[ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
David J Taylor
david-taylor at blueyonder.co.uk.invalid
Wed Jul 4 19:22:37 UTC 2012
"Dave Hart" wrote in message
news:CAMbSiYAqZsDnuNtcyYGn1XU0JBcK4DB3DHUVnsOiJy6hop6w=w at mail.gmail.com...
On Tue, Jul 3, 2012 at 06:20 UTC, David J Taylor wrote:
> Presumably, Dave, if the leap second /had/ been inserted, the second
> message
> would not have happened?
The "would have gone backward 1 times" message was triggered by the
intentional backward step, which wouldn't have occurred at the time it
did if the insertion had slewed as designed. That diagnostic is
supposed to be suppressed when ntpd steps the clock, but the evidence
suggests imperfection. Clearing an additional variable might be all
that's needed.
> Personally, I would correct the missing insertion,
> and treat the second message as a warning that /something/ unexpected had
> happened!
I want to preserve the unexpected aspect by not logging that message
when the clock is expected to step back.
> If the leap second /had/ been inserted, then would ntp have been
> confused in the period before the GPS 18/x started emitting correct
> seconds?
It would quickly notice a 1s offset for the NMEA, which would most
likely be suppressed initially as a popcorn spike. Whether the clock
would be stepped to follow depends on the mix and agreement of
sources.
> I also wonder why the 1-second step doesn't appear to have been reported
> in
> the event log.
I wondered the same thing. I saw a step logged on Windows ntpd with
GPS 18x LVC:
30 Jun 23:59:59 ntpd[2272]: 0.0.0.0 041b 0b leap_event
1 Jul 00:00:00 ntpd[2272]: Leap second announcement disarmed
1 Jul 00:00:15 ntpd[2272]: 0.0.0.0 0413 03 spike_detect -0.999998 s
1 Jul 00:03:45 ntpd[2272]: 2001:4f8:fff7:1::17 962a 8a sys_peer
1 Jul 00:12:29 ntpd[2272]: 0.0.0.0 061c 0c clock_step -1.006282 s
(followed by re-initializing interpolation spew normally seen only at
startup)
You may need to add "+sysall" or more narrowly "+sysevent" to
logconfig in ntp.conf.
Cheers,
Dave Hart
======================================================
Thanks , Dave.
Understood about the suppression of the "would have gone backward 1 times"
message, so me getting it was a [good] indicator that something was amiss.
I agree with ntpd's treatment of these messages.
I don't have a "logconfig" in my ntp.conf, but I could add one if reminded
before any further tests. I presume the omission of these messages is part
of the ntpd "say the least" approach, but I wonder whether on more critical
servers (perhaps those claiming to be at stratum 1?), there should be less
suppression of messages? Against that is the problem of more options
meaning more support queries, and more chance of confusion for the poor
user! <G>.
Cheers,
David
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