On Wed, 3 Dec 2014 23:31:16 +0100 Dongsu Park <[email protected]> wrote:
> Hi Tejun,
>
> On 03.12.2014 13:02, Tejun Heo wrote:
> > So, something like the following. Only compile tested. I'll test it
> > and post proper patches w/ due credits.
>
> I have been already satisfied with Neil's patch,
> but your patch looks indeed a lot cleaner, I like it.
> I just compiled and tested it shortly, which seems to work.
> Though there's one nitpick. (see below)
>
> > 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);
>
> Does it need to call get_pwq(pwq), doesn't it?
Yes, I think it does.
Swapping the order of the locks make it so much nicer, doesn't it!!
Thanks,
NeilBrown
>
> Thanks,
> Dongsu
>
> > + list_move_tail(&pwq->mayday_node, &wq->maydays);
> > + spin_unlock(&wq_mayday_lock);
> > + }
> > + }
> >
> > /*
> > * Put the reference grabbed by send_mayday(). @pool won't
> >
> > --
> > tejun
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