From 12220dea07f1ac6ac717707104773d771c3f3077 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 9 Oct 2014 15:26:24 -0700 Subject: 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 Slab: 25136 kB 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 Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'mm/slab.c') 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 -- cgit v1.2.3-55-g7522