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Commit 63109846 authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds
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SLAB: don't allocate empty shared caches 



We can avoid allocating empty shared caches and avoid unecessary check of
cache->limit.  We save some memory.  We avoid bringing into CPU cache
unecessary cache lines.

All accesses to l3->shared are already checking NULL pointers so this patch is
safe.

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Acked-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 364fbb29

mm/slab.c

+15 −11
Original line number Diff line number Diff line
@@ -1223,19 +1223,20 @@ 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 *shared = NULL;

			struct array_cache **alien = NULL;



			nc = alloc_arraycache(node, cachep->limit,

						cachep->batchcount);

			if (!nc)

				goto bad;

			if (cachep->shared) {

				shared = alloc_arraycache(node,

					cachep->shared * cachep->batchcount,

					0xbaadf00d);

				if (!shared)

					goto bad;



			}

			if (use_alien_caches) {

                                alien = alloc_alien_cache(node, cachep->limit);

                                if (!alien)
@@ -1317,8 +1318,8 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb, 


			shared = l3->shared;

			if (shared) {

				free_block(cachep, l3->shared->entry,

					   l3->shared->avail, node);

				free_block(cachep, shared->entry,

					   shared->avail, node);

				l3->shared = NULL;

			}
@@ -3870,6 +3871,8 @@ static int alloc_kmemlist(struct kmem_cache *cachep) 
                                goto fail;

                }



		new_shared = NULL;

		if (cachep->shared) {

			new_shared = alloc_arraycache(node,

				cachep->shared*cachep->batchcount,

					0xbaadf00d);
@@ -3877,6 +3880,7 @@ static int alloc_kmemlist(struct kmem_cache *cachep) 
				free_alien_cache(new_alien);

				goto fail;

			}

		}



		l3 = cachep->nodelists[node];

		if (l3) {