From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "M. Warner Losh" <imp@bsdimp.com>
Cc: mayer@ntp.isc.org, linasvepstas@gmail.com, david@lang.hm,
hancockr@shaw.ca, kyle@moffetthome.net,
slashdot@jameshallam.info, goodgerster@gmail.com,
davidn@davidnewall.com, linux-kernel@vger.kernel.org,
ntpwg@lists.ntp.isc.org, pretzalz@techhouse.org,
burdell@iruntheinter.net, nick@nick-andrew.net,
jeff@kosowsky.org
Subject: Re: [ntpwg] Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009
Date: Wed, 7 Jan 2009 19:31:27 +0000 [thread overview]
Message-ID: <20090107193127.0bec8ad8@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20090107.103947.1324582654.imp@bsdimp.com>
> 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
next prev parent reply other threads:[~2009-01-07 19:33 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-02 19:25 Linas Vepstas
2009-01-02 20:04 ` Diego Calleja
2009-01-02 20:25 ` Robert Hancock
2009-01-03 6:32 ` David Newall
2009-01-03 6:37 ` Ben Goodger
2009-01-04 8:43 ` David Newall
2009-01-04 9:00 ` Kyle Moffett
2009-01-04 10:03 ` David Newall
2009-01-04 11:13 ` david
2009-01-04 23:15 ` David Newall
2009-01-04 23:25 ` Chris Adams
2009-01-05 0:01 ` David Newall
2009-01-05 0:41 ` Alan Cox
2009-01-05 8:43 ` David Newall
2009-01-05 19:47 ` Alan Cox
2009-01-05 0:29 ` david
2009-01-04 23:37 ` David Newall
2009-01-05 1:05 ` david
2009-01-05 0:14 ` David Newall
2009-01-05 0:21 ` Ben Goodger
2009-01-05 6:34 ` David Newall
2009-01-05 23:03 ` Linas Vepstas
2009-01-05 0:44 ` Alan Cox
2009-01-05 5:48 ` Linas Vepstas
2009-01-05 14:33 ` Nick Andrew
2009-01-05 16:08 ` Linas Vepstas
2009-01-05 17:51 ` david
2009-01-05 17:42 ` Linas Vepstas
2009-01-06 2:27 ` john stultz-lkml
2009-01-06 4:53 ` Linas Vepstas
2009-01-06 5:00 ` Linas Vepstas
2009-01-06 19:40 ` [ntpwg] " M. Warner Losh
2009-01-06 19:50 ` M. Warner Losh
2009-01-07 3:50 ` Danny Mayer
2009-01-07 4:52 ` Linas Vepstas
2009-01-07 10:03 ` David Newall
2009-01-07 17:24 ` M. Warner Losh
2009-01-08 16:51 ` Magnus Danielson
2009-01-07 14:34 ` Danny Mayer
2009-01-07 15:42 ` Linas Vepstas
2009-01-07 19:23 ` Danny Mayer
2009-01-07 16:04 ` john stultz
2009-01-07 17:36 ` M. Warner Losh
2009-01-07 17:39 ` M. Warner Losh
2009-01-07 19:31 ` Alan Cox [this message]
2009-01-07 19:42 ` M. Warner Losh
2009-01-08 3:57 ` Danny Mayer
2009-01-08 4:42 ` M. Warner Losh
2009-01-08 10:48 ` Alan Cox
2009-01-08 10:56 ` Alan Cox
2009-01-08 22:22 ` David Mills
2009-01-08 15:02 ` M. Warner Losh
2009-01-08 18:57 ` Marshall Eubanks
2009-01-08 20:09 ` Steve Allen
2009-01-12 16:11 ` Pavel Machek
2009-01-12 17:07 ` [ntpwg] " M. Warner Losh
2009-01-12 21:45 ` Valdis.Kletnieks
2009-01-06 2:31 ` Nick Andrew
2009-01-06 1:59 ` David Newall
2009-01-06 2:18 ` Chris Adams
2009-01-06 2:51 ` Nick Andrew
2009-01-06 9:40 ` Alan Cox
2009-01-07 1:17 ` Nick Andrew
2009-01-07 9:37 ` Alan Cox
2009-01-07 9:46 ` David Newall
2009-01-07 9:54 ` Alan Cox
2009-01-07 10:18 ` David Newall
2009-01-07 10:52 ` Alan Cox
2009-01-07 13:45 ` David Newall
2009-01-07 14:10 ` Alan Cox
2009-01-07 14:36 ` David Newall
2009-01-07 15:40 ` Alan Cox
2009-01-10 9:46 ` David Newall
2009-01-07 22:13 ` Chris Adams
2009-01-07 13:33 ` Chris Adams
2009-01-07 13:37 ` Alan Cox
2009-01-07 14:12 ` David Newall
2009-01-07 14:09 ` David Newall
2009-01-07 21:42 ` Chris Adams
2009-01-04 11:35 ` Valdis.Kletnieks
2009-01-05 0:08 ` David Newall
2009-01-06 3:53 ` Valdis.Kletnieks
2009-01-04 17:20 ` Kyle Moffett
2009-01-03 7:00 ` Chris Adams
2009-01-04 8:41 ` David Newall
2009-01-02 20:29 ` Linas Vepstas
[not found] ` <8752a8760901021328t545a0327v58faebe1e921680a@mail.gmail.com>
2009-01-02 21:29 ` Ben Goodger
2009-01-03 0:21 ` Chris Adams
2009-01-03 2:23 ` Duane Griffin
2009-01-03 3:45 ` Linas Vepstas
2009-01-03 4:41 ` [PATCH] " Chris Adams
2009-01-03 4:52 ` Duane Griffin
2009-01-03 18:01 ` [PATCH] v2 " Chris Adams
2009-01-03 19:04 ` Duane Griffin
2009-01-03 20:01 ` Linas Vepstas
2009-06-08 2:18 ` Ben Hutchings
2009-06-18 22:34 ` Chris Friesen
2009-06-18 22:58 ` Ben Hutchings
2009-06-18 23:48 ` Chris Friesen
2009-01-06 2:21 ` john stultz-lkml
2009-01-06 2:25 ` Chris Adams
2009-01-06 4:35 ` Linas Vepstas
2009-01-03 3:49 ` Linas Vepstas
2009-01-03 4:02 ` Ben Goodger
2009-01-03 4:46 ` Duane Griffin
2009-01-03 4:50 ` Ben Goodger
2009-01-03 22:58 ` Jeffrey J. Kosowsky
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