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Mail Archives: djgpp/2002/04/13/12:30:26.1

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From: CBFalconer <cbfalconer AT yahoo DOT com>
Organization: Ched Research
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Newsgroups: comp.os.msdos.djgpp
Subject: Re: New DJGPP hogs memory (was: I need help)
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Date: Sat, 13 Apr 2002 16:14:59 GMT
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

CBFalconer wrote:
> Eli Zaretskii wrote:
> >
> > > From: CBFalconer <cbfalconer AT yahoo DOT com>
> > > Newsgroups: comp.os.msdos.djgpp
> > > Date: Fri, 12 Apr 2002 22:17:04 GMT
> > >
> > > First, nmalloc seems to have had no faults shown up with this.  It
> > > appears to handle this continuous realloc about 2 to 4 times
> > > faster, and to use less memory in the aggregate. Note that
> > > evilalgo segfaulted with an input parameter of 45000, while
> > > nmalloc lets it handle at least 100000 without squealing (with my
> > > memory constraints).
> >
> > The segfaults are not the important factor here, and might even hide
> > the actual performance issue (memory efficiency) from view: the
> > program crashes because it doesn't test the pointer returned by
> > realloc before dereferencing it.
> >
> > It is much better to modify the code slightly to test whether realloc
> > returns NULL, and if so, print the iteration count (and/or the amount
> > of memory it succeeded to allocate) and exit.  Then you'd have a more
> > accurate quantitative measure of the memory overhead enforced by the
> > kind of ridiculously bad reallocation code such as the one used by
> > this program.
> 
> I did that.  I started from someones evil code, just as a test.
> See the version in
> 
>    <http://cbfalconer.home.att.net/download/hashlib.zip>
> 
> Compare the times when it doesn't segfault for the previous
> article.

URL correction:

    <http://cbfalconer.home.att.net/download/nmalloc.zip>

-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT worldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!


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