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To: John Hein <jhein@timing.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 17 Sep 2008 09:34:10 CST."
	<18641.9074.499346.988999@gromit.timing.com> 
Date: Wed, 17 Sep 2008 15:43:07 +0000
Message-ID: <47836.1221666187@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: arch@freebsd.org, Brooks Davis <brooks@freebsd.org>
Subject: Re: 64 bit time_t 
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In message <18641.9074.499346.988999@gromit.timing.com>, John Hein writes:

>So for systems where we don't care about compatibility (where a
>product is built from scratch and we don't have to worry about 3rd
>party binary libs/programs), the problems mentioned by brooks & phk
>disappear.
>
>No one wants to play the performance or atomic access card?

I know of only the kernel variable "time_second" where that would be
a concern, and since we have 64bit atomic writes, I consider that
a non-concern.

At any rate, even if you write it with two 32bit writes, you will
only have one chance for a race every 136 years.

Next time you have the chance is:

critter phk> bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
2^31-1
2147483647
critter phk> date -r 2147483647
Tue Jan 19 03:14:07 UTC 2038

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.