Here's yet another version of a patch to implement per-arch SD_*_INITs. 
This follows the same basic idea of my last patch, but

1) defines an arch-specific SD_NODE_INIT for the 4 NUMA arches (i386,
   x86_64, IA64 & PPC64),

2) defines *default* SD_CPU_INIT & SD_SIBLING_INIT for *all* arches,
   with the possibility of them being overridden by simply defining an
   arch-specific version in include/asm/topology.h.

The motivation behind the third version of this patch is that Martin feels
that there should be no "default" NUMA initializer because NUMA
characteristics are *very* arch/platform specific, and hence a "default"
NUMA initializer can only lead to confusion.  I agree with most of that,
but don't quite see as much harm in having a default as he does.
Nevertheless, to keep him quiet, I've run up this version of the patch. 
Martin, please run this through your magic test suite and make sure I
didn't break anything trivial.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>