[ntp:questions] Can a clock drift be too big for ntpd?

David L. Mills mills at udel.edu
Fri Oct 26 14:06:06 UTC 2007


As long as you do not use the kernel at other than 100 Hz, things should 
go well. If you do use the kernel at 250 Hz, you should check the 
overshoot of the impulse response; it will probably be in the 10-15 
percent range, which is not good.

It's easy to fix the problem with the kernel and on previous occasions 
folks have patched the Linux kernel to workm even with Hz 1000 Hz. As 
proof, note the Digital RISC has Hz 256 and the Alpha has Hz 1024. As 
the Linux kernelmongers seem to have little interest in fixing this and 
related problems with ntpd, my suggested workaround is to use FreeBSD.


Dennis Hilberg, Jr. wrote:
> Steve Kostecke wrote:
>> FWIW, my 2.6.15 kernel is set to 250Hz and ntpd has no problem with it.
> My stock Mandriva 2.6.17-5mdv kernel is also set to 250Hz with no problems.

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