[ntp:questions] Speed of ntp convergence

David Woolley david at ex.djwhome.demon.co.uk.invalid
Wed Nov 5 21:32:58 UTC 2008


Speechless wrote:

> b) you are experiencing a genuine problem not encountered by anyone else

Lots of people report poor startup behaviour.  Two have abandoned ntpd 
on this newsgroup in the last few weeks because of this.

> 
> It should not be necessary to spell it out for you that if you are
> dissatisfied with the results you are getting, then you need to DO
> SOMETHING DIFFERENT to GET DIFFERENT RESULTS that might be more to your
> liking.

It is perfectly valid to try and get the product improved, rather than 
simply encouraging everyone to vote with their feet.
> 
> For example, my assistant runs ntp on her budget priced general purpose
> machine and she is absolutely thrilled that her machine is able to keep 
> time with an accuracy of "within one second" of her wrist watch.  She is

ntpd considers accuracies of worse than about 128ms to be broken, so 
anyone who is only interested in 1 second accuracy is either getting a 
lot better than they expect, or doesn't really need ntpd.

If you are only interested in 1 second accuracy, you don't get 
convergence issues, because ntpd will go into error recovery long before 
you reach a second.  If you are out by that much at startup, you will be 
rapidly brought into that range.  If you go out during operation, there 
will be an upwards of 15 minutes delay, but that will start at 128ms, 
and the time will be abruptly corrected, normally long before it reaches 
1 second.  None of that really depends on the algorithms that make ntpd 
what it is.

> not in this news group complaining about ntp and you are.  One of the 
> things you might try to do DIFFERENT, is to use a better quality wrist 
> watch when checking the time on your machine.
> 

> 




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