Re: [v2 PATCH 1/4] timers: framework to identify pinned timers.

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* Oleg Nesterov <oleg@xxxxxxxxxx> [2009-03-05 17:53:40]:

> On 03/04, Arun R Bharadwaj wrote:
> >
> > +static inline unsigned long tbase_get_flag_bits(struct timer_list *timer)
> > +{
> > +	return tbase_get_deferrable(timer->base) |
> > +				tbase_get_pinned(timer->base);
> > +}
> 
> I'd say this looks a bit strange. Hopefully compiler can optimize this code
> to return (unsigned long)base & (TBASE_DEFERRABLE_FLAG | TBASE_PINNED_FLAG).
>

Yes, it does.

> > @@ -736,6 +759,7 @@ void add_timer_on(struct timer_list *tim
> >  	struct tvec_base *base = per_cpu(tvec_bases, cpu);
> >  	unsigned long flags;
> >
> > +	timer_set_pinned(timer);
> 
> But we never clear TBASE_PINNED_FLAG?
> 
> If we use mod_timer() next time, the timer remains "pinned". I do not say
> this is really wrong, but a bit strange imho.
> 
> Oleg.
>

The pinned timer would expect to continue firing on the same CPU
although it does a mod_timer() the next time, right?
Thats why I have not cleared the TBASE_PINNED_FLAG.

--arun
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