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authorPaul Menage <menage@google.com>2006-12-06 20:32:16 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:21 -0800
commit3395ee0588795b0b3bd889c260e55959cf2b61f5 (patch)
treeea2513a28464a5b2907a9cb71cbfb6be88389205
parent8f5be20bf87da7c7c59c5cc84f630a1eca5cc99c (diff)
downloadlinux-2.6.34-ux500-3395ee0588795b0b3bd889c260e55959cf2b61f5.tar.gz
[PATCH] mm: add noaliencache boot option to disable numa alien caches
When using numa=fake on non-NUMA hardware there is no benefit to having the alien caches, and they consume much memory. Add a kernel boot option to disable them. Christoph sayeth "This is good to have even on large NUMA. The problem is that the alien caches grow by the square of the size of the system in terms of nodes." Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--Documentation/kernel-parameters.txt4
-rw-r--r--mm/slab.c38
2 files changed, 33 insertions, 9 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2e1898e4e8f..2ddc43ef4de 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1012,6 +1012,10 @@ and is between 256 and 4096 characters. It is defined in the file
emulation library even if a 387 maths coprocessor
is present.
+ noaliencache [MM, NUMA] Disables the allcoation of alien caches in
+ the slab allocator. Saves per-node memory, but will
+ impact performance on real NUMA hardware.
+
noalign [KNL,ARM]
noapic [SMP,APIC] Tells the kernel to not make use of any
diff --git a/mm/slab.c b/mm/slab.c
index 3318252f657..bfd654c0ef4 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -869,6 +869,22 @@ static void __slab_error(const char *function, struct kmem_cache *cachep,
dump_stack();
}
+/*
+ * By default on NUMA we use alien caches to stage the freeing of
+ * objects allocated from other nodes. This causes massive memory
+ * inefficiencies when using fake NUMA setup to split memory into a
+ * large number of small nodes, so it can be disabled on the command
+ * line
+ */
+
+static int use_alien_caches __read_mostly = 1;
+static int __init noaliencache_setup(char *s)
+{
+ use_alien_caches = 0;
+ return 1;
+}
+__setup("noaliencache", noaliencache_setup);
+
#ifdef CONFIG_NUMA
/*
* Special reaping functions for NUMA systems called from cache_reap().
@@ -1117,7 +1133,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
* Make sure we are not freeing a object from another node to the array
* cache on this cpu.
*/
- if (likely(slabp->nodeid == node))
+ if (likely(slabp->nodeid == node) || unlikely(!use_alien_caches))
return 0;
l3 = cachep->nodelists[node];
@@ -1195,7 +1211,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
list_for_each_entry(cachep, &cache_chain, next) {
struct array_cache *nc;
struct array_cache *shared;
- struct array_cache **alien;
+ struct array_cache **alien = NULL;
nc = alloc_arraycache(node, cachep->limit,
cachep->batchcount);
@@ -1207,9 +1223,11 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
if (!shared)
goto bad;
- alien = alloc_alien_cache(node, cachep->limit);
- if (!alien)
- goto bad;
+ if (use_alien_caches) {
+ alien = alloc_alien_cache(node, cachep->limit);
+ if (!alien)
+ goto bad;
+ }
cachep->array[cpu] = nc;
l3 = cachep->nodelists[node];
BUG_ON(!l3);
@@ -3590,13 +3608,15 @@ static int alloc_kmemlist(struct kmem_cache *cachep)
int node;
struct kmem_list3 *l3;
struct array_cache *new_shared;
- struct array_cache **new_alien;
+ struct array_cache **new_alien = NULL;
for_each_online_node(node) {
- new_alien = alloc_alien_cache(node, cachep->limit);
- if (!new_alien)
- goto fail;
+ if (use_alien_caches) {
+ new_alien = alloc_alien_cache(node, cachep->limit);
+ if (!new_alien)
+ goto fail;
+ }
new_shared = alloc_arraycache(node,
cachep->shared*cachep->batchcount,