From: Jason Wang Date: Fri, 10 Jun 2011 00:56:17 +0000 (+0000) Subject: virtio_net: introduce VIRTIO_NET_HDR_F_DATA_VALID X-Git-Tag: v3.1-rc1~316^2~450^2~9 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=10a8d94a95742bb15b4e617ee9884bb4381362be;p=pandora-kernel.git virtio_net: introduce VIRTIO_NET_HDR_F_DATA_VALID There's no need for the guest to validate the checksum if it have been validated by host nics. So this patch introduces a new flag - VIRTIO_NET_HDR_F_DATA_VALID which is used to bypass the checksum examing in guest. The backend (tap/macvtap) may set this flag when met skbs with CHECKSUM_UNNECESSARY to save cpu utilization. No feature negotiation is needed as old driver just ignore this flag. Iperf shows 12%-30% performance improvement for UDP traffic. For TCP, when gro is on no difference as it produces skb with partial checksum. But when gro is disabled, 20% or even higher improvement could be measured by netperf. Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- Reading git-diff-tree failed