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lguest: Use GSO/IFF_VNET_HDR extensions on tun/tap 

Guest -> Host 1GB TCP:
Before 20.1974 seconds xmit 214510 recv 5 timeout 214491 usec 278
After 8.43625 seconds xmit 95640 recv 198266 timeout 49771 usec 1252

Host -> Guest 1GB TCP:
Before: Seconds 9.98854 xmit 172166 recv 5344 timeout 172157 usec 251
After: Seconds 5.72803 xmit 244322 recv 9919 timeout 244302 usec 156

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2008-07-29 09:58:37 -05:00
parent 9254926f85
commit 398f187d74
1 changed files with 20 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
Documentation/lguest/lguest.c
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@ -929,11 +929,9 @@ static void handle_net_output(int fd, struct virtqueue *vq, bool timeout)
while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) {
if (in)
errx(1, "Input buffers in output queue?");
/* Check header, but otherwise ignore it (we told the Guest we
* supported no features, so it shouldn't have anything
* interesting). */
(void)convert(&iov[0], struct virtio_net_hdr);
len = writev(vq->dev->fd, iov+1, out-1);
len = writev(vq->dev->fd, iov, out);
if (len < 0)
err(1, "Writing network packet to tun");
add_used_and_trigger(fd, vq, head, len);
num++;
}
@ -958,7 +956,6 @@ static bool handle_tun_input(int fd, struct device *dev)
unsigned int head, in_num, out_num;
int len;
struct iovec iov[dev->vq->vring.num];
struct virtio_net_hdr *hdr;
/* First we need a network buffer from the Guests's recv virtqueue. */
head = get_vq_desc(dev->vq, iov, &out_num, &in_num);
@ -977,18 +974,13 @@ static bool handle_tun_input(int fd, struct device *dev)
} else if (out_num)
errx(1, "Output buffers in network recv queue?");
/* First element is the header: we set it to 0 (no features). */
hdr = convert(&iov[0], struct virtio_net_hdr);
hdr->flags = 0;
hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
/* Read the packet from the device directly into the Guest's buffer. */
len = readv(dev->fd, iov+1, in_num-1);
len = readv(dev->fd, iov, in_num);
if (len <= 0)
err(1, "reading network");
/* Tell the Guest about the new packet. */
add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len);
add_used_and_trigger(fd, dev->vq, head, len);
verbose("tun input packet len %i [%02x %02x] (%s)\n", len,
((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1],
@ -1490,11 +1482,15 @@ static int get_tun_device(char tapif[IFNAMSIZ])
* the truth, I completely blundered my way through this code, but it
* works now! */
netfd = open_or_die("/dev/net/tun", O_RDWR);
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
strcpy(ifr.ifr_name, "tap%d");
if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
err(1, "configuring /dev/net/tun");
if (ioctl(netfd, TUNSETOFFLOAD,
TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
err(1, "Could not set features for tun device");
/* We don't need checksums calculated for packets coming in this
* device: trust us! */
ioctl(netfd, TUNSETNOCSUM, 1);
@ -1561,6 +1557,16 @@ static void setup_tun_net(char *arg)
/* Tell Guest what MAC address to use. */
add_feature(dev, VIRTIO_NET_F_MAC);
add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
/* Expect Guest to handle everything except UFO */
add_feature(dev, VIRTIO_NET_F_CSUM);
add_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
add_feature(dev, VIRTIO_NET_F_MAC);
add_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
add_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
add_feature(dev, VIRTIO_NET_F_GUEST_ECN);
add_feature(dev, VIRTIO_NET_F_HOST_TSO4);
add_feature(dev, VIRTIO_NET_F_HOST_TSO6);
add_feature(dev, VIRTIO_NET_F_HOST_ECN);
set_config(dev, sizeof(conf), &conf);
/* We don't need the socket any more; setup is done. */