guest machines falls behind time

Binary package hint: kvm

We have seen that guest machines can fall considerably behind wall clock time. This is apparently a well know phenomenon with virtual machines, and is the subject of a VMware whitepaper (http://www.vmware.com/pdf/vmware_timekeeping.pdf).

In this whitepaper, it is stated that running NTP guest machines is not a good idea, and it is reasonable to imagine that the NTP server would go crazy when the clock constantly is lagging.

A better solution is to have a cron script that runs regularly, updating the time to the value of the host's hardware clock.

We are running with Ubuntu JeOS, where NTP is a required package. For the above reasons, this is not a good idea. A package containing a time synchronizing cron script is a much better solution. Ubuntu JeOS should ship with such a package.

Another solution (?) could be a modification to KVM, so its virtual clock device would be tied to the host clock.

Details:
Host machine runs Ubuntu server 7.10.
kvm is a locally back-ported hardy package: QEMU PC emulator version 0.9.0-cvs (kvm-59)