[154391] in North American Network Operators' Group
Re: F-ckin Leap Seconds, how do they work?
daemon@ATHENA.MIT.EDU (Nick Hilliard)
Tue Jul 3 14:42:24 2012
X-Envelope-To: nanog@nanog.org
Date: Tue, 03 Jul 2012 19:33:05 +0100
From: Nick Hilliard <nick@foobar.org>
To: Saku Ytti <saku@ytti.fi>
In-Reply-To: <20120703175905.GA15977@pob.ytti.fi>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 03/07/2012 18:59, Saku Ytti wrote:
> Leap bugs are NOT known. Most people have no idea unixtime is not
> monotonically increasing.
> I had no idea myself until sunday, I had assumed we really go 59 -> 60 ->
> 00, but we go 59 -> 59 -> 00. So 59.1 can happen before or after 59.2.
> To me this is fundamentally and inherently broken.
Well, yeah, it's not obvious that a minute can have anywhere between 59 and
62 seconds. Certainly if POSIX were being redesigned, they ought to
consider using libtai.
Google's approach to this is interesting:
> http://googleblog.blogspot.ie/2011/09/time-technology-and-leaping-seconds.html
i.e. controlled clock slew until the correct offset is reached, thereby
allowing their developers to assume a monotonic system clock.
Nick
