Chuck Swiger wrote: > Right, OK-- from your earlier mail, you mentioned something about > running with Xen Dom0/DomU. There is absolutely no point to running > ntpd in a guest domain-- you should only try to run ntpd in a normal OS, > or, as a last resort, in the Dom0 domain. The other domains can and > should simply use the HW clock, because latencies and such for the guest > domains are highly unpredictable. There may be a sysctl or Linux /proc > thingy called xen.independent_wallclock which can be toggled.
FWIW... I have a Xen-based VPS. On the newer paravirt_ops kernels, my domU's clock is always independent (and the xen sysctls are unavailable), so I have to run NTP, and it works perfectly fine*. It keeps the clock within 1 ms of the true time, and jitter to its peers is <1.5 ms, and often far below 0.1 ms. (Note: I'm just a dumb VPS user, not a Xen or kernel hacker, so this conversation is nearly over my head. :-P ) * Most of the time. Sometimes the clock drifts <10 ms for a few hours. I suppose it could be Xen's fault, but I don't know. -- _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
