Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!bellcore!dduck!johno
From: johno@dduck.ctt.bellcore.com (John OBrien)
Newsgroups: comp.sys.sequent
Subject: Re: What?  I'm confused. Sequent their strengths & weaknesses
Message-ID: <17595@bellcore.bellcore.com>
Date: 11 Sep 89 13:00:25 GMT
References: <1263@syma.sussex.ac.uk> <1309@syma.sussex.ac.uk> <218@runxtsa.runx.oz> <17580@bellcore.bellcore.com> <5053@eos.UUCP>
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Reply-To: johno@dduck.UUCP (John OBrien)
Organization: The Joe Irby Bar and Grill
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In article <5053@eos.UUCP> eugene@eos.UUCP (Eugene Miya) writes:

>>The sequent architecture does automatic multiprocessing
>across the available processors.
>>The "Parallel Processing" is not done automatically!
>
>Oh?      What's the difference?  [*if you think this terminology is bad,
>I can refer you to other vendors with bad terminology...*]

A reasonable question.  Here's the definition I've been using to explain
the terms "multi-processing" and "parallel-processing."  They've worked
well in the context of my talks, papers, etc.  Of course, they can
be generalized to death if you like.

"multi-processing" occurs when several processors within the same architecture
are running different, loosely coupled processes or programs.  These
programs/processes are NOT closely related to each other, although they may
communicate with each other via IPC or shared memory or such.

"Parallel Processing" is the decomposition of a single program or process
into several smaller, tightly coupled processes.  These are closely related
and use more sophisticated techniques for IPC such as spin locks, barrier
setting etc.

As stated above, either of these definitions can be extended to cover the
other if you please.  I show a picture with these definitions to clear
up any ambiguity in my meaning.  The multi-processing one shows several
processes running disjoint on several processors.  The parallel processing
one shows a large program being broken up, run, and then being put back
together.



John O'B


John J. O'Brien
ISCP (Integrated SCP)
ctt!johno or johno@ctt
RRC 4B-307
699-8788