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Date:      Wed, 19 Dec 2012 02:03:32 -0800
From:      Davide Italiano <davide@freebsd.org>
To:        Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc:        Ian Lepore <freebsd@damnhippie.dyndns.org>, Alexander Motin <mav@freebsd.org>, phk@onelab2.iet.unipi.it, freebsd-current <freebsd-current@freebsd.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>
Subject:   Re: API explosion (Re: [RFC/RFT] calloutng)
Message-ID:  <CACYV=-Eg542iHm9KfujPvCzZrA4TqepEBVA8RzT1YOHnCgfJnA@mail.gmail.com>
In-Reply-To: <14604.1355910848@critter.freebsd.dk>
References:  <50CF88B9.6040004@FreeBSD.org> <20121218173643.GA94266@onelab2.iet.unipi.it> <50D0B00D.8090002@FreeBSD.org> <50D0E42B.6030605@FreeBSD.org> <20121218225823.GA96962@onelab2.iet.unipi.it> <1355873265.1198.183.camel@revolution.hippie.lan> <14604.1355910848@critter.freebsd.dk>

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On Wed, Dec 19, 2012 at 1:54 AM, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
> --------
> In message <1355873265.1198.183.camel@revolution.hippie.lan>, Ian Lepore writes
> :
>>On Tue, 2012-12-18 at 23:58 +0100, Luigi Rizzo wrote:
>
>>I'm not so sure about the 2^k precision.  You speak of seconds, but I
>>would be worrying about sub-second precision in my work.
>
> It is a bad idea, and it is physically pointless, given the stabilities
> of the timebases available for computers in general.
>
> Please just take my word as a time-nut, and use a 32.32 binary format
> in seconds (see previous email) and be done with it.
>
> --
> 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.

Right now -- the precision is specified in 'bintime', which is a binary number.
It's not 32.32, it's 32.64 or 64.64 depending on the size of time_t in
the specific platform.
I do not really think it worth to create another structure for
handling time (e.g. struct bintime32), as it will lead to code
duplication for all the basic conversion/math operation. On the other
hand, 32.32 may not be enough in the long future.
What do you think about that?

Thanks,

Davide



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