Eric S. Raymond writes: > Stiction in this context = "adjacent clock reads could get back the > same value", is that right? Suddenly a whole bunch of things, like > the implications of only updating the clock on a scheduler interrupt, > make sense.
Yes, either the same value or a value that has increased by a token amount that doesn't correspond to the actual increment in time that has passed between the two clock readings. > Therefore I *deduce* that the PLL correction (the one NTP does, not > the in-kernel one Hal tells us is associated with PPS) requires a > monotonically increasing clock. It's the simplest explanation for the > way libntp/systime.c works, and it explains *everything* that has puzzled > me about that code. The thing the PLL (more specifically the loop filter) should care about is that the error estimate it makes is unbiased and has a (relatively) white spectrum. That's exactly what doesn't happen when you have a clock that jumps and you try to read it several times inbetween those jumps. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Wavetables for the Waldorf Blofeld: http://Synth.Stromeko.net/Downloads.html#BlofeldUserWavetables _______________________________________________ devel mailing list [email protected] http://lists.ntpsec.org/mailman/listinfo/devel
