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Re: [Xen-users] Memory squeeze in netback driver

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Memory squeeze in netback driver
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Thu, 11 Jan 2007 18:36:28 +0000
Cc: Scott Moe <smoe868@xxxxxxxxx>
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YOu need to set a dom0_mem on the Xen command line, as described by the other 
poster.

If you don't do this dom0 takes all the system memory and balloons itself down 
in order to start domains.  ISTR the ballooning confuses Linux's memory 
allocator somehow, and this shows up impacting the net driver.

Setting dom0_mem explicitly on the Xen commandline means that the auto 
ballooning isn't necessary (although you may still want to switch off 
auto-ballooning and/or set a new minimum dom0 memory level so that dom0 will 
*never* get shrunk, even if you run out of other memory)

Does this make some sense?  Hopefully it'll fix your problem, please let us 
know.

Cheers,
Mark

On Thursday 11 January 2007 15:23, Scott Moe wrote:
>  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.
>
> Thanks,
> Scott Moe

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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