On 08/02, Rafael J. Wysocki wrote:
>
> On Thursday, 2 August 2007 23:23, Oleg Nesterov wrote:
> > On 08/02, Rafael J. Wysocki wrote:
> > >
> > > On Thursday, 2 August 2007 20:40, Oleg Nesterov wrote:
> > > > On 08/02, Rafael J. Wysocki wrote:
> > > > >
> > > > > @@ -171,6 +186,10 @@ static int try_to_freeze_tasks(int freez
> > > > >
> > > > > end_time = jiffies + TIMEOUT;
> > > > > do {
> > > > > + DEFINE_WAIT(wait);
> > > > > +
> > > > > + add_wait_queue(&refrigerator_waitq, &wait);
> > > >
> > > > Hmm. In that case I'd sugest to use prepare_to_wait(). This means that
> > > > multiple wakeups from refrigerator() won't do unnecessary work,
> > >
> > > I'm not sure what you mean.
> > >
> > > Do you mean that if we are TASK_UNINTERRUPTIBLE, then the first wake up
> > > should remove us from the queue?
> >
> > No, not because we are TASK_UNINTERRUPTIBLE, but yes, first wake up will
> > remove us because DEFINE_WAIT() uses autoremove_wake_function().
>
> Yes, it does, but the prepare_to_wait() version would only cause current to
> become TASK_UNINTERRUPTIBLE before it sends freezing requests, the other
> differences don't seem to matter. I'm trying to understand why it would change
> the behavior in the way you have described.
Ugh, this is not the first time when I didn't read your patch carefully, sorry!
I missed that your patch already uses DEFINE_WAIT(), and I was confused by the
add_wait_queue() which is usually used along with DECLARE_WAITQUEUE().
Oleg.
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