I've got a CentOS VM (release 6.2) running under HyperV. I have integration services installed (part of base now), and CentOS shows the current clocksource is hyperv_clocksource, however my time in the VM is about 10 minutes fast after a week of uptime. My understanding of the new IC and plugable clocksource is that this shouldn't happen any more. Is there any additional configuration necessary to get the plugable clocksource to "work?"

I know there are plenty of links about setting kernel options to PIT and various stuff like that, but those all seem to pre-date the integrated clocksource support, and as I understand it shouldn't be needed anylonger. Nor should ntpd nor adjtimex.