[ntp:questions] Lep seconds

Unruh unruh-spam at physics.ubc.ca
Fri Jan 4 18:20:55 UTC 2008


markn_46 at yahoo.com (Mark Newman) writes:


>Unruh - thanks for responding.  You are the only one
>who did.  

>I certainly did not mean to disparage NTP time.  I
>have spec'ed that it be used on our system.  Where I
>run into problems is when a leap second occurs. 

Since no leap seconds have occured in the past 2 years, and before that for
7 years,  I doubt that you
have every seen a problem when a leap second occurs. 

>According to everything I've read when  NTP signals
>the operating system that the second is occurring it
>also outputs time.  It uses the POSIX standard method

?? I have no idea what that phrase "outputs time" means.

>- duplicate a second (or in some cases stretch the
>last second).  This causes confusion when a time
>sample is taken before the leap second and one during
>the leap second.  The UTC standard (which only
>addresses ascii time representations) actually counts
>the second 0..60 rather than 0..59.

Yes. And since that one second occurs about once every 2-3 years, on Dec 31
or June 30, who cares. Again what is your problem that you are trying to
fix? 


>At this point I am obligated to use UTC and NTP.

>Tht missing second is causing me to get a lot of heat.

>From whom? There is no missing second. Noone has seen a leap second in
quite a while. Who is giving you the heat? And if they do, explain to them
how UTC works.


> Does anyone know of a way to get NTP to count the
>leap second rather than to delete it?  Or am I missing
>the point.

???? I have no idea what you mean. Most leap seconds add a second to the
year-- Just as leap years add a day ( or do you also have trouble with leap
years, and want us to go on lunar time, which does not have them.)




>>I don't want to step on anyones toes but I am getting
>>a lot of heat over using a POSIX compliant ntp re
>leap
>>seconds.  The 1 second error inserted can cause a lot
>>of trouble.

Again, heat from whom? You have never told us what problem you are trying
to solve. 



>Exactly what heat are you getting and what trouble is
>it causing you?
>Perhaps if you tell us the problem rather than your
>solution, we could come
>up with a solution.


>>I now that the Olsen mod changes most Unix/Linux time
>>processing to handle the leap second in a
>>theoretically correct manner rather than being POSIX

>I have no idea what "a theoretically correct manner "
>is. The Posix IS a
>theoretically correct manner. 

>>compliant.  Is there a similar mod for NTP.  I am
>>hoping that there is a mod that will cause NTP to
>>supply theoretical UTC (even if it is not ascci).

>NTP DOES supply both theoretical and practical UTC. 

>I think what you are worried about is that you want
>your system to provide
>something like TIA-- Atomic time-- which has no leap
>seconds. I believe the
>Olsen mods have your system clock run on atomic time
>and then use the
>leapsecond file and the zoneinfo file for your region
>to translate that to
>your local time.

>You could just set up ntp to add 33 sec to its time,
>and you would have
>atomic time.




>>                            Mark




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