Re: [PATCH] x86_64: resize NR_IRQS for large machines

From: Alan Mayer
Date: Wed Mar 26 2008 - 14:49:22 EST



On Wed, 26 Mar 2008, Pavel Machek wrote:

> Hi!
>
> > Subject: [PATCH] x86_64: resize NR_IRQS for large machines
> >
> > From: Alan Mayer <ajm@xxxxxxx>
> >
> > On machines with very large numbers of cpus, tables that are dimensioned
> > by NR_IRQS get very large, especially the irq_desc table. They are also
> > very sparsely used. When the cpu count is > MAX_IO_APICS, use MAX_IO_APICS
> > to set NR_IRQS, otherwise use NR_CPUS.
> >
> > Signed-off-by: Alan Mayer <ajm@xxxxxxx>
> >
> > Reviewed-by: Christoph Lameter <clameter@xxxxxxx>
>
> > ===================================================================
> > --- v2.6.25-rc6.orig/include/asm-x86/irq_64.h 2008-03-19 16:52:52.000000000 -0500
> > +++ v2.6.25-rc6/include/asm-x86/irq_64.h 2008-03-20 16:46:51.000000000 -0500
> > @@ -10,6 +10,10 @@
> > * <tomsoft@xxxxxxxxxxxxxxxxxxxxxxxxx>
> > */
> >
> > +#if !defined(MAX_IO_APICS)
> > +#include <asm/apicdef.h>
> > +#endif
> > +
>
> This is very ugly. Why not include it unconditionally -- with guard in
> apicdef.h?
> Pavel

Okay, I can change that.

--ajm

> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
>

--
Alan J. Mayer
SGI
ajm@xxxxxxx
WORK: 651-683-3131
HOME: 651-407-0134
--

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