[ntp:questions] Leap seconds
David L. Mills
mills at udel.edu
Tue Jan 25 02:54:32 UTC 2005
Brad,
Management frequently has rather amazing procedures when leap seconds
and spring/fall steps occur. The IBM Sysplex Timer carefully calibrates
the clock offsets for leap seconds, locl time zone offset and TAI/UTC
(as specified by the operator). However, and particularly in the fall
step, I know for a fact that some IBM systems just stop all processing
during the hour after the switch. I assume these machines are not being
used for air traffic control, but then all times used in that and the
maritime community are only in UTC.
Dave
Brad Knowles wrote:
> At 1:36 PM -0800 2005-01-24, mayer at gis.net wrote:
>
>> NTP is the one that decides how much to change the clock and
>> tells the O/S. Moving the clock backward by 1 second, which is
>> in effect what a leap-second does, can have major negative effects
>> on systems that depend on the time being a monotonically increasing
>> variable.
>
>
> A leap second would never cause the time to be moved backwards. A
> leap second shouldn't ever cause the time to be jumped forwards,
> either. It should simply result in an extra second that occurs during
> that minute.
>
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