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Re: [Xen-users] Very slow domU network performance

To: Winston Chang <winston@xxxxxxxxxx>
Subject: Re: [Xen-users] Very slow domU network performance
From: Matt Ayres <matta@xxxxxxxxxxxx>
Date: Wed, 05 Apr 2006 12:09:06 -0400
Cc: "Stephen C. Tweedie" <sct@xxxxxxxxxx>, xen-users <xen-users@xxxxxxxxxxxxxxxxxxx>
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Winston Chang wrote:
On Apr 4, 2006, at 1:59 PM, Stephen C. Tweedie wrote:

The packet loss is as follows:
domU --> domU  0% (using
domU --> domU  0% (using domU eth0 IP address)
dom0 --> domU  ~100% (only 7 of 38464 made it!)


There have been a number of weird checksum problems identified in the
past with Xen's networking; a checkin was just made a day or two ago
which cleans up the checksum handling in a way which may well help here.
We'll have to see whether an updated dom0/domU kernel improves things

I ran the test with the latest xen-unstable build. The results are the same.

When I ran 'xm sched-sedf 0 0 0 0 1 1' to prevent domU CPU starvation, network performance was good. The numbers in this case are the same as in my other message where I detail the results using the week-old xen build -- it could handle 90Mb/s with no datagram loss. So it looks like the checksum patches had no effect on this phenomenon; the only thing that mattered was the scheduling.

What was the previous weight of domain 0? What is the weight assigned to the domU's and do the domU's have bursting enabled?

Thank you,
Matt Ayres

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