Bug#491309: NR_CPUS in debian linux-images

[Mike Travis <travis@sgi.com>]

Bastian Blank wrote:
> On Tue, Jul 29, 2008 at 07:48:11AM -0700, Mike Travis wrote:
>> You could look at the 2.6.27 version of include/asm-x86/irq_vectors.h to see
>> how NR_IRQ's is somewhat lessened (at least from a NR_CPUS=4096 perspective.)
> 
> May this change be applicable to 2.6.26 or will it break something else?
> 
> Bastian
> 

I believe it is ok.  The number of irq's is not really based on NR_CPUS but
the number of IO_APICS.  But I can't say for sure as I've been solely focused
on 2.6.27 and haven't been following the breakup of NR_IRQS, NR_IRQ_VECTORS
and NR_VECTORS and how they are used in various places.

Btw, the biggest problem I found with increasing NR_CPUS was overflowing the
stack, though I doubt increasing to 96 or 128 will trigger any of the hot spots
fixed in 2.6.27.

Thanks,
Mike