time drift

[Volker Jahns]

On Thu, May 15, 2008 at 12:18:57PM -0700, Chuck Swiger wrote:
> On May 15, 2008, at 11:57 AM, Volker Jahns wrote:
> >FreeBSD 6.2 running on X86 hardware (FSC) shows a remarkable time  
> >drift
> >
> >running ntpdate every half hour shows that the system looses about  
> >10-14 sec each time.
> >15 May 10:06:48 ntpdate[7200]: step time server 192.53.103.108  
> >offset -13.799602 sec
> >15 May 10:36:48 ntpdate[7515]: step time server 192.53.103.108  
> >offset -12.813941 sec
> >15 May 11:06:48 ntpdate[7879]: step time server 192.53.103.108  
> >offset -13.651921 sec
> >15 May 11:36:50 ntpdate[8079]: step time server 192.53.103.108  
> >offset -11.109298 sec
> >15 May 12:06:50 ntpdate[8289]: step time server 192.53.103.108  
> >offset -11.836499 sec
> 
> While you should run ntpdate -b at system boot, running ntpdate  
> periodically via cron is not the right thing to do-- you should run  
> ntpd instead, and that will figure out the intrinsic correction your  
> chosen system clock needs to keep better time via the ntp.drift file.
Running ntpd on this system results in time drift of approx. 1-2 hrs a day. That is not an acceptable option.
> 
> You should also take a look at the output of "sysctl  
> kern.timecounter", and possibly switch to a different mechanism, if  
> the existing choice doesn't work out well for your machine...
Thanks for the hint.

-- 
Volker Jahns, volker at thalreit.de