[ntp:questions] NTP Servers in virtual machines

David Woolley david at ex.djwhome.demon.invalid
Mon Jun 23 11:28:53 UTC 2014


On 23/06/14 12:03, Rob Heemskerk wrote:

> As kernels are tickles nowadays response times to clock interrupts and (interrupt backlogs) do not seem to be relevant anymore.

Tickless kernels still use clock interrupts; they just schedule them 
only when actually needed.  In fact they can make it worse, in that they 
can tweak the timing so as to aggregate several wakeups.
>
> Could we say it is safe to run ntp servers on a virtualized platform or do we still need a few (4?) dedicated pieces of hardware to run our internal NTP servers?

No.

Normal virtualised machines are not intended for hard realtime 
applications.  Also, the host clock can and should be disciplined using 
NTP, so there is a risk double correction.



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