Messages in this thread Patch in this message | | | Date | Tue, 2 Dec 2014 15:43:04 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH - v3?] workqueue: allow rescuer thread to do more work. |
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Hello,
On Tue, Nov 18, 2014 at 03:27:54PM +1100, NeilBrown wrote: > @@ -2253,26 +2253,36 @@ repeat: > struct pool_workqueue, mayday_node); > struct worker_pool *pool = pwq->pool; > struct work_struct *work, *n; > + int still_needed; > > __set_current_state(TASK_RUNNING); > - list_del_init(&pwq->mayday_node); > - > - spin_unlock_irq(&wq_mayday_lock); > - > - worker_attach_to_pool(rescuer, pool); > - > - spin_lock_irq(&pool->lock); > - rescuer->pool = pool; > - > + spin_lock(&pool->lock); > /* > * Slurp in all works issued via this workqueue and > * process'em. > */ > WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); > + still_needed = need_to_create_worker(pool); > list_for_each_entry_safe(work, n, &pool->worklist, entry) > if (get_work_pwq(work) == pwq) > move_linked_works(work, scheduled, &n); > > + if (!list_empty(scheduled)) > + still_needed = 1; > + if (still_needed) { > + list_move_tail(&pwq->mayday_node, &wq->maydays); > + get_pwq(pwq); > + } else > + /* We can let go of this one now */ > + list_del_init(&pwq->mayday_node);
This seems rather convoluted. Why are we testing this before executing the work item? Can't we do this after? Isn't that - whether the wq still needs rescuing after rescuer went through it once - what we wanna know anyway? e.g. something like the following.
for_each_pwq_on_mayday_list { try to fetch work items from pwq->pool; if (none was fetched) goto remove_pwq;
execute the fetched work items;
if (need_to_create_worker()) { move the pwq to the tail; continue; }
remove_pwq: remove the pwq; }
> + > + spin_unlock(&pool->lock); > + spin_unlock_irq(&wq_mayday_lock); > + > + worker_attach_to_pool(rescuer, pool); > + > + spin_lock_irq(&pool->lock); > + rescuer->pool = pool; > process_scheduled_works(rescuer); > > /* > @@ -2293,7 +2303,7 @@ repeat: > spin_unlock_irq(&pool->lock); > > worker_detach_from_pool(rescuer, pool); > - > + cond_resched();
Also, why this addition? process_one_work() already has cond_resched_rcu_qs().
Thanks.
-- tejun
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