Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!bbn!mit-eddie!uw-beaver!rice!sun-spots-request
From: martin@felix.UUCP (Martin McKendry)
Newsgroups: comp.sys.sun
Subject: Sys V sizes, shared libs etc
Message-ID: <80173@felix.UUCP>
Date: 31 Jan 89 06:41:01 GMT
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Original-Date: 20 Jan 89 18:04:44 GMT
X-Sun-Spots-Digest: Volume 7, Issue 127, message 4 of 16

I have a couple of questions about System V implementations and other Unix
systems that implement shared libraries.  Since the answers will reflect
system dependencies, and we are designing for maximum portability, I'd be
interested in answers for any systems, but particularly for the better
known ones -- Suns, 3B2's, Unisys boxes (Convergent?), etc.

     o) What is the maximum size of a process?  Text space and data space.

     o) How many semaphores are allowed?

     o) What tools exist for allocating portions of the address space
	among shared libraries?  How much space is there?

     o) How useful have shared libraries proven in practice for
	implementing complex applications?  Are other techniques or
	combinations of features more useful?

     o) Are semaphores the only appropriate technique for implementing
	mutual exclusion on small objects?  For example, if I had a large
	number (say, 2000) of objects that were small (say, 20 bytes), and
	I wanted to put locks on each object.  Assume that there are many
	processes active in the total structure, but they tend not to
	interfere with one another.  Are semaphores the mechanism of
	choice for this problem?  It seems like a lot of overhead to
	allocate one semaphore per record.

Any answers or input appreciated.

Martin McKendry

--
Martin S. McKendry;    FileNet Corp;	{hplabs,trwrb}!felix!martin