From: Andi Kleen <ak@suse.de>
To: Daniel Walker <dwalker@mvista.com>
Subject: Re: + i386-time-avoid-pit-smp-lockups.patch added to -mm tree
Date: Thu, 19 Oct 2006 15:47:09 +0200
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Cc: linux-kernel@vger.kernel.org, johnstul@us.ibm.com, mingo@elte.hu,
       tglx@linutronix.de
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On Thursday 19 October 2006 15:44, Daniel Walker wrote:
> On Wed, 2006-10-11 at 14:26 -0700, akpm@osdl.org 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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