mm/slab: support slab merge (12220dea) · Commits · 戴 / test

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>

mm/slab.c

+26 −0

Original line number	Diff line number	Diff line
		@@ -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

mm/slab.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 ));

Admin message