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ipv4: save cpu cycles from check_leaf()

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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-07-18 03:16:33 +00:00 committed by David S. Miller
parent d3aaeb38c4
commit 5c74501f76
1 changed files with 6 additions and 6 deletions
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12
net/ipv4/fib_trie.c
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@ -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;
}
}