Re: ntp problems

[Jean-Christian de Rivaz <jc@eclis.ch>]

Gene Heskett a écrit :
> On Wednesday 07 December 2005 16:56, Jean-Christian de Rivaz wrote:
> 
>>Gene Heskett a écrit :
>>
>>>And, acpi is on, and ntpd is happy with the new bios.  Hurrah!
>>
>>Good news!
>>
>>I wonder if it would be a good idea to add something into the kernel or
>>into ntpd to alert the users that ntpd can't run normaly because of a
>>too fast drift ? Then a BIOS upgrade could be proposed (especially on a
>>nForce2 system). I don't know if it's even realistc.
>>
>>Regards,
> 
> 
> The drift itself wasn't what I'd call excessive, 
> something like 6 minutes in a week, which for 
> mainboard quality crystals is pretty darned good.

ntpd work only on system with a drift of maximum +/-500ppm. This post 
summarize a lot of informations about the problem:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113105244509795&w=2
It was found later that an issue into the nForce2 is the root of the 
problem and that a BIOS update solve it.

6.0 / (60*24*7) * 1e6 = 595.24
6 minutes per week is near 600ppm, it's enough to trigg the problem you 
have seen. Even very cheap crystal are 100ppm at commercial temperature 
range. 100ppm is about 1 minute per week. Some crystal manufacturers 
propose now 30ppm as the default standard at commercial temperature range.

As your watch prove, good cristal can be just a few ppm (about 3.86ppm 
for your watch)

Regards,
-- 
Jean-Christian de Rivaz