tree 71affdf51cbf97147ebf3bf41814027c7b63b72a
parent 704503d836042d4a4c7685b7036e7de0418fbc0f
author Anton Blanchard <anton@samba.org> 1238538199 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1238601554 -0700

mm: enable hashdist by default on 64bit NUMA

On PowerPC we allocate large boot time hashes on node 0.  This leads to an
imbalance in the free memory, for example on a 64GB box (4 x 16GB nodes):

Free memory:
Node 0: 97.03%
Node 1: 98.54%
Node 2: 98.42%
Node 3: 98.53%

If we switch to using vmalloc (like ia64 and x86-64) things are more
balanced:

Free memory:
Node 0: 97.53%
Node 1: 98.35%
Node 2: 98.33%
Node 3: 98.33%

For many HPC applications we are limited by the free available memory on
the smallest node, so even though the same amount of memory is used the
better balancing helps.

Since all 64bit NUMA capable architectures should have sufficient vmalloc
space, it makes sense to enable it via CONFIG_64BIT.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>