[ kvm-Bugs-2948108 ] qemu-kvm fails to migrate properly in 0.12.2

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Bugs item #2948108, was opened at 2010-02-08 16:06
Message generated for change (Comment added) made by iggy_cav
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=893831&aid=2948108&group_id=180599

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Category: qemu
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Lance Albertson (ramereth)
Assigned to: Nobody/Anonymous (nobody)
Summary: qemu-kvm fails to migrate properly in 0.12.2

Initial Comment:
I'm using Ganeti and encountered a problem [1] with migrating KVM virtual machines. I have confirmed that this is not a problem specific to Ganeti and is also happening to the Libvirt project [2].

When migrating from host A to host B, everything goes fine however the guest VM (running CentOS 5.4) clock changes to approximately 600 seconds in the future. When attempting to migrate back to host B, the VM locks up and stops responding. However, if you fix the clock prior to syncing back to host A, the migration happens however the clock on the VM literally stops so the guest is pretty unusable. 

I tried the same scenario using Ubuntu 9.10 for the guest OS and has different issues. Upon migrating to host B, the clock on the guest VM was ahead by over 3 days into the future. Then when I migrate it back to host A the VM locks up hard.

I can confirm I have no problem using migration when using 0.11.1.

Here's the detail information about our setup:
Hardware: Intel(R) Xeon(R) CPU 5160  @ 3.00GHz
qemu-kvm: 0.12.2
kernel: 2.6.29-hardened
Linux OS: Gentoo Hardened

If you need more information, please let me know and I'll be happy to provide it.

Thanks-

[1] http://groups.google.com/group/ganeti/browse_thread/thread/9b2c556557e749cf
[2] http://thread.gmane.org/gmane.comp.emulators.libvirt/20771

----------------------------------------------------------------------

>Comment By: Brian Jackson (iggy_cav)
Date: 2010-02-09 09:55

Message:
Can someone try this?

http://www.mail-archive.com/kvm@xxxxxxxxxxxxxxx/msg28046.html

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Comment By: ttt (mrt2k9)
Date: 2010-02-09 03:50

Message:
Using acpi_pm both on hosts and guests (Debian 5.0 AMD64) seems to work. I
now did 20-30 live migrations or so and it worked like a charm. Thanks!

----------------------------------------------------------------------

Comment By: Lance Albertson (ramereth)
Date: 2010-02-08 18:33

Message:
Any idea why kvmclock is causing this issue? Has there been any recent
changes to that part of qemu-kvm?

Thanks for the tips on CentOS, I'll give that a try and see if that works
as a workaround for now.

----------------------------------------------------------------------

Comment By: Brian Jackson (iggy_cav)
Date: 2010-02-08 18:30

Message:
I think 5.4 had kvmclock backported to it... I just think it doesn't have
the same /sys adjustments for clock, so you have to use the no-kvmclock
thing or possibly something else.

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Virtualization_Guide/chap-Virtualization-KVM_guest_timing_management.html

has some tips for disabling it I think

possibly just clocksource=acpi_pm is needed

----------------------------------------------------------------------

Comment By: Lance Albertson (ramereth)
Date: 2010-02-08 18:13

Message:
It seems to work if I use something like acpi_pm for the clock source (on
Debian). The clock also seemed to stay in time. I haven't tested it on the
other OS's but it seems that CentOS doesn't even use kvmclock (which means
sense considering the age of the kernel).

----------------------------------------------------------------------

Comment By: Brian Jackson (iggy_cav)
Date: 2010-02-08 17:54

Message:
guest

you can either use the no-kvmclock boot param or choose a different clock
in:
/sys/devices/system/clocksource/clocksource0/current_clocksource

possible values are in:
/sys/devices/system/clocksource/clocksource0/available_clocksource

----------------------------------------------------------------------

Comment By: Lance Albertson (ramereth)
Date: 2010-02-08 17:27

Message:
Are you wanting me to try this on the guest or host system?

----------------------------------------------------------------------

Comment By: Brian Jackson (iggy_cav)
Date: 2010-02-08 17:09

Message:
This has been mentioned a few times in irc and possibly on the mailing
list. No one has really come up with a fix. Can you try without kvmclock?

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=893831&aid=2948108&group_id=180599
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