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SubjectRe: NTP leap second question
On 14 Sep 2005 at 11:54, john stultz wrote:

> On Wed, 2005-09-14 at 11:39 -0700, George Anzinger wrote:
> > It appears that a leap second is scheduled. One of our customers is
> > concerened about his application around this. Could one of you NTP
> > wizards help me to understand NTP a bit better.
>
> First: I'm not an NTP wizard by any means, but I'll see if I can't help.
>
> > First, I wonder if we suppressed the leap second insert and time then
> > became out of sync by a second, would NTP "creap" the time back in sync
> > or would the one second out of sync cause it to quit?
>
> The ntpd's slew-bound is .125s I believe, so a second offset would cause
> ntpd to adjust the time using stime()/settimeofday(). You could run ntpd
> with the -x option which forces it to always slew the clock. This
> however could cause the initial sync to take quite some time.
>
>
> > Assuming NTP would do the "creap" thing, is there a way to tell NTP not
> > to insert the leap second?
>
> If I recall, leapsecond implementations are a pretty contentious issue.
> Some folks have suggested having the kernels note the leapsecond and
> slew the clock internally. This sounds nicer then just adding or

No! Never slew a leap second: It will take too long! It's all over after one
second. If you slew, you time will be incorrect for an extended time.

Ulrich


> removing a second, but I do not know how that would affect synchronizing
> between a number of systems. So I'll defer the larger discussion to the
> real NTP wizards.
>


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