time drift

[Bruce Cran]

Volker Jahns wrote:
> On Thu, May 15, 2008 at 09:53:02PM +0200, Volker Jahns wrote:
>> 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
>>> 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.
> A few years ago a time drift problem had been observed by a German freebsd
> user (http://www.freebsd.de/rachive/de-bsd-questions.200304/0643.html).
> Time drift 15 sec every half hour, ntpd dies away running on his machine.
>     
> Setting kern.timecounter.hardware to TSC had been recommended as a solution.

There's also a FreeBSD PR open about this problem: 
http://www.freebsd.org/cgi/query-pr.cgi?pr=i386/123462


-- 
Bruce