Messages in this thread | | | Date | Wed, 7 Jan 2009 19:31:27 +0000 | From | Alan Cox <> | Subject | Re: [ntpwg] Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009 |
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> time, causing time to jump backwards by 1s (or violate POSIX time_t's > invariant that midnight time_t is % 86400 == 0). This jump backwards > is a pita in the kernel, and violates the assumption that many > programs have that time doesn't flow backwards.
They can slew the clock slowly as well. There is a wonderful quote from one of the summaries of the POSIX committee discussions on time that says quite simply "the posix clock is not guaranteed to be accurate"
As it currently stands the kernel contains sufficient support that at the point you know a leap second is coming you can adjust the second length marginally over the entire period.
The current behaviour is an implementation decision. Jumping on a second shouldn't be an issue to most people, jumping back is asking for badness but isn't in fact used in the world today. Slewing the entire day so that each second is 1/86400 of a second longer or shorter wouldn't be noticed by anyone.
Alan
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