Re: [Xen-users] Release 0.8.0 of GPL PV Drivers for Windows

[jim burns <jim_burn@xxxxxxxxxxxxx>]

On Thursday 28 February 2008 06:07:00 am Pasi Kärkkäinen wrote:
> I can recommend iperf too.
>
> Make sure you use the same iperf version everywhere.

Ok, here's my results.

Equipment: core duo 2300, 1.66ghz each, sata drive configured for UDMA/100
System: fc8 32bit pae, xen 3.1.2, xen.gz 3.1.0-rc7, dom0 2.6.21
Tested hvm: XP Pro SP2, 2002

Method:

The version tested was 1.7.0, to avoid having to apply the kernel patch that 
comes with 2.0.2. The binaries downloaded were from the project homepage 
http://dast.nlanr.net/Projects/Iperf/#download. For linux, I chose the 'Linux 
libc 2.3 binary and (on fc8 at least) I still had to install the 
compat-libstdc++-33 package to get it to run.

The server/listening side was always the dom0, invoked with 'iperf -s'. The 
first machine is a linux fc8 pv domu, the second is another machine on my 
subnet with a 100Mbps nic pipeline inbetween, and the rest are the various 
drivers on a winxp hvm. The invoked command was 'iperf -c dom0-hostname -t 
60'. '-t 60' sets the runtime to 60 secs. I used the default buffer size 
(8k), mss/mtu, and window size (which actually varies between the client and 
the server). I averaged 3 tcp runs.

For the udp tests, the default bandwidth is 1 Mbps (add the '-b 1000000' flag 
to the command above). I added or subtracted a 0 till I got a packet loss 
percentage of more than 0% and less than 5%, or an observed throughput 
significantly less than the request (in other words, a stress test). In the 
table below, 'udp Mpbs' is the observed, and '-b Mpbs' is the requested rate. 
(The server has to be invoked with 'iperf -s -u'.)

machine  | tcp Mbps| udp Mbps| -b Mbps | udp packet loss
fc8 domu |   1563  |     48.6|     100 |    .08%
on subnet|     79.8|      5.4|      10 |   3.5%
gplpv    |     19.8|      2.0|      10 |   0.0%
realtek  |      9.6|      1.8|      10 |   0.0%

Conclusions: The pv domu tcp rate is a blistering 1.5 Gbps, showing that a 
software nic *can* be even faster than a 100 Mpbs hardware nic, at least for 
pv. The machine on the same subnet ('on subnet') achieved 80% of the max rate 
supported by the hardware. Presumably, since the udp rates are consistently 
less than the tcp ones, there was a lot of tcp retransmits. gplpv is twice as 
fast as realtek for tcp, about the same for udp. 19.8/8 = ~2.5 MBps, which is 
about the rate I was getting with my domu to dom0 file copies. I don't expect 
pv data rates from an hvm, but it should be interesting to see how much 
faster James & Andy can get this to go. Btw, this was gplpv 0.8.4.

Actually, pretty good work so far guys!

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