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[Xen-users] Memory squeeze in netback driver

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Memory squeeze in netback driver
From: "Scott Moe" <smoe868@xxxxxxxxx>
Date: Thu, 11 Jan 2007 10:23:15 -0500
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I have had servers run Xen 2 without rebooting Dom0 for most of a year.

I am working now on a very similar machine with Xen 3.03 and Debian etch.

My network setup is slightly customized. I have 3 IP's and use network-route in xend-config.spx. I specify vif-route as the vif script in the DomU config for 2 of my VM's.

I also create a bridge in /etc/network/interfaces. I have two other VM's that only interface to this bridge and the VM's with their own IP's have a second vif on the bridge. I specify the vif-bridge script in vif config for these interfaces.

Everything boots and runs great, for several hours. Yesterday, for example, the machine was rebooted in the morning. It ran for 11 hours without errors, then the kern.log started to fill up with this message:
xen-net: memory squeeze in netback driver
This went on for 13 hours at a rate of something like 5 to 10 messages per second. Then the log shows each vif on the bridge entering disabled state. The vif's with dedicated IP's were not mentioned in the log, but this morning only the dom0 ip was responsive. When I ssh into dom0 and try to ping the IP's routed to VM's I see no route to host. I looked at route and everything was listed correctly.

I hope someone has seen a similar problem and can give me some insite. My experience is limited but to me this smells like a memory leak. Perhaps there are updates that will fix this problem but have not made it into the Debian etch packages.

Scott Moe
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