Our Linux instances running on Amazon EC2 had no issues since we are not running ntpd on these servers and adjtimex returns status as 64 (clock unsynchronized).

I think the Xen host takes care of the synchronization and we need not do it in the guest OS. (see http://serverfault.com/questions/100978/do-i-need-to-run-ntp...).

Is this fine or should we run ntpd for better accuracy?