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Date: Fri, 19 Dec 2014 20:48:00 +0100
From: Jilles Tjoelker <jilles@stack.nl>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
Subject: Re: Change default VFS timestamp precision?
Message-ID: <20141219194800.GA29107@stack.nl>
References: <201412161348.41219.jhb@freebsd.org>
 <77322.1418933100@critter.freebsd.dk>
 <77371.1418933642@critter.freebsd.dk>
 <7567696.mqJ3jgzJgL@ralph.baldwin.cx>
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Cc: "freebsd-arch@freebsd.org" <arch@freebsd.org>,
 Adrian Chadd <adrian@freebsd.org>
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On Fri, Dec 19, 2014 at 05:41:01PM +0000, Poul-Henning Kamp wrote:
> In message <7567696.mqJ3jgzJgL@ralph.baldwin.cx>, John Baldwin writes:

> >Yes, and multiplication is cheaper than division.  It's not a power of
> >two (so more than a single bitshift), but possibly in the noise compared
> >to the work in bintime() itself.

> But why not use nanosecond resolution given that the cost is cheaper ?

Because there is no API to set timestamps with nanosecond resolution,
and therefore a cp -p copy of a file will appear older than the original
with 99.9% probability. I think that is undesirable.

-- 
Jilles Tjoelker