From: Chris Wedgwood <chris@cybernet.co.nz>
To: Colin Plumb <colin@nyx.net>, tytso@MIT.EDU
Cc: andrejp@luz.fe.uni-lj.si, linux-kernel@vger.rutgers.edu
Subject: Re: GPS Leap Second Scheduled!
Date: Thu, 10 Sep 1998 11:45:15 +1200 [thread overview]
Message-ID: <19980910114515.A20254@caffeine.ix.net.nz> (raw)
In-Reply-To: <199809092013.OAA10252@nyx10.nyx.net>; from Colin Plumb on Wed, Sep 09, 1998 at 02:13:42PM -0600
On Wed, Sep 09, 1998 at 02:13:42PM -0600, Colin Plumb wrote:
> - gettimeofday() never returns the same value twice (documented BSD
> behaviour)
Ouch... gettimeofday(2) only presently has usec resolution. I suspect
we can make this report the same value twice on really high end boxes
(667MHz Alpha maybe, 400Mhz Sparcs?), if not now, in a year or so.
Even a P.ii 600 or so can probably manage it.
Sure... this is fixable and not hard to fix, but it requires breaking
binary compatibility.
The attached code on a PPro 200 gives me results of 2 usecs, using a
P.II 300 and SYSENTER semantics, you can probably get this to less
that 1usec.
> I don't know of a pretty way. What I'd like, as I said, is a
> defined kludge, so that there is a defined mapping between struct
> timeval and struct timespec and UTC in the vicinity of a leap
> second.
I'm not sure about a sane kludge for mapping to/from the semantics we
already have, but how about we just declare the existing API buggy
under some (rare circumstances) and create a new one with flags to
show whether or not a leap second is currently under way, much the
same as is done for daylight savings time with time zones. (You can
have two 2:30ams, only one of which tough is DST, the other is
non-DST).
-Chris
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next prev parent reply other threads:[~1998-09-09 22:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-09-09 20:13 GPS Leap Second Scheduled! Colin Plumb
1998-09-09 23:45 ` Chris Wedgwood [this message]
1998-09-09 23:55 ` Chris Wedgwood
1998-09-10 8:36 ` Rogier Wolff
1998-09-10 17:05 ` Oliver Xymoron
1998-09-10 22:02 ` Ryan Moore
[not found] <19980914165757.A17479@tantalophile.demon.co.uk>
[not found] ` <199809150603.XAA29073@cesium.transmeta.com>
[not found] ` <19980915100729.02790@albireo.ucw.cz>
[not found] ` <35FF1838.6E247F0C@his.com>
1998-09-17 11:51 ` Jan Echternach
-- strict thread matches above, loose matches on Subject: below --
1998-09-11 22:49 Ethan O'Connor
[not found] <no.id>
1998-09-10 6:34 ` Jamie Lokier
1998-09-11 6:18 ` Michael Shields
[not found] <299BBE59294E@rkdvmks1.ngate.uni-regensburg.de>
[not found] ` <98090822315400.00819@soda>
1998-09-09 0:59 ` H. Peter Anvin
1998-09-09 8:00 ` Chris Wedgwood
[not found] ` <199809092149.RAA06993@hilfy.ece.cmu.edu>
1998-09-10 1:37 ` H. Peter Anvin
1998-09-10 15:05 ` Theodore Y. Ts'o
1998-09-12 19:57 ` Feuer
1998-09-09 16:35 ` David Lang
1998-09-09 4:46 Colin Plumb
1998-09-09 19:08 ` Theodore Y. Ts'o
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