F-ckin Leap Seconds, how do they work?
Jimmy Hess
mysidia at gmail.com
Wed Jul 4 15:50:46 UTC 2012
On 7/4/12, Robert E. Seastrom <rs at seastrom.com> wrote:
[snip]
> Local clocks have to be consulted much too frequently (logging,
> timestamping, etc) for "just put it in the cloud" to work.
> You might want to read up on NTP (wikipedia provides a reasonable
> introduction).
The NTP daemon could still provide a configuration option to not
implement leap-seconds locally, or ignore the leap-second
announcement received. So the admin can make a tradeoff favoring
Stability over Correctness, of _allowing_ the local clock to become 1
second inaccurate for a short time after the rare occasion of a leap
second; and step it or slew the local clock, eg include the leap
second in the ordinary time correction, averaged over a period of
time instead of a 1 second jump.
The breakage doesn't occur for whatever reason when the time is stepped forward
or backwards, or slewwed.
So accept the inaccuracy and correct the clock in the normal way that
NTP corrects clocks that have drifted.
--
-JH
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