CONFIG_NR_CPUS

[Josh Boyer]

On Mon, May 21, 2012 at 08:42:12AM -0400, Prarit Bhargava wrote:
> Josh, the reality is that 64 isn't "enough" anymore.  Even deskside systems are
> starting to ship with 32 cores, so increasing the number of CPUs to 128 is a
> good idea.  I've had a lot of experience with larger systems.  The increase in
> memory footprint is minimal (a few Kb, not Mb).

I'll get this into rawhide shortly unless someone else brings up
counter-points (doubtful).

> Jumping to 128 is a very good idea.  We know it is stable given RHEL's support
> of 4096 (again, I don't think Fedora should entertain jumping to 4096 for a
> variety of reasons).

I'm not concerned with the stability aspect of it.  Before the
recent-ish change, we had it set to 256 on released kernels and 512 for
rawhide/debug kernels.  We know it works.  For rawhide/debug kernels we
already set it to MAXSMP.

For the record, I'm not going to change 32-bit kernels.  I don't see
much of a need to increase that beyond what it is today and the same
arguments about more cores being added don't really apply to 32-bit
chips.

(Before someone points out that you can run 32-bit kernels on 64-bit
hardware, I just wanted to say I don't care.  If you have a CPU that has
128 cores and want to use them all, use a 64-bit kernel ;) .)

josh