Commit 398f187d authored by Rusty Russell's avatar Rusty Russell
Browse files

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: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 9254926f

Documentation/lguest/lguest.c

+20 −14
Original line number Diff line number Diff line
@@ -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. */

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