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-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 2e1898e..2ddc43e 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 3318252..bfd654c 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,
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