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Commit 5c74501f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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ipv4: save cpu cycles from check_leaf() 



Compiler is not smart enough to avoid double BSWAP instructions in
ntohl(inet_make_mask(plen)).

Lets cache this value in struct leaf_info, (fill a hole on 64bit arches)

With route cache disabled, this saves ~2% of cpu in udpflood bench on
x86_64 machine.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d3aaeb38

net/ipv4/fib_trie.c

+6 −6
Original line number Diff line number Diff line
@@ -110,9 +110,10 @@ struct leaf { 


struct leaf_info {

	struct hlist_node hlist;

	struct rcu_head rcu;

	int plen;

	u32 mask_plen; /* ntohl(inet_make_mask(plen)) */

	struct list_head falh;

	struct rcu_head rcu;

};



struct tnode {
@@ -451,6 +452,7 @@ static struct leaf_info *leaf_info_new(int plen) 
	struct leaf_info *li = kmalloc(sizeof(struct leaf_info),  GFP_KERNEL);

	if (li) {

		li->plen = plen;

		li->mask_plen = ntohl(inet_make_mask(plen));

		INIT_LIST_HEAD(&li->falh);

	}

	return li;
@@ -1359,10 +1361,8 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l, 


	hlist_for_each_entry_rcu(li, node, hhead, hlist) {

		struct fib_alias *fa;

		int plen = li->plen;

		__be32 mask = inet_make_mask(plen);



		if (l->key != (key & ntohl(mask)))

		if (l->key != (key & li->mask_plen))

			continue;



		list_for_each_entry_rcu(fa, &li->falh, fa_list) {
@@ -1394,7 +1394,7 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l, 
#ifdef CONFIG_IP_FIB_TRIE_STATS

				t->stats.semantic_match_passed++;

#endif

				res->prefixlen = plen;

				res->prefixlen = li->plen;

				res->nh_sel = nhsel;

				res->type = fa->fa_type;

				res->scope = fa->fa_info->fib_scope;
@@ -1402,7 +1402,7 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l, 
				res->table = tb;

				res->fa_head = &li->falh;

				if (!(fib_flags & FIB_LOOKUP_NOREF))

					atomic_inc(&res->fi->fib_clntref);

					atomic_inc(&fi->fib_clntref);

				return 0;

			}

		}