Guest Time drift

Some tips if you have time drifts (mainly for windows)

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/chap-Virtualization_Host_Configuration_and_Guest_Installation_Guide-KVM_guest_timing_management.html

WIN XP - WIN2003

Using the Real-Time Clock with Windows Server 2003 and Windows XP guests

Windows uses the both the Real-Time Clock (RTC) and the Time Stamp Counter (TSC).

For Windows guests the RTC can be used instead of the TSC for all time sources, which resolves guest timing issues.

To enable the RTC for the PMTIMER clock source (usually uses the TSC), add the option /usepmtimer to the end of the boot line in boot.ini.

WIN VISTA - WIN7 - WIN2008

In your windows guest:

C:\Windows\system32>bcdedit /set {default} USEPLATFORMCLOCK on