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

Anthony Liguori
2008-05-15T15:43:49Z

Avi Kivity wrote:
> Anthony Liguori wrote:
>> 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.
>
> Okay; I'll apply the patches. Hopefully we won't diverge too much
> from upstream qemu.

I am going to push these upstream. I need to finish the page_desc cache
first b/c right now the version of virtio that could go into upstream
QEMU has unacceptable performance for KVM.

Regards,

Anthony Liguori