Re: + i386-time-avoid-pit-smp-lockups.patch added to -mm tree

From: Andi Kleen
Date: Thu Oct 19 2006 - 09:47:42 EST


On Thursday 19 October 2006 15:44, Daniel Walker wrote:
> On Wed, 2006-10-11 at 14:26 -0700, akpm@xxxxxxxx wrote:
>
> > diff -puN arch/i386/kernel/i8253.c~i386-time-avoid-pit-smp-lockups arch/i386/kernel/i8253.c
> > --- a/arch/i386/kernel/i8253.c~i386-time-avoid-pit-smp-lockups
> > +++ a/arch/i386/kernel/i8253.c
> > @@ -109,7 +109,7 @@ static struct clocksource clocksource_pi
> >
> > static int __init init_pit_clocksource(void)
> > {
> > - if (num_possible_cpus() > 4) /* PIT does not scale! */
> > + if (num_possible_cpus() > 1) /* PIT does not scale! */
> > return 0;
> >
>
> Can we ifdef some code here on CONFIG_SMP . It bugs me that there just
> dead code laying around on smp systems.

The optimizer should optimize it all out since num_possible_cpus() is a 0
constant on UP.

-Andi
-
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