Reset kernel time (PLL/FLL)

Question

ntp trys to adjust the kernel's time variables, in order to improve the performance of a free-running time.

I am searching a way to reset these variables, but I can't find a programm/command to do so.

Thanks everyone for helping me!

Answer 1

I think you must be talking about the NTP Drift file. From Dr Mill's (originator of NTP) website:

During operation ntpd measures and corrects for incidental clock frequency error and occasionally writes the current value to a file specified by the driftfile /etc/ntp.drift configuration command. If ntpd is stopped and restarted, it initializes the frequency from this file and avoids the potentially lengthy interval to relearn the correction.

Deleting the drift file and restarting the ntp daemon so solve your problem. In debian, you'd do the following (note that the drift file may be stored in different places...you can always use the "locate" command to find it):

invoke-rc.d ntp stop
rm /var/lib/ntp/ntp.drift
invoke-rc.d ntp start

Answer 2

ntptime:

DESCRIPTION

This program is useful only with special kernels described in the A Kernel Model for
Precision Timekeeping  page. It reads and displays time-related kernel variables using
the ntp_gettime() system call. A similar display can be obtained using the ntpdc
program and kerninfo command.

You can set:

• frequency offset
• estimated error
• clock offset
• time constant

I am assuming those are the kernel time variables you are talking about. Please let me know if there are others you are interested in