[ntp:questions] NTP Servers in virtual machines

David Woolley david at ex.djwhome.demon.invalid
Wed Jun 25 22:17:12 UTC 2014


On 25/06/14 10:43, Rob Heemskerk wrote:
> Not sure what it's worth and how it is implemented on other virtualisation platforms but according to vmware docs they have a virtual tsc. It is set when the vm is powered on but when the vm is moved to a different host (or resumed more generally) it keeps its original power-on tsc rate.

I think people were assuming that it was impossible to virtualise RDTSC, 
which was why they were arguing that it would isolate you from the 
virtualisation environment.  If it is possible to virtualise it, it will 
be subject to all the time distortions of a virtual environment.

I haven't read a recent enough Intel Architecture specification to know 
whether or not the instruction is trappable, or the TSC counter is 
reloadable.



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