[time-nuts] Divide by five

Paul tic-toc at bodosom.net
Sun Nov 9 14:51:12 EST 2014


On Sun, Nov 9, 2014 at 1:11 PM, Bob Camp <kb8tq at n1k.org> wrote:

> NTP's aim is mainly to throw out bad clocks and pick one as best. We would
> more likely want to combine the outputs and use all of the good clocks we
> have.
>

By default NTP makes a paper clock from all acceptable sources (up to some
maximum) to discipline a/the/its system clock.  One source is special -- "The
mitigation rules select from among the survivors a *system peer* from which
a set of system statistics can be inherited and passed along to dependent
clients, if any" -- but not for the discipline process.  Unfortunately
"peer" can be a bit confusing in this context so I prefer source.

This is not to say that the NTP paper clock algorithm is particularly good
or suitable for other purposes and the code may be simplified because the
assumption is a relatively small (<10) number of "survivors".


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