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IPV4: use xor rather than multiple ands for route compare

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The comparison in ip_route_input is a hot path, by recoding the C
"and" as bit operations, fewer conditional branches get generated
so the code should be faster. Maybe someday Gcc will be smart
enough to do this?

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2008-04-10 04:00:28 -07:00 committed by David S. Miller
parent 996b1dbadc
commit c0b8c32b1c
1 changed files with 5 additions and 5 deletions
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10
net/ipv4/route.c
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@ -2077,12 +2077,12 @@ int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr,
rcu_read_lock();
for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
rth = rcu_dereference(rth->u.dst.rt_next)) {
if (rth->fl.fl4_dst == daddr &&
rth->fl.fl4_src == saddr &&
rth->fl.iif == iif &&
rth->fl.oif == 0 &&
if (((rth->fl.fl4_dst ^ daddr) |
(rth->fl.fl4_src ^ saddr) |
(rth->fl.iif ^ iif) |
rth->fl.oif |
(rth->fl.fl4_tos ^ tos)) == 0 &&
rth->fl.mark == skb->mark &&
rth->fl.fl4_tos == tos &&
net_eq(dev_net(rth->u.dst.dev), net) &&
rth->rt_genid == atomic_read(&rt_genid)) {
dst_use(&rth->u.dst, jiffies);