Proposal - drop the GPSD JSON driver
hmurray at megapathdsl.net
Sat Oct 22 18:17:07 UTC 2016
> What ntpd gets from a clock source is a series of pairs asserting "at system
> time X I believe it was UTC time Y".
> Are you telling me there is no value in minimizing the time from X to when
> the sample triggers a correction, and the variation in that time?
> Basic servocontrol theory tells me that control lag is the enemy of
> precision and tends to produce whiplash effects. Does that not apply here?
Not "no value", but it depends on the time constant of the PLL filter.
Delays of a small fraction of the time constant won't be problem.
In the normal case, the data is put into a buffer and isn't processed until
several/many seconds later. So except for the last sample, any delay and/or
jitter under a second doesn't matter.
Things will get more interesting if you try to run with minpoll of 0.
My current thinking is that we should either use a cleaned up SHM or the same
struct over a socket. The socket will fit in with the big select and has a
reasonable chance of working well with minpoll of 0.
These are my opinions. I hate spam.
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