Re: pulse-per-second API status

[<Paul_Koning%Dell.com@localhost>]

On Nov 1, 2013, at 2:04 PM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:

> ...
> But it still may not work in the sense of living up to the expectations
> people have come to have for PPS on serial ports.
> 
> My worry is not that it's not the best time available in some
> circumstances.  My worry is that putting it into the tree will lead to
> its getting used as if it were as good as PPS on anything else, leading
> both to timeservers that claim stratum 1 but give bad chime and to
> people blaming NetBSD for its crappy PPS support when the real problem
> is that they don't understand the USB issues and it _looks_ like any
> other PPS support until you test the resulting time carefully.

Not just PPS on serial ports, but PPS on other hardware.

I don't know this API.  But my first reaction when I saw the designation "PPS" 
is to think of GPS timekeeping boxes and other precision frequency sources that 
have a PPS output.  On those devices, the PPS output is divided down from the 
main oscillator frequency, i.e., you can expect accuracies of 10^-9 for modest 
price crystal oscillators, 10^-10 to 10^-12 for higher end stuff -- and jitter 
in the nanosecond range or better.

It seems rather confusing to have another interface that goes by the same name 
but has specs 6 or more orders of magnitude worse.  How about a different name 
that avoids this confusion?

        paul