[libvirt] HELP: after host upgrade to F11, guest runs extremely slow

Gerry Reno greno at verizon.net
Mon May 25 21:42:24 UTC 2009

Gerry Reno wrote:
> Daniel P. Berrange wrote:
>> On Sat, May 23, 2009 at 03:43:12PM -0400, Gerry Reno wrote:
>>> I upgraded the host from F10 to F11 (x86_64) with no issues.  Now when I 
>>> start a F10 (i386) guest it runs very very slow.  I also see messages on 
>>> the guest boot console about "clocksource tsc unstable" and some kernel 
>>> oops.  Once it got far enough to start network I logged in and checked 
>>> the clocksource and it currently is 'acpi_pm' even though the kernel 
>>> line says clocksource=pit.  The available clocksources are acpi_pm, 
>>> jiffies, and tsc.  I do not see 'pit' in the list.  How do I fix this issue?
>> If the guest runs 'extrememly' slowly then the most like thing is that 
>> it has fallen back to using QEMU emulation, instead of KVM hardware
>> acceleration. Check the /var/log/libvirt/qemu/$GUEST.log to see if there
>> is any mesage about not being able to open /dev/kvm.  Also make sure that
>> KVM modules are loaded, and that 'virsh capabilities' lists KVM as a valid
>> domain.
>> Daniel
> Ok, I checked the guest log and it says:
> /dev/kvm: no such file or directory.
> So how do I make this node?  Shouldn't libvirt have made it for us?
Ok, once I got both kernel modules loaded, it created the /dev/kvm 
device and now everything runs fine.


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