lkml.org 
[lkml]   [2011]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: workqueue_set_max_active(wq, 0)?
Hello, Johannes.

On Thu, Dec 15, 2011 at 04:38:12PM +0100, Johannes Berg wrote:
> --- a/kernel/workqueue.c 2011-12-10 17:32:26.000000000 +0100
> +++ b/kernel/workqueue.c 2011-12-15 16:36:06.000000000 +0100
> @@ -51,6 +51,7 @@ enum {
> GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
> GCWQ_FREEZING = 1 << 3, /* freeze in progress */
> GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
> + GCWQ_PAUSING = 1 << 5,

Hmmm... confused. Pausing is per-wq, why is this flag on gcwq?
Shouldn't it be on workqueue_struct?

> +void pause_workqueue(struct workqueue_struct *wq)
> +{
> + unsigned int cpu;
> +
> + for_each_cwq_cpu(cpu, wq) {
> + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
> + struct global_cwq *gcwq = cwq->gcwq;
> +
> + spin_lock_irq(&gcwq->lock);
> +
> + WARN_ON(gcwq->flags & GCWQ_PAUSING);
> + gcwq->flags |= GCWQ_PAUSING;
> +
> + cwq->max_active = 0;
> +
> + spin_unlock_irq(&gcwq->lock);
> + }
> +
> + wait_event(wq->waitq, count_active(wq) == 0);
> +}
> +EXPORT_SYMBOL(pause_workqueue);

What if there are multiple callers of this function on the same wq?
Maybe something like wq->pause_depth and also use it from freeze path?

> +void resume_workqueue(struct workqueue_struct *wq)
> +{
> + unsigned int cpu;
> +
> + for_each_cwq_cpu(cpu, wq) {
> + struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
> + struct global_cwq *gcwq = cwq->gcwq;
> +
> + spin_lock_irq(&gcwq->lock);
> +
> + WARN_ON(!(gcwq->flags & GCWQ_PAUSING));
> + gcwq->flags &= ~GCWQ_PAUSING;
> +
> + cwq->max_active = wq->saved_max_active;
> +
> + wake_up_worker(gcwq);
> + spin_unlock_irq(&gcwq->lock);
> + }
> +}
> +EXPORT_SYMBOL(resume_workqueue);

I don't think wake_up_worker() would be sufficient.
cwq_activate_first_delayed() needs to be called to kick the delayed
work items.

I think it would be great if this can be abstracted out so that both
the freezer and explicit pausing use the same facility. They aren't
that different after all.

Thanks.

--
tejun


\
 
 \ /
  Last update: 2011-12-15 19:37    [W:0.068 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site