From: Stephen Hemminger Date: Thu, 10 Apr 2008 11:00:28 +0000 (-0700) Subject: IPV4: use xor rather than multiple ands for route compare X-Git-Tag: v2.6.26-rc1~1138^2~131 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c0b8c32b1c96afc9b32b717927330025cc1c501e;p=linux-2.6 IPV4: use xor rather than multiple ands for route compare 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 Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/net/ipv4/route.c b/net/ipv4/route.c index a1c5b8dbdf..139799f8a8 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -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);