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[Xen-devel] n/w performance degradation

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] n/w performance degradation
From: Diwaker Gupta <diwaker.lists@xxxxxxxxx>
Date: Mon, 5 Dec 2005 15:11:58 -0800
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Hi folks,

I was to post this over the weekend, but didn't get around to it, and
look in the meanwhile Xen 3.0.0 was released! Good work all around,
but I got some performance problems to report :)

I'm running Changeset 00c349d5b40d269da4fec9510f1dd7c6bb3b3327. This
is a dual CPU machine but I'm currently running with noht, nosmp. All
tests are done using iperf -- both endpoints are sitting on the same
switch on our cluster. The machines have Broadcom BCM5704 NICs.

N/W performance from dom0 seems fine (though I used to get 930+ until
a few days back):

[  6]  0.0-20.0 sec  1.95 GBytes    835 Mbits/sec

However, from a VM, the throughput is really bad:

[  5]  0.0-20.0 sec  1.05 GBytes    450 Mbits/sec

The above numbers are using the BVT scheduler. With the SEDF
scheduler, the numbers are even worse (a VM can't get more than
300Mbps in my tests). I can post concrete figures if people are
interested. I'm _not_ running pipelined netback.

Is anyone else observing such performance problems?

Diwaker
--
Web/Blog/Gallery: http://floatingsun.net
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