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From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: dynamic memory allocation
Date: 1997/06/16
Message-ID: <33A55F1B.63FE@gsfc.nasa.gov>#1/1
X-Deja-AN: 248851209
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Reply-To: Stephen.Leake@gsfc.nasa.gov
Newsgroups: comp.lang.ada
Date: 1997-06-16T00:00:00+00:00
List-Id: <comp.lang.ada>


I'm trying to convince my project that dynamic memory allocation is a
bad idea in an embedded software system (a satellite control system, in
this case). 

They are proposing a message passing scheme where sending tasks allocate
buffers for each message from a heap, and receiving tasks deallocate. I
have suggested that the heap could become fragmented (the buffers are
NOT all the same size). They say "we'll just test it thoroughly".

Can anyone provide a reference to a book or study article that says this
is bad? To me it seems obvious, and the general tone in this newsgroup
is that it's obvious. I have a couple books on realtime embedded design,
and they don't even bother to mention dynamic allocation -
unfortunately, that makes it hard to say "see, this book says it's bad".

On the other side, are there any discussions of how to test such a
system, to show that it does not become fragmented? Or a book on
designing dynamic memory allocation algorithms to avoid fragmentation?

Thanks for any help,

-- 
- Stephe