[ntp:questions] Re: ntpd, boot time, and hot plugging

David L. Mills mills at udel.edu
Fri Feb 4 04:39:00 UTC 2005


Tom,

I don't think you have the model right. The ntpd never "backgrounds 
itself", but keeps on ticking according to a state machine which 
controls whether or not to do a direct frequency measurement rather than 
the usual incremental feedback loop, which depends on whether the 
frequecy file is present. The only thing the -g does is exit the daemon 
when the clock is first set.

Dave

Tom Smith wrote:

> Brad Knowles wrote:
> 
>> At 12:30 AM +0000 2005-02-04, Tom Smith wrote:
>>
>>>  1) step the clock to a "good enough" time
>>>        do this within a few seconds
>>>        block while doing it
>>>        don't touch/change the pre-computed drift while doing this
>>>  2) start ntpd
>>>  3) start time-dependent services
>>
>>
>>
>>     Thinking about this some more, what I hear you saying is that ntpd 
>> should not background itself until such time as it has calculated the 
>> initial offset and stepped the clock as necessary to get you within 
>> normal slew distance, at which point it backgrounds itself and 
>> continues normal startup operations, starts working on 
>> calculating/updating the drift, etc....
>>
>>     At least, it should have this as an optional startup mode, perhaps 
>> as a part of "-g".
>>
> 
> Bingo. And DON'T TOUCH THE DRIFT until the second phase starts.
> 
> I'd also say that should always be the startup mode, -g or no -g
> (or at least -g should be implied during that first phase, whether
> or not it's requested for the "permanent" phase).
> 
> -Tom
> ________________________________________________________________________
> Tom Smith                       smith at alum.mit.edu,smith at cag.lkg.hp.com
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