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

Daniel P. Berrange berrange at redhat.com
Sun May 24 12:59:48 UTC 2009

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

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