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Re: [Xen-users] Xen system hang or freeze

On Thu, Apr 23, 2009 at 10:01:02PM -0400, Peter Booth wrote:
> Nick,
> When you got the "soft lockup" errors were they always with CPU0?
Yes I believe so. But since I updated to the latest debian patched
kernel I havent seen that soft lockup error.

> Do you have any nesting in your LVM definitions?

> Is dom0 making use of LVM?
No it is not.

> Does the host have a wireless card?

> What graphics card does it have?
Just the onboard graphics 01:05.0 VGA compatible controller: ATI
Technologies Inc ES1000 (rev 02)

> There is a Xen 2.6.18 kernel bug that might be related to what you see, 
> as well as a patch:
> http://www.mail-archive.com/debian-kernel@xxxxxxxxxxxxxxxx/msg40893.html
Yes I think that patch is in the latest kernel update which made the
soft lockup messages go away. Odly everyone else that noted the soft
lockup errors only noted them as an annoyance. I don't recall ever
seeing anyone link the messages with any actual undesirable behavior
outside of the msgs themselves.

> I appreciate that this freezing occurs when the system is quiet, but it 
> seems as if the hypervisor CPU scheduler might play some part in this, 
> such that the guest vcpus don't get scheduled on a pcpu. If it were me I 
> would try limiting dom0 to four vcpus - not as a long-term  
> configuration, but to see whether the problem recurred when we know that 
> each domU should have an available CPU.
I was considering that. I also thought it interesting that each of the
domUs are running on vcpu0. I figured they would automatically
distribute to a free vcpu.

Nick Anderson <nick@xxxxxxxxxxxx>

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