Re: clock drift

["Paul J. Lucas" <pauljlucas@mac.com>]

On Wed, 25 May 2005, Joerg Sommer wrote:

> Does anyone know where this drift comes from?

	It could be just a miscalulation by the kernal as to how fast it
	thinks the CPU is.  The kernel isn't perfect.

	Anyway, your drift problem is nothing.  I initially had a drift
	of about 10 seconds per hour for my Mac Mini.  (My hardware
	clock was correct.)

	You can help NTP out by adjusting the TICK value in
	/etc/default/adjtimex.  I figured out the correct value by:

		1. Shut down ntpd.
		2. On the hour, set the system clock to match the
		   hardware clock.
		3. Wait 1 hour.
		4. Examine the system clock and note the difference.

	In my case, a good value for TICK is 10028.  Now the drift is
	small enough that ntpd can handle it.

	- Paul