From:	Endlisnis <s257m AT unb DOT ca>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: question to malloc and free
Date:	Fri, 28 Aug 1998 11:27:20 -0300
Organization:	NBTel Internet
Lines:	27
Message-ID:	<35E6BE48.62C42B67@unb.ca>
References:	<m0zCOH2-000S4fC AT inti DOT gov DOT ar>
NNTP-Posting-Host:	fctnts06c09.nbnet.nb.ca
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Salvador Eduardo Tropea (SET) wrote:
> >     I've read that the size of the block allocated by malloc/new is always
> > a power of 2, and rounded up to one if it isn't (after adding it's few
> > words).  Why does it do this?  This seems (to me) like it would waste about
> > 1/2 the RAM allocated.
> First: DJ did a new malloc included in v2.02 to solve it.
> Now: You waste some *virtual memory* not physical so normally doesn't affect.
> The reason malloc works in this way is because is *fast*, the blocks are
> clasified by size, only 32 sizes and to satisfy a malloc request you just
> need to check if one block is available (in linked list of blocks of this
> size) or create a new one, no "heap walks" are needed (like in Borland's
> malloc).
> Of course there are better solutions like the one used by DJ in the last
> malloc.
	That's a neat idea.  I noticed that malloc/new/free/delete was really fast in
DJGPP.  I used it for an assignment that tried to show how it was faster to
use a circular array for a queue rather than a linked list.  The only problem
was that under DJGPP, it was FASTER to use a linked list.  My professor didn't
believe me, I had to show him the executable before he would give me marks for
the assignment.
-- 
     (\/) Endlisnis (\/)
          s257m AT unb DOT ca
          Endlisnis AT GeoCities DOT com
          Endlis AT nbnet DOT nb DOT ca

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