[ntp:questions] Extracting ntpq like information programmatically

unruh unruh at invalid.ca
Sun Mar 31 01:10:14 UTC 2013

On 2013-03-29, Brian Utterback <brian.utterback at oracle.com> wrote:
> On 3/29/2013 1:26 PM, Claudio Carbone wrote:
>> I mean that, when I have certain timings from different machines, if I 
>> correct them by their average offset from a common source, doesn't 
>> this augment the precision of the measure?
>> I'm using a single external source to compare all other clocks. 
> In a word, no. How do you determine their average offset? You can use 
> their own estimate of that (which is what ntpq does) but taking the 
> average is not adding any precision since NTP is already correcting for 
> the offset it measures. You can measure the offset relative to the 
> system making the test (say by running ntpdate), but then you are 
> introducing a new source of error so it doesn't help you. As unruh said, 
> if there was a way to improve the accuracy of the measurement over the 
> network like that, NTP would already be doing it.

Well, modulo Mills' prejudices as to how ntpd should work. In short, if
the user has different requirements from those that Mills had, there may
be a way of using the data differently to get better results. But you
really really have to know what you are doing. 

> Brian Utterback.

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