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Re: [Xen-users] System Freezes

To: Jonathan Tripathy <jonnyt@xxxxxxxxxxx>
Subject: Re: [Xen-users] System Freezes
From: Pierre POMES <ppomes@xxxxxxxxxxxx>
Date: Wed, 16 Jun 2010 11:45:53 -0400
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Hi Jonathan,

It limits the number of cores the dom0 will use: cat /proc/cpuinfo will report only one CPU core. Same for top, htop, and so on.

Regards,
Pierre

Hi Pierre,
 
Excellent advice. I'll give that a shot later this evening and get back to you. What does "(dom0-cpus 1)" actually do?
 
Thanks


From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx on behalf of Pierre POMES
Sent: Wed 16/06/2010 15:18
To: Bruce Edge
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] System Freezes

Hi all,

I also had similar issues with Ubuntu server 10.04 64b, Xen 4.0, kernel 2.6.32.12 "opvs" and kernel 2.6.32.10 "XenLinux" (from Andrew Lyon). I am only using PV guests.

When the system is non responsive, you should see "CPU #x stuck for yy seconds" on the console (or using dmesg, if you get any answer from it).

I solved the problem using "(dom0-cpus 1)" in the xend config file. The problem did not occur again after this modification.

Can you try it and let us know ?

Pierre

What dom0 kernel & xen version?

Try toggle the Xen console, Ctrl-A 3 times, then 'h' for help to see if you get output.

-Bruce


On Wed, Jun 16, 2010 at 1:29 AM, Jonathan Tripathy <jonnyt@xxxxxxxxxxx> wrote:
Hi Everyone,
 
I wish to gather whether the following issue is a disk or CPU issue.
 
U have a Xen host, running Ubuntu 10.04 64 bit Dom0. It has a single hard drive.
 
FOr testing purposes, I ran 2 DomUs. Both running Ubuntu 10.04 64bit PV. From a remote machine, I ssh'ed into the 2 VMs.
 
On one session I ran a script that would constantly download a file from the net. Delete it, then repeat.
On the other session, I ran a script which ran dd to create a 1G file, delete it, and repeat.
On my remote machine, I also ran another 2 terminals to ping each DomU.
 
Everything seemed ok, until I decided to move a window on the Dom0's screen (Via VGA port and USB keyboard and mouse). The system just became unresponsive for a couple of minutes. Pings stoped working, ssh sessions woudn't refresh..
 
Now, I also had an HVM pfsense machine running, which has a real NIC passed through to it. I can't be 100% sure, however I think that its web GUI was still responsive when accessing it via the real NIC's IP. This leads me to think that the only machine that freezes is the Dom0, which includes the bridge that the DomUs are connected to.
 
Does the above sound like a disk issue or CPU? What can I do to help things? Maybe I should run a Dom0 without a windows manager?
 
Thanks

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