[ntp:questions] Re: Linux Kernel functions usef by NTP for controlling the system clock

Ulrich Windl Ulrich.Windl at RZ.Uni-Regensburg.DE
Thu Jun 22 08:11:43 UTC 2006


ndprasad at gmail.com (DeviPrasad Natesan) writes:

> I have a few questiions regarding the use of the function adjtime.
> When does the NTP takes decision on changing the "offset"
> (ADJ_OFFSET_SINGLESHOT) and when "tick" (ADJ_TICK).

AFAIK, ntpd never changes "TICK", and it uses adjtime() when not using the NTP
kernel interface. (maybe see the "slew always" if it still exists)

Regards,
Ulrich


> 
> Is there any provision to control the frequency of the osciallator if
> we have an TCXO or OCXO without changing the "tick" in the kernel to
> achieve frequency correction. How does the NTP scale when using this
> way..Any experience by the people on using this way..

If you need to adjust TICK for TCXO or OCXO, something is severely broken
IMHO. The continuous frequency correction in the kernel is not done with
"tick".

Ulrich




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