David Lord wrote:
> I use ntpd to sync to internet time. A few of my pcs
have clocks too
> far out for ntpd to work effectively as the natural
clock drift is at
> a greater rate than ntpd can lock to. The fix is to
adjust the value
> of TIMER_FREQ in kernel configuration to offset the
system clock
> drift. I aim for within -10 ppm to 0 ppm. Of course
temperature and
> power supply voltage can cause fairly wide variation so
near is good
> enough vs >>500 ppm drifts of some pcs. Other pcs
are within 30 ppm
> without any tweaking.
>
> eg. from K6X400_0.32
> ! # K6X400 is approx -60 ppm so aim for > +50ppm
change
> ! # default 1193182
> ! # for +68
> ! options TIMER_FREQ=1193250
Thank you, David. This is very helpful, if still a bit
mysterious.
Here's what I'm seeing:
cherry$ grep ntpd /var/log/messages |head
Nov 15 11:09:29 cherry ntpd[29870]: time reset -2.326574 s
Nov 15 11:09:29 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 11:14:53 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 11:34:10 cherry ntpd[29870]: time reset -3.754409 s
Nov 15 11:34:10 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 11:39:33 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 11:54:35 cherry ntpd[29870]: time reset -2.699728 s
Nov 15 11:54:35 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 11:59:57 cherry ntpd[29870]: frequency error -512 PPM
exceeds
tolerance 500 PPM
Nov 15 12:16:59 cherry ntpd[29870]: time reset -3.915989 s
cherry$ config -x /netbsd | grep TIMER
options TIMER_FREQ=1189200
I don't know what units TIMER_FREQ is in. Taking a naive
guess, I add 512
to it, giving me 1189712. Since you suggest
overcompensating, perhaps
1189800?
Is that the idea?
--jkl
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