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| author | Jason Wang <jasowang@redhat.com> | 2011-06-10 00:56:17 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-06-11 15:57:47 -0700 |
| commit | 10a8d94a95742bb15b4e617ee9884bb4381362be (patch) | |
| tree | 768f2d92be0e12bca791bcb901ad4bdedc7d8a76 | |
| parent | 40d15cd06e87722b1cc27d56c8274617580f2c56 (diff) | |
| download | linux-10a8d94a95742bb15b4e617ee9884bb4381362be.tar.gz linux-10a8d94a95742bb15b4e617ee9884bb4381362be.tar.bz2 linux-10a8d94a95742bb15b4e617ee9884bb4381362be.zip | |
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 <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/macvtap.c | 2 | ||||
| -rw-r--r-- | drivers/net/tun.c | 2 | ||||
| -rw-r--r-- | drivers/net/virtio_net.c | 2 | ||||
| -rw-r--r-- | include/linux/virtio_net.h | 1 | ||||
| -rw-r--r-- | net/packet/af_packet.c | 2 |
5 files changed, 9 insertions, 0 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 6696e56e6320..ecee0fe65a97 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -508,6 +508,8 @@ static int macvtap_skb_to_vnet_hdr(const struct sk_buff *skb, vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM; vnet_hdr->csum_start = skb_checksum_start_offset(skb); vnet_hdr->csum_offset = skb->csum_offset; + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) { + vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID; } /* else everything is zero */ return 0; diff --git a/drivers/net/tun.c b/drivers/net/tun.c index ef68e13c042d..4dab85eecb60 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -788,6 +788,8 @@ static ssize_t tun_put_user(struct tun_struct *tun, gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM; gso.csum_start = skb_checksum_start_offset(skb); gso.csum_offset = skb->csum_offset; + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) { + gso.flags = VIRTIO_NET_HDR_F_DATA_VALID; } /* else everything is zero */ if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total, diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index f6853247a620..be3686a298da 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -274,6 +274,8 @@ static void receive_buf(struct net_device *dev, void *buf, unsigned int len) hdr->hdr.csum_start, hdr->hdr.csum_offset)) goto frame_err; + } else if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) { + skb->ip_summed = CHECKSUM_UNNECESSARY; } skb->protocol = eth_type_trans(skb, dev); diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index 136040bba3e3..970d5a2a9047 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -63,6 +63,7 @@ struct virtio_net_config { * specify GSO or CSUM features, you can simply ignore the header. */ struct virtio_net_hdr { #define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 // Use csum_start, csum_offset +#define VIRTIO_NET_HDR_F_DATA_VALID 2 // Csum is valid __u8 flags; #define VIRTIO_NET_HDR_GSO_NONE 0 // Not a GSO frame #define VIRTIO_NET_HDR_GSO_TCPV4 1 // GSO frame, IPv4 TCP (TSO) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 67f6749a0a45..b54ec41adea9 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1685,6 +1685,8 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock, vnet_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM; vnet_hdr.csum_start = skb_checksum_start_offset(skb); vnet_hdr.csum_offset = skb->csum_offset; + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) { + vnet_hdr.flags = VIRTIO_NET_HDR_F_DATA_VALID; } /* else everything is zero */ err = memcpy_toiovec(msg->msg_iov, (void *)&vnet_hdr, |