[LEAPSECS] What's the point?

[Warner Losh]

On 02/08/2011 17:19, Steve Allen wrote:

> On Tue 2011-02-08T17:03:31 -0700, Warner Losh hath writ:

>> NTP also does everything in UTC time

> No, NTP does not use UTC per se.

> The existing implementations make that specification misleading.

> Rather, NTP uses the internationally approved broadcast time scale.

> The implementations do not know the name of that time scale.

> Only the documentation knows that.

>

> (This is, of course, discounting those site whose sensitivity

> to leap seconds is so great that they are using some sort of

> GPS-based or TAI-based master timeserver for their NTP.)


Pedantically correct, but ntp networks operating in those modes are the 
exception, rather than the rule.  At least with the prevalence of 
GPS-based ntp-servers, setting up a GPS-time network is quite a bit 
easier to pull off than years ago...


> The point of my suggestion for using zoneinfo to propagate the leap

> seconds is that both NTP and POSIX would de facto, silently, and

> inconsequentially change to using TI rather than UTC if the name of

> the internationally approved time scale changed to that.  The systems

> would keep working just fine -- even better if they do not like leaps.

Yes, that would work.  If there were no more leap seconds then this 
would be a workable solution.  only because you don't have either the 
restart or the stale leap data to worry about.



> The documentation could be fixed up later, and the situation would not

> be any more confusing than it is now.


The biggest problem I have with the current state of the art is the need 
to restart programs when new zone files arrive.  At least that was the 
state of the art last time I studied this code in detail, which was 
about 3 years ago.  The second biggest problem I have is using stale 
leap second data to do things like set the current system time before 
you can get the latest info, at which point you're painted into a corner 
with few good solutions.

Warner

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