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Re: [Xen-users] Re: Release 0.9.1 of GPL PV Drivers for Windows

On Sunday May 25 2008 10:57:55 pm James Harper wrote:
> FWIW, on my test system (1.8GHz AMD 1210):
> iperf Dom0->DomU 200MBit/sec
> iperf DomU->Dom0 840MBit/sec
> If I go up to -w 256K I gain about 10-20% performance. I'm not sure, but
> I suspect that the reason that Dom0->DomU speeds are so slow is that
> xennet has to turn the gso (large send offload) packets into individual
> packets manually, and also has to do manual checksumming. When the
> entire process is CPU bound (eg all software NICs) then anything extra
> the CPU has to do is going to make a difference.

Curious - my dom0->domu numbers are faster than the reverse, both for tcp & 
udp, tho' much more so for udp:

> For iperf, I had to setup some batch files ahead of time that I could click 
> on in My Computer. For a tcp test, 'iperf-1.7.0 -c dom0-name -t 60 -r':

> domu->dom0: 31 Mb/s (no loss)
> dom0->domu: 36 Mb/s

> For a udp test, requesting a 10Mb/s bandwidth, 'iperf-1.7.0 -c dom0-name -t 
> 60 -r -b 10000000' gave:

> domu->dom0: 2.6 Mb/s
> dom0->domu: 9.9 Mb/s

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