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

To: "jim burns" <jim_burn@xxxxxxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Re: Release 0.9.1 of GPL PV Drivers for Windows
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Mon, 26 May 2008 12:57:55 +1000
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Thread-topic: [Xen-users] Re: Release 0.9.1 of GPL PV Drivers for Windows
> 100 Mb/s, but this is dom0<->domu, which is all software nics.
> the
> window size helps some, but not significantly, and I want a test that
> closer to real application usage. I'm not testing peak theoretical,
> especially with iometer.

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.


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