Re: pulse-per-second API status

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> Also, see below - 1ms strikes me as pretty bad for PPS.
> Sure, but it's vastly better than nmea timecode, which is what the
> other choice is.

Oh, sure; as I said in other words upthread, I'm not arguing that it's
not a good choice for you - I'm arguing that it's not a good choice for
the main tree.

>> But if NetBSD enables PPS on ucom, there's going to be an
>> expectation that it is good enough for stratum-1 timekeeping, like
>> PPS on real serial ports.
> I don't think there's any such expectation created.

If I didn't know enough about USB to know how unavoidable some of its
delays were, I'd have such an expectation in that situation.

>> It does work in the sense that it's the best chime available in that
>> dismal a situation.
> It's not that dismal - it's pretty typical.

Well, when I wrote that, I was going on the 100ms figure; if your
network is so bad that NTP can't do better than 100ms, I think it's
fair to call that `dismal'.

>> 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.
> People who expect the same as serial PPS are confused,

In some respects...

> and we are not responsible for that.

...my argument is that NetBSD _would_ be responsible for that, by
making this look just like PPS on any other serial port, right up until
discovering that the resulting chime is bad.

> 1 ms (if it is that, and it seems to be) is decent compared to
> non-local networks.

It is.  But for stratum 1, which is what PPS normally drives, it's
pretty awful.

> And it's better than interpreting NMEA or some other timecode on
> serial, and one can configure that to be s1.

I'd argue that should be fixed, then.

Of course, I'm not the one doing the work, nor the one passing on it,
nor the one taking the flak if it turns out I'm right, nor even someone
going to be using it, so it's no skin off my nose.  I've said my piece
and I'll let you and the rest of the NetBSD people decide what to do;
pointing out a risk is all I feel I need to do here - whether you want
to take it is up to you.

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