[ntp:questions] Re: Frequency and leapseconds!

David L. Mills mills at udel.edu
Fri Feb 18 15:23:09 UTC 2005


There is a lengthy discussion on these issues in the white papers on the 
NTP project page.


erik corell wrote:
> I have noticed that freq (scaled ppm) in the timex struct from ntp_adjtime() stabilize around a non-zero value on my computers.
> My questions are:
> Is freq the frequency difference from the true calender time 1 sec/sec or is it the difference from a frequency estimation at one point?
> To put is simple: Does for example freq=27.000 ppm always give the same tsc per computer second?
> If so, is it possible to access this 'base rate'?
> Also, is there any way an application can get the total amount of leap seconds since the start of NTP/UTC epoch? For example via a system call or from the NTP server or any other server or from varible long tai in ntptimeval.
> And yet one more: The the possibility of ntp resetting my clock troubles me when I am meassuring difference time. Not enough though to forbid resetting. Is there any way of knowing if the clock was reset during the past few milliseconds or seconds? 
> Thanks a lot.
> Regards,
> Erik Corell

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