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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2014-10-09 15:26:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-09 22:25:51 -0400
commit12220dea07f1ac6ac717707104773d771c3f3077 (patch)
tree5d12f754560c7b06e6d1bda9cf29000765fe921f
parent423c929cbbecc60e9c407f9048e58f5422f7995d (diff)
mm/slab: support slab merge
Slab merge is good feature to reduce fragmentation. If new creating slab have similar size and property with exsitent slab, this feature reuse it rather than creating new one. As a result, objects are packed into fewer slabs so that fragmentation is reduced. Below is result of my testing. * After boot, sleep 20; cat /proc/meminfo | grep Slab <Before> Slab: 25136 kB <After> Slab: 24364 kB We can save 3% memory used by slab. For supporting this feature in SLAB, we need to implement SLAB specific kmem_cache_flag() and __kmem_cache_alias(), because SLUB implements some SLUB specific processing related to debug flag and object size change on these functions. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slab.c26
-rw-r--r--mm/slab.h2
2 files changed, 27 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index f989af87b72c..328233a724af 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2104,6 +2104,32 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
return 0;
}
+unsigned long kmem_cache_flags(unsigned long object_size,
+ unsigned long flags, const char *name,
+ void (*ctor)(void *))
+{
+ return flags;
+}
+
+struct kmem_cache *
+__kmem_cache_alias(const char *name, size_t size, size_t align,
+ unsigned long flags, void (*ctor)(void *))
+{
+ struct kmem_cache *cachep;
+
+ cachep = find_mergeable(size, align, flags, name, ctor);
+ if (cachep) {
+ cachep->refcount++;
+
+ /*
+ * Adjust the object sizes so that we clear
+ * the complete object on kzalloc.
+ */
+ cachep->object_size = max_t(int, cachep->object_size, size);
+ }
+ return cachep;
+}
+
/**
* __kmem_cache_create - Create a cache.
* @cachep: cache management descriptor
diff --git a/mm/slab.h b/mm/slab.h
index c44d28b60609..50d29d716db4 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -92,7 +92,7 @@ struct mem_cgroup;
int slab_unmergeable(struct kmem_cache *s);
struct kmem_cache *find_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *));
-#ifdef CONFIG_SLUB
+#ifndef CONFIG_SLOB
struct kmem_cache *
__kmem_cache_alias(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *));