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authorAnton Blanchard <anton@samba.org>2009-03-31 15:23:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-01 08:59:14 -0700
commitc2fdf3a9b2d52842808a8e551b53b55dd9b45030 (patch)
tree71affdf51cbf97147ebf3bf41814027c7b63b72a
parent704503d836042d4a4c7685b7036e7de0418fbc0f (diff)
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>
-rw-r--r--include/linux/bootmem.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index 455d83219fa..bc3ab707369 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -146,10 +146,10 @@ extern void *alloc_large_system_hash(const char *tablename,
#define HASH_EARLY 0x00000001 /* Allocating during early boot? */
-/* Only NUMA needs hash distribution.
- * IA64 and x86_64 have sufficient vmalloc space.
+/* Only NUMA needs hash distribution. 64bit NUMA architectures have
+ * sufficient vmalloc space.
*/
-#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64))
+#if defined(CONFIG_NUMA) && defined(CONFIG_64BIT)
#define HASHDIST_DEFAULT 1
#else
#define HASHDIST_DEFAULT 0