Messages in this thread | | | From | "Ulrich Windl" <> | Date | Thu, 15 Sep 2005 08:49:21 +0200 | Subject | Re: NTP leap second question |
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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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