Re: Migration problems

[Uri Lublin <uril-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Chris Lalancette wrote:
> All,
>      I've been doing some migration testing of KVM guests, and have been running
> into some problems.  Let me describe the setup and what I've tried, and maybe
> somebody has some ideas about what might be going on here.
>
> When I try to do
> live migration this way, things seem like they work, and it even seems like a
> few instructions get executed on the destination side.  However, fairly quickly
> I'll get "Disabling IRQ #11" on the console of the guest at the destination, and
> the qemu process will just spin at 100%, with no interaction possible.  IRQ #11,
> incidentally, is the IRQ associated with the emulated rtl8139 card.
>
> This led me to suspect the in-kernel PIC/APIC emulation, and, sure enough, if I
> pass -no-kvm-irqchip (on both the source and destination), things are better; I
> can at least migrate from the host to the destination without the "Disabling IRQ
> #11" message.  However, if I put any sort of load on the guest while doing
> migration, I still get a hang-up, even with -no-kvm-irqchip.
>
> Has anyone else seen this, or have ideas where I can start debugging it?
>
> Thanks,
> Chris Lalancette
>   
Hi Chris,

I am chasing migration bug(s) too.
I think the problem lies in userspace and not in the kernel modules.
It seems that for kvm-56 migration works but for kvm-57 it does not.
The problem seems to be related to the qemu-cvs merge: 
25a2e04e5689af63d104de2dea755f30bf643afd
If you run it with -no-kvm migration seems to be working.

The test case I'm using is savevm/loadvm.
After a loadvm my FC6 guest gets double-fault (<qemu-cmdline> -loadvm <id>).
Adding '-no-kvm-irqchip' does not help.
But if I start qemu in a stopped mode (<qemu-cmdline> -S) and 'loadvm 
<id>' in qemu-monitor, it works.
Sometimes after lodavm guest network does work better with '-no-kvm-irqchip'
I am trying to use bisection to find the problematic patch.

Thanks,
Uri.

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/