[Spice-devel] Performance

[Han Pilmeyer]

On 13/03/2013 11:39, Christophe Fergeau wrote:
> On Tue, Mar 12, 2013 at 01:17:26PM +0100, Han Pilmeyer wrote:
>> I thought it might be nice to chime in with my results. I'm running
>> nearly the same versions, except that I'm still using the 0.30
>> version of the spice-guest-tools.
>>
>> I just tested my network speed at the KVM host and in my Windows 7
>> guest. The largest difference was in the ping time which was doubled
>> in the guest (10 ms versus 5 ms in the host). The network bandwidth
>> was almost the same, i.e. in both cases download and upload was over
>> 70 Mbps (to my ISP). Overall, I would say this is not too bad.
>>
>> I usually have reasonable performance watching videos from within
>> the guest. The one thing where I do see issues is with Microsoft
>> Lync while trying to do audio or video calls with colleagues. This
>> works for several seconds (I've seen up to 20 or 30 seconds) and
>> then invariably the connection drops which Lync claims to be due to
>> a flaky network connection. I do not buy this at all. But somehow
>> Lync sees something about the KVM network connection that it doesn't
>> like.
>
> If you are using the virtio network driver, I'd try not using it to see if
> this helps, and vice versa.
>
Excellent idea. I tried this today by replacing the virtio network 
driver with the e1000 driver. Strangely enough this seemed to improve 
the performance. The latency was lower and the bandwidth higher with the 
e1000 driver. I did not notice additional CPU usage, but I haven't done 
any measurements to substantiate that.

Unfortunately it does not change the situation with Lync. I tried it 
both as a NAT and as a bridged network. I also tried a different VPN 
method, but nothing worked. I'll try it tomorrow from the office to see 
if it works when I do not use a VPN.

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