[ntp:questions] Re: tinker step 0 (always slew) and kernel time discipline

David L. Mills mills at udel.edu
Fri Sep 22 16:25:37 UTC 2006


"disable kernel" does exactly and precisely that. In that case 
corrections are handled as if the kernel code does not exist.

Ordinarily, to disable the step correction also disables the kernel. 
Your "tinker step 0" exposed a bug, now fixed, in which the kernel was 
not automatically disabled in that case.


Joe Harvell wrote:
> I have an application that is sensitive to step corrections and am 
> considering using 'tinker step 0' to disable them altogether.  However, 
> I noticed a thread on this topic in February 2005 
> (http://lists.ntp.isc.org/pipermail/questions/2005-February/004468.html) 
> that suggested setting 'tinker step 0' without explicitly using 'disable 
> kernel' will essentially yield unpredictable behavior.
> So what does disable kernel do?  Does it disable the NHPFL algorithm?  
> Is this algorithm synonomous with the "kernel time discipline?"  So when 
> "disable kernel" has been used, how is the clock frequency adjusted?  
> Also, why is the kernel time discipline disabled when a correction of > 
> 0.5 seconds is required?
> ---
> Joe Harvell

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