[LEAPSECS] private smear goes public

Brooks Harris brooks at edlmax.com
Thu Dec 1 20:49:33 EST 2016


Hi Warner,
On 2016-12-01 08:02 PM, Warner Losh wrote:
> On Thu, Dec 1, 2016 at 4:28 PM, Stephen Colebourne <scolebourne at joda.org> wrote:
>> On 1 December 2016 at 19:45, Brooks Harris <brooks at edlmax.com> wrote:
>>> As I read it I think Google's intention is to publish their method and
>>> algorithm in the hopes others may follow it. It would be better if everybody
>>> did it the same way, but it will remain to be seen if others will choose to
>>> follow the example.
>> The page reads clearly enough to me that:
>>
>> - Google will leap over 20 hours this time because it is too late to
>> change their plans
>> - They plan to leap over 24 hours next time to match Amazon and others
>> - The propose an informal "standard" of 24 hours leaps henceforth
>>
>> If all the big IT players agree on a 24 hour leap, 12 hours either
>> side of midnight UTC, then we have all moved a step forward. Even more
>> so if they write up the approach as a formal standard.
>>
>> The next issue is that there are then two types of NTP server -
>> smeared and non-smeared - and no way to tell the difference. Call me
>> naive, but that seems like a perfectly soluble problem, either within
>> NTP or external to it.
>>
>> For the record, I think that both leap-smeared and leap-accurate
>> broadcast time have value, but it should be easily possible to tell
>> which is being received. I also desperately want there to be a name
>> for the proposed informal standard, so we can all talk about it.
> I find the two different types of time amble evidence that leap
> seconds are evil and must die. Nobody knows what to do with them. Few
> get it right so we have to resort to tricks to pretend they aren't
> there. And people that care wind up disappointed that more things
> don't get them right. Clearly the bastard stepchild of time that
> should be relegated to the dustbin of history.
I'm sure you know I'm on the other side of that opinion; that UTC with 
Leap Seconds is a very good, even brilliant, solution to the 
inconvenient fact of the Earth's wobbly rotation to preserve the age old 
tradition of timekeeping by the sun. This in the same way Gregorian 
calendar 'solved' the length of the year.

But, regardless of our opinions, Leap Seconds are here to stay until at 
least 2023 and probably much longer. So, "smear" is with us to protect 
the 86400-second-day systems. There's no avoiding this, really, because 
those systems have no hole into which the 86401th peg can be put. And, I 
might add, who ever tested the systems end-to-end for a negative Leap 
Second?

-Brooks


>
> Warner
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