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Message-ID: <3EC93CF2.A03F5C81@ieee.org>
Date: Mon, 19 May 2003 16:22:10 -0400
From: "Pierre A. Humblet" <Pierre DOT Humblet AT ieee DOT org>
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To: Max Bowsher <maxb AT ukf DOT net>
CC: cygwin AT cygwin DOT com
Subject: Re: SPARSE files considered harmful - please revert
References: <Law10-F79o4cWScPAA600033a95 AT hotmail DOT com> <028f01c31e38$0e428c30$78d96f83 AT pomello> <20030519200848 DOT GA246379 AT Worldnet> <02c101c31e3e$7ffdc910$78d96f83 AT pomello>
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Max Bowsher wrote:

> >> Based on the posted numbers, global use of sparse files is a bad idea.
> Can
> >> we conditionalize sparse files on a $CYGWIN option? (Or something else, I
> >> don't mind, but the important thing is that it should not be on by
> default.)
> >
> > Why not make in on by default *when it can help*, i.e. when the write()
> > leaves holes?
> 
> Does anyone know of any programs which write non-sparse files, but not
> contiguously? If there are none, then this approach should be fine.

There must be some... Cygwin would check that the holes are bigger than a
minimum threshold. Thus such files would never be really short and the
penalty for guessing wrong would never be large.
 
> In any case, the $CYGWIN approach could be a valid temporary measure until
> someone writes the heuristic code.

The code change I have in mind is very simple (because it's similar to what is
already done against a Win95 bug), so we might as well skip the intermediate step.
However a patch against current cvs might conflict with bigger changes that 
Chris Faylor has already made in his sandbox.

Pierre

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