlock(&wq_mayday_lock);
> + spin_unlock_irq(&pool->lock);
>
> mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
> }
> @@ -2248,12 +2248,29 @@ repeat:
> * Slurp in all works issued via this workqueue and
> * process'em.
> */
> - WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
> + WARN_ON_ONCE(!list_empty(scheduled));
> list_for_each_entry_safe(work, n, &pool->worklist, entry)
> if (get_work_pwq(work) == pwq)
> move_linked_works(work, scheduled, &n);
>
> - process_scheduled_works(rescuer);
> + if (!list_empty(scheduled)) {
> + process_scheduled_works(rescuer);
> +
> + /*
> + * The above execution of rescued work items could
> + * have created more to rescue through
> + * pwq_activate_first_delayed() or chained
> + * queueing. Let's put @pwq back on mayday list so
> + * that such back-to-back work items, which may be
> + * being used to relieve memory pressure, don't
> + * incur MAYDAY_INTERVAL delay inbetween.
> + */
> + if (need_to_create_worker(pool)) {
> + spin_lock(&wq_mayday_lock);
> + list_move_tail(&pwq->mayday_node, &wq->maydays);
how about the pwq is empty now? and ...
> + spin_unlock(&wq_mayday_lock);
> + }
> + }
>
> /*
> * Put the reference grabbed by send_mayday(). @pool won't
and the pwq is scheduled free here>
>
--
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