On Thu, 04 Nov 2010 17:03:33 +1300, Steven Ellis mail_lists@stevencherie.net wrote:

I've got a three Centos 5.5 KVM severs, but only one of them is

presenting

guests with the kvm-clock source.

The two servers I'm not seeing kvm-clock on have Athlon x2 64bit processors.

The other server with kvm-clock has a Phenom II X6 1090T Processor.

I've checked the system configuration and all the boxes have the same set of RPM packages. To confirm that the issue was physical hardware specific I migrated a VM from the Athlon to the Phenom server

and

the kvm-clock source appeared.

Any ideas why I'm not seeing kvm-clock with my Athlon X2 processors, or

is

there another difference I haven't caught?

Well it looks like the issue relates to constant_tsc.

Out of the 3 boxes only the Phenom has constant_tsc in the CPU flags. There appears to be some kernel list references here - * http://www.mail-archive.com/kvm@vger.kernel.org/msg10193.html

This finally led to the following docs * http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.5/html/Virtualiz...

Looks like I need to do some tweaking at the grub level for my Athlon X2 boxes

Steve