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Commit 1807a1aa authored by Siddha, Suresh B's avatar Siddha, Suresh B Committed by Linus Torvalds
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slab: skip calling cache_free_alien() when the platform is not numa capable 



Skip calling cache_free_alien() when the platform is not numa capable.
This will avoid cache misses that happen while accessing slabp (which is
per page memory reference) to get nodeid.  Instead use a global variable to
skip the call, which is mostly likely to be present in the cache.

This gives a 0.8% performance boost with the database oltp workload on a
quad-core SMP platform and by any means the number is not small :)

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 32d21985

mm/slab.c

+12 −2
Original line number Diff line number Diff line
@@ -883,6 +883,7 @@ static void __slab_error(const char *function, struct kmem_cache *cachep, 
  */



static int use_alien_caches __read_mostly = 1;

static int numa_platform __read_mostly = 1;

static int __init noaliencache_setup(char *s)

{

	use_alien_caches = 0;
@@ -1399,8 +1400,10 @@ void __init kmem_cache_init(void) 
	int order;

	int node;



	if (num_possible_nodes() == 1)

	if (num_possible_nodes() == 1) {

		use_alien_caches = 0;

		numa_platform = 0;

	}



	for (i = 0; i < NUM_INIT_LISTS; i++) {

		kmem_list3_init(&initkmem_list3[i]);
@@ -3558,7 +3561,14 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp) 
	check_irq_off();

	objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));



	if (cache_free_alien(cachep, objp))

	/*

	 * Skip calling cache_free_alien() when the platform is not numa.

	 * This will avoid cache misses that happen while accessing slabp (which

	 * is per page memory  reference) to get nodeid. Instead use a global

	 * variable to skip the call, which is mostly likely to be present in

	 * the cache.

	 */

	if (numa_platform && cache_free_alien(cachep, objp))

		return;



	if (likely(ac->avail < ac->limit)) {