Virtio-net: Add multi queues in multi threads

In order to support 2 vq pairs for virtio-net, this patch create 2
sockets in one tap interface,  2 vq pairs(rx/tx) and 2 threads in
device model, So one vq pair has one thread and one socket in tap
corresponding.

On my SkyLake desktop with crosvm and ubuntu 18.04 guest:
If run one iperf server on host and one iperf client in guest, 2 vq
pairs has the same netwrok bandwidth as 1 vq pair, the bandwidth is
5.99Gbits/sec

If run two iperf server on host and two iperf client in guest,
In 1 vq pair mode, two iperf cliens bandwidth are 3.19Gbits/sec and
3.18Gbits/sec.
In 2 vq pairs mode, two iperf clients bandwidth are 4.87Gbits/sec and
4.86Gbits/sec.
So 2 vq pairs improve net bandwidth 52.7% compared with 1 vq pair in
this case.

BUG=chromium:1064482
TEST=Run iperf test in guest

Change-Id: I1fa14d7e24085552dc828a89a883d4a2ada34789
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2099754
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Xiong  Zhang <xiong.y.zhang@intel.corp-partner.google.com>
Reviewed-by: Stephen Barber <smbarber@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/linux.rs b/src/linux.rs
index 3370c1e..6eb1ef7 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -593,7 +593,7 @@ fn create_tap_net_device(cfg: &Config, tap_fd: RawFd) -> DeviceResult {
             .map_err(Error::CreateTapDevice)?
     };
 
-    let dev = virtio::Net::from(tap).map_err(Error::NetDeviceNew)?;
+    let dev = virtio::Net::from(tap, 1).map_err(Error::NetDeviceNew)?;
 
     Ok(VirtioDeviceStub {
         dev: Box::new(dev),