Re: [PATCH -mm 2/3] Freezer: Use wait queue instead of busy looping (updated)

[Oleg Nesterov <oleg@tv-sign.ru>]

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().

Oleg.

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