NTPD unable to adjust local clock

Joerg Sonnenberger joerg at britannica.bec.de
Wed Apr 6 11:39:31 PDT 2005

On Tue, Apr 05, 2005 at 06:44:33PM -0700, Matthew Dillon wrote:
>     I've investigated this a bit more.  OpenBSD's ntpd is just not up to
>     snuff.  It has no PLL locking code at all and the result is that the
>     timekeeping is constantly out of whack, oscillating back and forth as
>     ntpd does its occassional adjtime() based corrections.  If it isn't
>     out of whack due to the clock being fast or slow, it's out of whack due
>     to the adjtime() call trying to correct 5 minutes worth of creep with a
>     single call.  My test boxes are oscillating between -10ms and +25ms of
>     error and they have fairly accurate clocks.  Any boxes with inaccurate 
>     clocks are going to be hit hard.  A 1 second error is easy to accumulate
>     with a clock that is only 0.3% off.

Well, I get differences between ntp0.fau.de and ntps1-1.cs.tu-berlin.de
of 0.003, so the system time oscillating somewhat is not critial.

After watching the output of ntpd for a while, there seems to be a bug.
The offset goes down from initially 1.138025 to 0.048019 and 0.024507,
but it gets addjusted to 0.663717s right afterwards. That's bogus.


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