[ntp:hackers] Frequency initialization bug

[Brian Utterback]

Nevertheless, it is the same bug. Removing the file was your workaround. 
No file, no initialization.

Well, Dave, I am over my shortlived desire for self-destruction and will 
try to refrain from providing
you with that agenda.Besides, I will be too busy hiding under my bed 
this week, since Friday the
13th falls on a Sunday this month. Specifically, next Sunday. Horrors!

Harlan, I believe that this should address bug 306 and it can be closed.

David L. Mills wrote:

> Brian,
>
> The bug had nothing to do with the issue of removing or not removing 
> the frequency file. It had only to do with the kernel frequency 
> initialization when and only when the "disable kernel" command was 
> given. If I were to kill you I would need a much more ambitions agenda.
>
> Dave
>
> Brian Utterback wrote:
>
>> David L. Mills wrote:
>>
>>> Guys,
>>>
>>> Found an evil one which could well explain the occasional frequency 
>>> torque to  +-500 PPM. During initialization the ntpd discipline loop 
>>> and the kernel loop are initialized from the frequency file. As 
>>> operation continues, the kernel manages the frequency and ntpd reads 
>>> whatever the kernel computes, but doesn't do anything with the value 
>>> other than to calculate the stability for eyeball display and 
>>> statistics. This all works well.
>>>
>>> But, if the kernel is explicitly disabled (disable kernel command), 
>>> the kernel is never called, except at initialization, and that's the 
>>> rub. Since the configuration file has not been parsed yet, there is 
>>> no way to know that the kernel frequency should not be initialized 
>>> as indicated by the disable kernel command. The result is every time 
>>> ntpd is started the current ntp.drift contents torque the kernel and 
>>> the daemon then has to compensate for that offset. If the intrinsic 
>>> hardware error is high, like 300 PPM, the ntpd loop frequency could 
>>> well hit the stops.
>>>
>>> I fixed this by moving the loop frequency initialization from 
>>> ntp_util.c to ntpd.c so it gets called only after configuration is 
>>> complete. If disable kernel is in the configuration file, the kernel 
>>> will never be called.
>>>
>>> Dave
>>>
>>> _______________________________________________
>>> hackers mailing list
>>> hackers at support.ntp.org
>>> https://support.ntp.org/mailman/listinfo/hackers
>>
>>
>>
>> Dave, you are killing me. I reported this as bug 306 back in August, 
>> which started much discussion
>> through October, and was never resolved because you shot down every 
>> proposal to change it. You
>> said that if the drift file is incorrect, you should just remove it 
>> before starting ntpd.
>>
>> Brian Utterback
>> brian.utterback at sun.com
>>
>
> _______________________________________________
> hackers mailing list
> hackers at support.ntp.org
> https://support.ntp.org/mailman/listinfo/hackers