2.6.27 saw the relevant fixes for NR_CPUS > 128 by the sgi guys:
"Yes, we are aiming at having NR_CPUS=4096 as the default for distros
using 2.6.27." Mike Travis <travis@sgi.com>
don't shoot that high but 32 is much too low, 512 is seen in fedora,
thus presumed good.
svn path=/dists/trunk/linux-2.6/; revision=12823
sparsemem is the only left 64-bit mem model:
"DISCONTIGMEM has a higher overhead than sparsemem
FLATMEMs benefits are minimal."
see b263295dbffd33b0fbff670720fa178c30e3392a
svn path=/dists/trunk/linux-2.6/; revision=10296