Re: [PATCH] virtio_net tx performance fix

[Anthony Liguori <aliguori@us.ibm.com>]

Dor Laor wrote:
> On Mon, 2008-01-28 at 09:32 -0600, Anthony Liguori wrote:
>   
>> Hi Dor,
>>
>> How are you measuring performance?  The numbers I've gotten with netperf 
>> before and after your patch are:
>>
>> tx - 647.27mbit
>> rx - 89.22
>>
>> tx - 27.82
>> rx - 79.93
>>
>>     
>
> I've been testing with iperf (patched with Ingo's fix).
> I also tested tcp/udp (udp tx is only 550Mbps with the patch, w/o it's
> only 220Mbps)
>   

FWIW, I repeated with an scp test copying a 200mb file from /dev/shm on 
the host to the guest and vice versa.  rx performance is around 3-4 
MB/sec.  Without your patch, tx performance is around 40 MB/sec whereas 
with your patch performance is around 30 MB/sec.  So the tx drop is 
definitely exaggerated by netperf.  I'm definitely not seeing an 
increase in throughput though.

Could you try a similar scp test?  What sort of networking setup are you 
using?

My guest kernel and host kernel are both 2.6.24 (from Ubuntu Hardy).

Regards,

Anthony Liguori