Re: problem with system clock
On Sun, Sep 15, 2002 at 11:47:25AM -0400, jon787@tesla.resnet.mtu.edu wrote:
> On Sun, Sep 15, 2002 at 05:52:45PM +0200, martin f krafft wrote:
> > which laptop do you have?
>
> Inspiron 8200
The Dell Inspiron 8200 has a Pentium 4M Processor with SpeedStep.
What this means is that the system can automagically adjust the
processor speed based on usage, to conserve power. The downside is it
messes with software that assumes the processor maintains a constant
speed. This might very well be your culprit.
I don't know if ntpd knows how to handle SpeedStep or not. Even if it
does, it is also possible that there is a subtle implementation bug
causing your clock drift. Keep in mind that ntpd was really tested
with stable servers in mind, not mobile machines with variable CPU
speed.
If accurate time-keeping is really important to you, I suggest look
into the possibility of disabling SpeedStep features on your system.
Also, chrony may (or may not) be better at working around SpeedStep
than ntpd.
If none of the above work, you can run ntpdate in a frequent cron job
to maintain quite accurate time. Alternately, if you purchase a GPS
receiver, I would think that existing tools to communicate with them
could also extract the atomic clock time from them. GPS clocks are
generally very accurate (they need to , so if you pipe the GPS clock
output into date on a regular basis you should be set even without a
network connection. Note that GPS time is c19 seconds off UTC:
http://tycho.usno.navy.mil/gpstt.html
Best of Luck,
-Gleef
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