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

[Anthony Liguori <anthony@codemonkey.ws>]

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

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