Guest Time drift

Some tips from RedHat's Virtualization Host Configuration and Guest Installation Guide, if you have time drifts (mainly for windows),

Using the Real-Time Clock

WIN XP, WIN 2003 Server

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 Server, WIN8, WIN2012 Server, WIN10, WIN2016 Server

In your windows guest:

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