From owner-freebsd-arch  Fri Oct 26 15:11:35 2001
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Date: Fri, 26 Oct 2001 16:25:09 -0700 (PDT)
From: Julian Elischer <julian@elischer.org>
To: Matthew Dillon <dillon@apollo.backplane.com>
Cc: John Baldwin <jhb@FreeBSD.ORG>,
	Poul-Henning Kamp <phk@critter.freebsd.dk>, arch@FreeBSD.ORG,
	Peter Wemm <peter@wemm.org>, Bakul Shah <bakul@bitblocks.com>
Subject: Re: 64 bit times revisited..
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trouble is, that ticks are:
1: not guaranteed to be constant
2/ inaccurate.

also,
you can represent ticks in terms of 1/(2^64) units, certainly to the
accuracy of the crystals that we use for timekeeping at this time.


On Fri, 26 Oct 2001, Matthew Dillon wrote:

> 
> :>     The phrase 'no freaking way' comes to mind.
> :> 
> :>     You guys are outsmarting yourselves.  Seconds, ok.  That's it.  Nothing
> :>     else.  The *VAST* majority of programs only need seconds, it would be
> :>     utterly stupid to require that they mess around with some weird fixed
> :>     point quantity when all they want is seconds, no matter how supposedly
> :>     'simple' that messing around is (i.e. '>> 64' is not acceptable).
> :> 
> :>                                               -Matt
> :
> :Umm.  Dude, this is for the kernel's internal representations.  We can massage
> :it in libc or in the kernel before it gets to userland.  We do have to maintain
> :compatibility.  Slow down and think about this for a second.
> :
> :-- 
> :
> :John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
> 
>     The best kernel-internal time representnation is ticks, with a simple
>     baseline cache mechanism to convert it to other formats (e.g. as
>     required by NFS, UFS, userland, etc...).  Nothing beats ticks...
>     a binary fixed point format doesn't even come *close* to being better
>     then straight ticks.
> 
> 						-Matt
> 
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