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Re: [Xen-devel] Xen cluster n/w performance (again!)

To: Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen cluster n/w performance (again!)
From: David Becker <becker@xxxxxxxxxxx>
Date: Tue, 30 Nov 2004 18:42:21 -0500
Cc: Keir Fraser <keir.fraser@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxxx
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" With the domain 0 otherwise idle, what happens if you run 'slurp'
" (attached).

slurp output on domain 0.  xen0 is hit with a 10 second iperf run in the
middle.   (xen0 is idle, there are no xenU hosted, but etherbridge and
xend are running)

Slurped 99.32% CPU, cpu -1
Slurped 99.32% CPU, cpu -1
Slurped 96.52% CPU, cpu -1
Slurped 31.97% CPU, cpu -1
Slurped 54.25% CPU, cpu -1
Slurped 42.67% CPU, cpu -1
Slurped 42.56% CPU, cpu -1
Slurped 49.14% CPU, cpu -1
Slurped 32.32% CPU, cpu -1
Slurped 37.31% CPU, cpu -1
Slurped 30.14% CPU, cpu -1
Slurped 52.59% CPU, cpu -1
Slurped 40.65% CPU, cpu -1
Slurped 99.22% CPU, cpu -1
Slurped 99.32% CPU, cpu -1
Slurped 99.29% CPU, cpu -1

" What's the spec of the most modern machines you've tried Xen on? 

dual 2.8GHz P4xeon 2GB ram.  Sending iperf from another box on that
switch, I see 380Mbps into a xenU on a 2.8GHz host.

Of course the slower CPUs are more available so most of my tests
run there (2.0GHz P4 and 1.4GHz P3).   Is the network overhead so high
that it matters?   They all get wire speed with stock linux.

Another odd thing I saw is that, while on stock linux the 'timer' irq is rock
steady at 100 interrupts per second,  under xen0 the timer irq varies
from 60 to 200 when idle, and hits 5000 per second xen0 is receiving an
iperf stream.

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