From: Andrew Apted <ajapted AT netspace DOT net DOT au>
Date: Sat, 16 Sep 2000 14:03:47 +1000
To: djgpp AT delorie DOT com
Subject: Re: Malloc bug in DJGPP V2.03
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In-Reply-To: <8pl56t$3v2$1@nets3.rz.RWTH-Aachen.DE>; from broeker@physik.rwth-aachen.de on Tue, Sep 12, 2000 at 11:48:45AM +0000
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Hans-Bernhard Broeker writes:

>  Andrew Apted <ajapted AT netspace DOT net DOT au> wrote:
>  > I'm experiencing a problem with my DJGPP program (glBSP, a nodes
>  > builder for DOOM) where it runs out of memory under DOS, even though
>  > there should be plenty left.  I've memory-profiled the code (under
>  > Linux), and the most it ever uses (not including overheads) is 9 MB,
>  > yet my machine has 64 MB RAM.  This is with DJGPP V2.03.
>  
>  The strategy you use to do the allocation is prone of causing heap
>  fragmentation at an enormous rate. Using realloc() to increase memory
>  block sizes in as small steps as you do it leaves back a huge trail of
>  small-size blocks that are not available to be reused for larger
>  blocks, later.

OK, I can understand that, and I'll be fixing my source to improve the
situation (using realloc in large steps would help, right ?), though I
don't understand why my program works fine under Linux (same machine)
and Win32 (similiar machine) but fails under DOS/DJGPP.  I suspect
that DJGPP's malloc could be improved to cope with certain allocation
limitations in DPMIs (like CWSDPMI, as I mentioned before changing its
internal heap parameter affects how far the testmem program gets),
unfortunately I don't have the time to work on it.

Cheers,
__
\/   Andrew Apted  <ajapted AT users DOT sourceforge DOT net>