net: slightly optimize eth_type_trans
commit45cf7959c30402d7c4ea43568a6f1bab0ba6ca63
authorLi RongQing <lirongqing@baidu.com>
Tue, 13 Nov 2018 01:34:31 +0000 (13 09:34 +0800)
committerDavid S. Miller <davem@davemloft.net>
Thu, 15 Nov 2018 23:10:59 +0000 (15 15:10 -0800)
tree0c8672578e4d0a9f5c60ad6310ccb55dc47f668f
parent982c17b9e3c27389a8d214333c686dab0e95cf63
net: slightly optimize eth_type_trans

netperf udp stream shows that eth_type_trans takes certain cpu,
so adjust the mac address check order, and firstly check if it
is device address, and only check if it is multicast address
only if not the device address.

After this change:
To unicast, and skb dst mac is device mac, this is most of time
reduce a comparision
To unicast, and skb dst mac is not device mac, nothing change
To multicast, increase a comparision

Before:
1.03%  [kernel]          [k] eth_type_trans

After:
0.78%  [kernel]          [k] eth_type_trans

Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ethernet/eth.c