Re: [chrony-users] Re: Why doesn't chrony provide a "maximum error" like ntpd does?

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Ok, makes sense.

So the important bit here is to keep these two values as small as possible and more importantly as "stable" as possible, yes? This way, "jitter", be it network or dispersion, will be low, giving a change to the daemon to keep the offset close to upstream. And a good way to achieve this is to poll the server as much as you can afford, plus keep the link as uncongested as possible.

Are the above steps to right direction?

Thank you for your time. :)


On Thu, 8 Feb, 2018 at 5:26 PM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:

No, it is as said, the maximum uncertainty possible. It is certainly not usual that one leg of the transmission takes all the time, and other leg no time at all. It is certainly not true that the server's clock is off by its own
maximum amount. Thus it is not a good metric of uncertainty.

One can use the fluctuations in the time, but there may be biases in that. Ie,
a good metric of the true uncertainty is hard.

William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/

On Thu, 8 Feb 2018, Abis BIso wrote:

Sounds like it basically the roundtrip-time/2 +max uncert in the server
time. Not that that is a terribly useful number.

Why do you think this is not a useful number?
Isn't this the way to calculate the error of the spot, or RMS, offset you get with chronyc tracking?

As a matter of fact, should this number be used as a metric of uncertainty and not, then what should be used?

Thanks.


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