Harlan Stenn wrote:


ntp *does* a fit/figure of the expected needed adjustment - your
sentence implies that it does not (at least that's how it reads to me).

No it doesn't.  It is basically a feedback controller.

If you take a modern central heating controller, which varies the output by varying how much of a ten minute cycle the pump is running, you have something similar to version 3 ntpd, except that it used 4 seconds.

The central heating controller will use the measured difference from the target temperature to adjust the on to off proportion, and also include some of the integral of that, to, eventually, remove any remaining offset.

A fitting process would be more like the controller measuring the rate of temperature change when the heat was off, and when it was on, and then calculating exactly how much on to off time to apply in one go. (In practice, it isn't as simple as that for the central heating system, as there is a lag involved for the heat to get from the boiler flame to the the thermostat.



Do you want to re-do the algorithmic analysis of everything NTP does to
make sure that it behaves OK in all circumstances if you bump the limit
to 10000ppm?  And what about kernels that do not currently allow changes
to be applied at that rate?

Nothing is going to work perfectly in every situation. Unfortunately, it is also rare that you don't lose something for what you gain, so you actually have to weight the importance of the ability to cope in different circumstances.

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