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Date: Wed, 19 Dec 2012 00:29:55 +0100
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: Ian Lepore <freebsd@damnhippie.dyndns.org>
Subject: Re: API explosion (Re: [RFC/RFT] calloutng)
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On Tue, Dec 18, 2012 at 04:27:45PM -0700, Ian Lepore wrote:
> On Tue, 2012-12-18 at 23:58 +0100, Luigi Rizzo wrote:
> > [top posting for readability;
> > in summary we were discussing the new callout API trying to avoid
> > an explosion of methods and arguments while at the same time
> > supporting the old API and the new one]
> > (I am also Cc-ing phk as he might have better insight
> > on the topic).
> > 
> > I think the patch you propose is a step in the right direction,
> > but i still remain concerned by having to pass two bintimes
> > (by reference, but they should really go by value)
> > and one 'ticks' value to all these functions.
> > 
> > I am also dubious that we need a full 128 bits to specify
> > the 'precision': there would be absolutely no loss of functionality
> > if we decided to specify the precision in powers of 2, so a precision
> > 'k' (signed) means 2^k seconds. This way 8 bits are enough to
> > represent any precision we want.

...
> 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 would
> typical to want a 500uS timeout but be willing to late by up to 250uS if

i said k is signed so negative values represent fractions of a
second. 2^-128 is pretty short :)

cheers
luigi