[ntp:questions] Leap second to be introduced in June

William Unruh unruh at invalid.ca
Mon Jan 12 05:10:24 UTC 2015

On 2015-01-12, brian utterback <brian.utterback at oracle.com> wrote:
> On 1/11/2015 10:40 PM, William Unruh wrote:
>> On 2015-01-12, Mike S <mikes at flatsurface.com> wrote:
>>> On 1/11/2015 7:16 PM, William Unruh wrote:
>>>> If that public source is responsible it will pass on to your
>>>> system the fact that there is a leapsecond, and your system will "stop"
>>>> for a second at the last second of June.
>>> A system which properly implements leap seconds will do no such thing. 
>>> It will properly account for a minute with 61 seconds, and will tick 
>>> from 23:59:59 to 23:59:60 then to 00:00:00.
>>> There is no "stopping," or any other discontinuity.
>> Well, actually as I understand it, ntpd does stop the cclock for that
>> second, making sure that every successive read of the clock during that
>> time is later than the one before by a few microseconds. until the
>> second ends.
> That is not the case. That is the behavior that the kernel reference

I presume the "That" refers to ntpd. I will accept that it is the Linux
kernel does that. I also admit I do not know how windows impliments leap

> code implements which is not part of ntpd. It is up to the individual OS
> leap second implementers to determine the behavior they implemented,
> which may or may not behave this way.

But if you do not do that then ntpd will, after a while, jump the time
(since the time to do 1 sec at 500PPM would be 2000 sec, or about an
hour. Of course it would have to first decide that the clock was out by
a second. AGain, I do not know how Windows handles it, but it is ntpd
which does the jumping in that case.
Ie, there could well be a discontinuity.


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