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From: eugene@nas.nasa.gov (Eugene N. Miya)
Newsgroups: comp.sys.super
Subject: Re: MPP
Message-ID: <1991Jun27.165415.24978@nas.nasa.gov>
Date: 27 Jun 91 16:54:15 GMT
References: <1991Jun24.172633.5978@nas.nasa.gov> <1991Jun26.140913.1238@Arco.COM> <1991Jun26.184744.16948@convex.com>
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Organization: NAS Program, NASA Ames Research Center, Moffett Field, CA
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In article <1991Jun26.184744.16948@convex.com> patrick@convex.COM
(Patrick F. McGehearty) writes:
>Will most super applications be rewritten to make them more adaptable
>to massive parallelism?  
>or
>Will special hand crafting for each target architecture continue to be
>needed to any kind of reasonable performance from MPP systems?
>
>If the applications will be rewritten, how long will it be before
>the revised versions are available?  [Chicken and egg problem here:
>without machines and language features, where is the motivation to
>rewrite?  Without applications, where is the motivation to provide
>the machines and language features?]

It is interesting that you did not get much response.  You should get
60% of your responses in 24 hours.

I think a lot of sites reel when they change machines.  I am porting
two codes right now for which the -cfc option isn't helping.  Subtle semantic
problems.

Will apps. be re-written?  Probably, but only enough to adapt them to
one more architecture (at a time).  The purpose (as you know) is to run
the code, not to adapt it to every conceiveable computer.

Special hand crafting?  That's the tension.  The attraction is speed.
If you are not using it, then by some people's definition, "that's not
efficient."  You have the chicken-egg analogy down pat.  A CM code
won't run on a hypercube nor a shared-memory machine without modification.
Frequently extensive mods.

I think what will drive this will be academic competitiveness.  A prof
some where will go assign a grad student some CM or cube time, then
come up with some new algorithm, for solving saying a problem.
Colleagues will rush in and use it.  THEY will have to make decisions
what existing codes to drop.  Some codes, very large, will be declared National
resources, say like NASTRAN, and big efforts will be made to port those
codes.  The rest will fad away, perhaps to run on older, little-used
machines sitting in corners, single CPU killer micros to older Crays

I don't think you can put a technology based time frame on it.
It will happen when a new advance in a field takes place.  It will
probably rendered graphically (we can guess this).  We will see hype
articles on events which will motivate colleagues to rush and get
similar machines, maybe a vendor will get a brief burst of orders.
Meanwhile we have to get vendors together and achieve consensus on language
features.  We may literally have to get vendors running each other's
codes to get consistent language features.  We also have to encourage
applications users to come up with more small benchmarks, consensus
again, which vendors can use as test cases.  We teeth with toys.  We must.
In the time it takes some vendors to port a test application, a company
may go out of business.  That scares a lot of people because that is
time wasted.

Notables missing from the Trade Show:
	IBM
	Thinking Machines
	Others

--eugene miya, NASA Ames Research Center, eugene@orville.nas.nasa.gov
  Resident Cynic, Rock of Ages Home for Retired Hackers
  {uunet,mailrus,other gateways}!ames!eugene