From 1f87e235e6fb92c2968b52b9191de04f1aff8e77 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 23 Nov 2008 23:24:32 -0800 Subject: eth: Declare an optimized compare_ether_addr_64bits() function Linus mentioned we could try to perform long word operations, even on potentially unaligned addresses, on x86 at least. David mentioned the HAVE_EFFICIENT_UNALIGNED_ACCESS test to handle this on all arches that have efficient unailgned accesses. I tried this idea and got nice assembly on 32 bits: 158: 33 82 38 01 00 00 xor 0x138(%edx),%eax 15e: 33 8a 34 01 00 00 xor 0x134(%edx),%ecx 164: c1 e0 10 shl $0x10,%eax 167: 09 c1 or %eax,%ecx 169: 74 0b je 176 And very nice assembly on 64 bits of course (one xor, one shl) Nice oprofile improvement in eth_type_trans(), 0.17 % instead of 0.41 %, expected since we remove 8 instructions on a fast path. This patch implements a compare_ether_addr_64bits() function, that uses the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ifdef to efficiently perform the 6 bytes comparison on all capable arches. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ethernet/eth.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/ethernet') diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index a87a171..280352a 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -165,8 +165,8 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) skb_pull(skb, ETH_HLEN); eth = eth_hdr(skb); - if (is_multicast_ether_addr(eth->h_dest)) { - if (!compare_ether_addr(eth->h_dest, dev->broadcast)) + if (unlikely(is_multicast_ether_addr(eth->h_dest))) { + if (!compare_ether_addr_64bits(eth->h_dest, dev->broadcast)) skb->pkt_type = PACKET_BROADCAST; else skb->pkt_type = PACKET_MULTICAST; @@ -181,7 +181,7 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) */ else if (1 /*dev->flags&IFF_PROMISC */ ) { - if (unlikely(compare_ether_addr(eth->h_dest, dev->dev_addr))) + if (unlikely(compare_ether_addr_64bits(eth->h_dest, dev->dev_addr))) skb->pkt_type = PACKET_OTHERHOST; } -- cgit v1.1