Enable system hashtable memory to be distributed among nodes on x86_64 NUMA
Forcing the kernel to use node interleaved vmalloc instead of bootmem
for the system hashtable memory (alloc_large_system_hash) reduces the
memory imbalance on node 0 by around 40MB on a 8 node x86_64 NUMA box:
Before the following patch, on bootup of a 8 node box:
Node 0 MemTotal: 3407488 kB
Node 0 MemFree: 3206296 kB
Node 0 MemUsed: 201192 kB
Node 0 Active: 7012 kB
Node 0 Inactive: 512 kB
Node 0 Dirty: 0 kB
Node 0 Writeback: 0 kB
Node 0 FilePages: 1912 kB
Node 0 Mapped: 420 kB
Node 0 AnonPages: 5612 kB
Node 0 PageTables: 468 kB
Node 0 NFS_Unstable: 0 kB
Node 0 Bounce: 0 kB
Node 0 Slab: 5408 kB
Node 0 SReclaimable: 644 kB
Node 0 SUnreclaim: 4764 kB
After the patch (or using hashdist=1 on the kernel command line):
Node 0 MemTotal: 3407488 kB
Node 0 MemFree: 3247608 kB
Node 0 MemUsed: 159880 kB
Node 0 Active: 3012 kB
Node 0 Inactive: 616 kB
Node 0 Dirty: 0 kB
Node 0 Writeback: 0 kB
Node 0 FilePages: 2424 kB
Node 0 Mapped: 380 kB
Node 0 AnonPages: 1200 kB
Node 0 PageTables: 396 kB
Node 0 NFS_Unstable: 0 kB
Node 0 Bounce: 0 kB
Node 0 Slab: 6304 kB
Node 0 SReclaimable: 1596 kB
Node 0 SUnreclaim: 4708 kB
I guess it is a good idea to keep HASHDIST_DEFAULT "on" for x86_64 NUMA since
x86_64 has no dearth of vmalloc space? Or maybe enable hash distribution for
all 64bit NUMA arches? The following patch does it only for x86_64.
Signed-off-by: Pravin B. Shelar <[email protected]>
Signed-off-by: Ravikiran Thirumalai <[email protected]>
Signed-off-by: Shai Fultheim <[email protected]>
Index: linux-2.6.20-rc1/include/linux/bootmem.h
===================================================================
--- linux-2.6.20-rc1.orig/include/linux/bootmem.h 2006-12-21 14:34:36.321610875 -0800
+++ linux-2.6.20-rc1/include/linux/bootmem.h 2006-12-26 15:55:04.501064560 -0800
@@ -122,9 +122,9 @@ extern void *alloc_large_system_hash(con
#define HASH_EARLY 0x00000001 /* Allocating during early boot? */
/* Only NUMA needs hash distribution.
- * IA64 is known to have sufficient vmalloc space.
+ * IA64 and x86_64 have sufficient vmalloc space.
*/
-#if defined(CONFIG_NUMA) && defined(CONFIG_IA64)
+#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64))
#define HASHDIST_DEFAULT 1
#else
#define HASHDIST_DEFAULT 0
-
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