diff options
| author | Eric Dumazet <dada1@cosmosbay.com> | 2008-11-23 23:24:32 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-11-23 23:24:32 -0800 |
| commit | 1f87e235e6fb92c2968b52b9191de04f1aff8e77 (patch) | |
| tree | ab774d239c61b6c206ef07398828533cdd01915e /net/ethernet | |
| parent | 70eb1bfd52e97120eddf9b5aaabfe1ecdf4eb663 (diff) | |
| download | linux-1f87e235e6fb92c2968b52b9191de04f1aff8e77.tar.bz2 | |
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 <eth_type_trans+0x87>
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 <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ethernet')
| -rw-r--r-- | net/ethernet/eth.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index a87a171d9914..280352aba403 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; } |