Re: [ANNOUNCE] kvm-guest-drivers-windows-2

Anthony Liguori
2008-05-15T13:57:07Z

Avi Kivity wrote:
> Anthony Liguori wrote:
>> FWIW, virtio-net is much better with my patches applied.
>
> The can_receive patches?
>
> Again, I'm not opposed to them in principle, I just think that if they
> help that this points at a virtio deficiency. Virtio should never
> leave the rx queue empty. Consider the case where the virtio queue
> isn't tied to a socket buffer, but directly to hardware.

For RX performance:

right now
[ 3] 0.0-10.0 sec 1016 MBytes 852 Mbits/sec

revert tap hack
[ 3] 0.0-10.0 sec 564 MBytes 473 Mbits/sec

all patches applied
[ 3] 0.0-10.0 sec 1.17 GBytes 1.01 Gbits/sec

drop lots of packets
[ 3] 0.0-10.0 sec 1.05 GBytes 905 Mbits/sec

The last patch is not in my series but it basically makes the ring size
512 and drops packets when we run out of descriptors. That was to valid
that we're not hiding a virtio deficiency. The reason I want to buffer
packets is that it avoids having to deal with tuning. For
vringfd/vmdq, we'll have to make sure to get the tuning right though.

Regards,

Anthony Liguori