linux-kernel - [patch 2/2] slab, x86_64: skip cache_free

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Date:	Mon, 9 Apr 2007 11:07:44 -0700
From:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
To:	akpm@...ux-foundation.org
Cc:	christoph@...eter.com, Andi Kleen <andi@...stfloor.org>,
	Eric Dumazet <dada1@...mosbay.com>,
	linux kernel <linux-kernel@...r.kernel.org>,
	suresh.b.siddha@...el.com
Subject: [patch 2/2] slab, x86_64: skip cache_free_alien() on non NUMA

set use_alien_caches to 0 on non NUMA platforms. And avoid calling
the cache_free_alien() when use_alien_caches is not set. This will avoid
the cache miss that happens while dereferencing slabp to get nodeid.

Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---

diff --git a/mm/slab.c b/mm/slab.c
index 8fdaffa..146082d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1146,7 +1146,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 	 * Make sure we are not freeing a object from another node to the array
 	 * cache on this cpu.
 	 */
-	if (likely(slabp->nodeid == node) || unlikely(!use_alien_caches))
+	if (likely(slabp->nodeid == node))
 		return 0;
 
 	l3 = cachep->nodelists[node];
@@ -1394,6 +1394,9 @@ void __init kmem_cache_init(void)
 	int order;
 	int node;
 
+	if (num_possible_nodes() == 1)
+		use_alien_caches = 0;
+
 	for (i = 0; i < NUM_INIT_LISTS; i++) {
 		kmem_list3_init(&initkmem_list3[i]);
 		if (i < MAX_NUMNODES)
@@ -3563,7 +3566,7 @@ 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))
+	if (use_alien_caches && cache_free_alien(cachep, objp))
 		return;
 
 	if (likely(ac->avail < ac->limit)) {
-
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