[PATCH] Conntrack Hash Allocation using __get_free_pages

Here is a patch that just makes it use get_free_pages to test the TLB
theory.  Another obvious improvement would be to not use list_heads for
the hash table buckets - a single pointer would likely suffice and it
would cut the hash table in half, saving cache, TLB and memory.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

net/ipv4/netfilter/ip_conntrack_core.c

@@ -75,6 +75,7 @@ static kmem_cache_t *ip_conntrack_expect_cachep;
 struct ip_conntrack ip_conntrack_untracked;
 unsigned int ip_ct_log_invalid;
 static LIST_HEAD(unconfirmed);
+static int ip_conntrack_vmalloc;
 
 DEFINE_PER_CPU(struct ip_conntrack_stat, ip_conntrack_stat);
 
@@ -1309,6 +1310,16 @@ static int kill_all(struct ip_conntrack *i, void *data)
 	return 1;
 }
 
+static void free_conntrack_hash(void)
+{
+	if (ip_conntrack_vmalloc)
+		vfree(ip_conntrack_hash);
+	else
+		free_pages((unsigned long)ip_conntrack_hash, 
+			   get_order(sizeof(struct list_head)
+				     * ip_conntrack_htable_size));
+}
+
 /* Mishearing the voices in his head, our hero wonders how he's
    supposed to kill the mall. */
 void ip_conntrack_cleanup(void)
@@ -1328,7 +1339,7 @@ void ip_conntrack_cleanup(void)
 
 	kmem_cache_destroy(ip_conntrack_cachep);
 	kmem_cache_destroy(ip_conntrack_expect_cachep);
-	vfree(ip_conntrack_hash);
+	free_conntrack_hash();
 	nf_unregister_sockopt(&so_getorigdst);
 }
 
@@ -1366,8 +1377,20 @@ int __init ip_conntrack_init(void)
 		return ret;
 	}
 
-	ip_conntrack_hash = vmalloc(sizeof(struct list_head)
-				    * ip_conntrack_htable_size);
+	/* AK: the hash table is twice as big than needed because it
+	   uses list_head.  it would be much nicer to caches to use a
+	   single pointer list head here. */
+	ip_conntrack_vmalloc = 0; 
+	ip_conntrack_hash 
+		=(void*)__get_free_pages(GFP_KERNEL, 
+					 get_order(sizeof(struct list_head)
+						   *ip_conntrack_htable_size));
+	if (!ip_conntrack_hash) { 
+		ip_conntrack_vmalloc = 1;
+		printk(KERN_WARNING "ip_conntrack: falling back to vmalloc.\n");
+		ip_conntrack_hash = vmalloc(sizeof(struct list_head)
+					    * ip_conntrack_htable_size);
+	}
 	if (!ip_conntrack_hash) {
 		printk(KERN_ERR "Unable to create ip_conntrack_hash\n");
 		goto err_unreg_sockopt;
@@ -1375,7 +1398,7 @@ int __init ip_conntrack_init(void)
 
 	ip_conntrack_cachep = kmem_cache_create("ip_conntrack",
 	                                        sizeof(struct ip_conntrack), 0,
-	                                        SLAB_HWCACHE_ALIGN, NULL, NULL);
+	                                        SLAB_HWCACHE_ALIGN, NULL,NULL);
 	if (!ip_conntrack_cachep) {
 		printk(KERN_ERR "Unable to create ip_conntrack slab cache\n");
 		goto err_free_hash;
@@ -1416,7 +1439,7 @@ int __init ip_conntrack_init(void)
 err_free_conntrack_slab:
 	kmem_cache_destroy(ip_conntrack_cachep);
 err_free_hash:
-	vfree(ip_conntrack_hash);
+	free_conntrack_hash();
 err_unreg_sockopt:
 	nf_unregister_sockopt(&so_getorigdst);