Messages in this thread | | | Subject | Re: [RFC][PATCH 2/3] sched, workqueue: Move WQ-sleeper wakeup | From | Peter Zijlstra <> | Date | Wed, 22 Jun 2011 11:27:28 +0200 |
| |
On Wed, 2011-06-22 at 11:24 +0200, Tejun Heo wrote: > Hello, Peter. > > On Wed, Jun 22, 2011 at 01:34:46AM +0200, Peter Zijlstra wrote: > > -/** > > * wake_up_process - Wake up a specific process > > * @p: The process to be woken up. > > * > > @@ -4215,6 +4181,19 @@ static inline void sched_submit_work(voi > > > > if (tsk->state && !(preempt_count() & PREEMPT_ACTIVE)) { > > /* > > + * If a worker went to sleep, notify and ask workqueue > > + * whether it wants to wake up a task to maintain > > + * concurrency. > > + */ > > + if (tsk->flags & PF_WQ_WORKER) { > > + struct task_struct *to_wakeup; > > + > > + to_wakeup = wq_worker_sleeping(tsk, smp_processor_id()); > > + if (to_wakeup) > > + wake_up_process(to_wakeup); > > + } > > + > > + /* > > Preemption could still be enabled here, right? What prevents > preemtion kicking after wq_worker_sleeping() and do it again thus > breaking nr_running tracking.
Aren't all PF_WQ_WORKER threads cpu-bound?
> > * If we are going to sleep and we have plugged IO > > * queued, make sure to submit it to avoid deadlocks. > > */ > > @@ -4256,19 +4235,6 @@ asmlinkage void __sched schedule(void) > > } else { > > deactivate_task(rq, prev, DEQUEUE_SLEEP); > > prev->on_rq = 0; > > - > > - /* > > - * If a worker went to sleep, notify and ask workqueue > > - * whether it wants to wake up a task to maintain > > - * concurrency. > > - */ > > - if (prev->flags & PF_WQ_WORKER) { > > - struct task_struct *to_wakeup; > > - > > - to_wakeup = wq_worker_sleeping(prev, cpu); > > - if (to_wakeup) > > - try_to_wake_up_local(to_wakeup); > > - } > > Similarly, the if the 'if {}' part of the above if/else is taken, the > task never goes to sleep and nr_running will again be broken.
Bah, indeed, I forgot about that, 2am isn't the best of times to do these things.
| |