[LEAPSECS] Lets get REAL about time.

Warner Losh imp at bsdimp.com
Sun Jan 22 11:44:40 EST 2012

On Jan 21, 2012, at 6:44 AM, Poul-Henning Kamp wrote:

>> My question, though: if the offset is in TAI, and you have to

>> support "UTC", how do you get your leap second tables to do the

>> conversion?


> The reason for TAI is that way the kernel will not need the leapseconds

> only userland will.


> libc will need an updated table of leap-seconds to give you UTC,

> and if you hand it a timestamp that is more than some set delta-T

> from the last entry in the leapsecond table, it will return E2BIG

> rather than give you a potentially wrong timestamp.

So I can't do operations on UTC time stamps that are more than 6 months in the future?

> NTP can transfer the leap-second table these days, and all sorts

> of software update mechanisms could as well.

One of the problems right now with the 'right' database is that you have to update it and already running programs don't notice this update since it would be prohibitively expensive to do a stat call on each time operation. Any clever ideas around this issue?


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