[ntp:questions] Frequency and leapseconds!

erik corell cii99ec7 at i.lth.se
Fri Feb 18 01:16:51 UTC 2005

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.

Erik Corell

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