[LEAPSECS] Coming of age in the solar system

M. Warner Losh imp at bsdimp.com
Sat Sep 4 08:22:20 EDT 2010

In message: <FB1295B4-A884-4984-8A7A-CA46F9586952 at noao.edu>
Rob Seaman <seaman at noao.edu> writes:

: On Sep 3, 2010, at 11:52 PM, M. Warner Losh wrote:


: > And I'd be pointing to those same discussions where actual practitioners discuss the difficulty in the phrase "just an issue of representation."


: I believe my boss expects me to actually practice in exchange for my

: salary :-)

The problem is that your expectation of what my boss wants differs
from what my boss wants. In general, development management doesn't
care about esoteric edge cases like leap seconds, and would rather
have developers spend the time on more important things.

: > There's both too much automation in leap seconds, and not enough. Nobody cares enough to solve the whole problem


: And right now I'll do the one thing that seems to drive people

: craziest - suggest that system engineering best practices be

: followed to first understand the whole problem - before pursuing a

: solution actually responsive to the requirements. (What a concept!)

Again, you are missing the point: Your engineering solution isn't what
is driving software development. The engineering trade offs you'd
make are different than the ones others would make. It is rare that
you account for absolutely everything in the design, and leap seconds
are often sacrificed to make the job fit within the cost constraints
in place.

: > I've said many times: leap seconds happen to unpredictably to be on the radar of most people.

: >

: > If they were on a regular schedule, where on the average we tried for a |DUT1| < 10s, (or 5s or whatever) we'd have a better chance of getting them right.


: And folks on this side of the aisle have expressed willingness to

: explore these possibilities. Such options were mentioned in the

: ancient Dead Sea Scrolls - er, GPS World article. Why then has the

: only option entertained by "the deciders" been to kill leap seconds

: dead, dead, dead?

I don't know. But I have no control over what other people entertain
as thoughts.

: > Sadly, there's no serious discussion of this middle ground outside of this list.


: So shouldn't we attempt to expand the discussion? Getting the original archives back online would be a good start...and then look into organizing a meeting to engage with key stakeholders - many of who will have never even heard of the ITU proposal (or the ITU for that matter).


: > Of course, it would be cheaper for the software folks to never have to worry about it again.


: There's that assumption again - leap seconds are deadly, but

: absolutely nothing bad can come from redefining every single clock

: on the planet.

That would be an argument against leap seconds too. When they were
introduced, they obsoleted all mechanical clocks because none of them
can handle leap seconds. Even today, the number of clocks that can
handle them is vanishingly small.


: On Sep 4, 2010, at 12:11 AM, Poul-Henning Kamp wrote:


: > In message <6C773408-836C-4D2A-9D37-0A8B7111E675 at noao.edu>, Rob Seaman writes:

: >> The flip side of timekeeping on a spinning pebble skipping through the cosmos is that nothing prevents *also* benefitting from an atomic timescale devoid of the dreaded irregular radix.

: >>

: >> Civil time = mean solar time

: >> Techie time = atomic clock ensemble

: >

: > Absolutely, and that is what people are advocating in various forms.

: >

: > The issue that you in particular, and some astronomers along with you, refuse to acknowledge, is that "techie time" extends all the way to peoples telephones, internet connections, flight safety, medicine production and so on.


: I hereby acknowledge that techie time extends all that long, long, way. And that these are all systems connected to networks. And that those networks are needed to run NTP in the first place. And that the same networks that convey UTC can *also* convey TAI (or some duly blessed transportable realization of atomic time) - or say - hey! - if only there were a handheld device that could magically receive a time signal from outer space, a time signal devoid of those deadly Kryptonite leap seconds.


: > Civil time these days would be more correctly called "ornamental time", because it starts at the VCR, fridge, oven, grandfather clock and other off-line time displays.


: And there are archived discussions pointing out the irrelevancy of such systems to this discussion.


: Certainly civilians have need ("use cases") for both civil time as well as techie time. UTC manages the neat trick of serving both. Don't like that? Split the two. Oh wait! GPS already did that! But oh :-( the Timelords have an even greater distaste for GPS than for UTC...and they also appear to be poised to kill off TAI. This raises the question of why they got in the business of timelordliness in the first place since they don't appear to like any of the many, many, timescales.


: Three birds in the hand are certainly worth a whole lot more than one in a very thorny shrubbery.


: Where are the Knights who say Ni! when you need them?


: Sir Rob is running away now...

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