Subject: Re: [PATCH 3/6] [IPV4] trie: put leaf nodes in a slab cache

From: Eric Dumazet <[email-masked]>
Date: Tue, 15 Jan 2008 07:49:39 +0100

Stephen Hemminger a écrit :
> This improves locality for operations that touch all the leaves.
> Later patch will grow the size of the leaf so it becomes more
> important.
> 
> Signed-off-by: Stephen Hemminger <[email-masked]>
> 
> 
> --- a/net/ipv4/fib_trie.c	2008-01-14 12:26:51.000000000 -0800
> +++ b/net/ipv4/fib_trie.c	2008-01-14 13:41:00.000000000 -0800
> @@ -162,6 +162,7 @@ static struct tnode *halve(struct trie *
>  static void tnode_free(struct tnode *tn);
>  
>  static struct kmem_cache *fn_alias_kmem __read_mostly;
> +static struct kmem_cache *trie_leaf_kmem __read_mostly;
>  
>  static inline struct tnode *node_parent(struct node *node)
>  {
> @@ -316,7 +317,8 @@ static inline void alias_free_mem_rcu(st
>  
>  static void __leaf_free_rcu(struct rcu_head *head)
>  {
> -	kfree(container_of(head, struct leaf, rcu));
> +	struct leaf *leaf = container_of(head, struct leaf, rcu);
> +	kmem_cache_free(trie_leaf_kmem, leaf);
>  }
>  
>  static void __leaf_info_free_rcu(struct rcu_head *head)
> @@ -366,7 +368,7 @@ static inline void tnode_free(struct tno
>  
>  static struct leaf *leaf_new(void)
>  {
> -	struct leaf *l = kmalloc(sizeof(struct leaf),  GFP_KERNEL);
> +	struct leaf *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
>  	if (l) {
>  		l->parent = T_LEAF;
>  		INIT_HLIST_HEAD(&l->list);
> @@ -1927,6 +1929,9 @@ void __init fib_hash_init(void)
>  {
>  	fn_alias_kmem = kmem_cache_create("ip_fib_alias", sizeof(struct fib_alias),
>  					  0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> +
> +	trie_leaf_kmem = kmem_cache_create("ip_fib_trie", sizeof(struct leaf),
> +					   0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
>  }
>  

Do we really need HWCACHE_ALIGN ? so many wasted space ...