From: "Michael S. Tsirkin" <mst@xxxxxxxxxx> Date: Fri, 10 Jun 2011 14:28:28 +0300 > On Fri, Jun 10, 2011 at 06:56:17PM +0800, Jason Wang wrote: >> 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. > > This wasn't required by the spec, but maybe it should be. > >> 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 <jasowang@xxxxxxxxxx> > > > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Applied to net-next-2.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
