Path: utzoo!attcan!uunet!lll-winken!vette!brooks
From: brooks@vette.llnl.gov (Eugene Brooks)
Newsgroups: comp.arch
Subject: Re: 1000000x1000000 Matrix (was: linpack)
Message-ID: <36553@lll-winken.LLNL.GOV>
Date: 23 Oct 89 03:28:13 GMT
References: <9089@batcomputer.tn.cornell.edu> <46500082@uxe.cso.uiuc.edu> <9118@batcomputer.tn.cornell.edu>
Sender: usenet@lll-winken.LLNL.GOV
Reply-To: brooks@maddog.llnl.gov (Eugene Brooks)
Organization: Lawrence Livermore National Laboratory
Lines: 42

In article <9118@batcomputer.tn.cornell.edu> kahn@batcomputer.tn.cornell.edu (Shahin Kahn) writes:
>Like I was going to say in response to Eugene,  you  cant get
>behind the wheels of a Ferarri, go to the school zone, and 
>complain that you cant go faster than 25MPH!
I have never complained about not being able to go faster than 25MPH in a
school zone when driving to work in my 71 Vette.  Last time I checked, my
Vette dusted them thar stiking Italian cars from a stop light.

>If you have lots of scalar code (or code that doesnt run very fast
>on a super), and if it can't be rewritten, all you are doing
>is announcing *your* departure from supercomputers.
The series of supercomputers made by Cray was for some time the fastest you
could get for either scalar or vector coding.  LLNL in fact has preferred them
for their superior scalar and short vector performance.  (These days, of course,
we are not so pure in our decision making.  We prefer Cray machines for their
software compatibility with the Cray-1.  Although we are starting to work on
the problem, we have not fully embraced the notion of portable operating
systems or even standard high level language models.  We use carbon dating
to keep track of some of our dusty decks.) The Cyber 205 could provide more
performance on long vectors, so I guess by your reasoning that you would call
it a supercomputer and accuse anyone buying a Cray machine of departing from
the real supercomputers.  I guess that world has decided to not use enough
REAL SUPERCOMUTERS, because CDC could not sell enough of them to keep the 205
and its children on the market.  Japanese machines blow the doors off the Cray
machines these days (scalar or vector), but CRI is not worried about this.

           Their real nightmares have KILLER MICROS in them.

JUST BECAUSE ONE FRIGGING COMPUTER HAS A HIGHER UPPER BOUND ON THE FLOATING
POINT RATE THAN ANOTHER DOES NOT MEAN THAT IT IS A BETTER COMPUTER, OR THAT
IT IS THE "REAL SUPERCOMPUTER".  THE BOTTOM LINE IS HOW FAST DOES A MACHINE
RUN YOUR APPLICATION.  MY APPLICATION HAPPENS TO FARE POORLY ON SIMD MACHINES
AND HAPPENS TO BE VERY EFFICIENT AND HIGHLY PARALLEL ON MIMD MACHINES WITH
PROCESSORS OPTIMIZED FOR SCALAR PERFORMANCE.  BECAUSE OF THIS I AM ACCUSED
OF DEPARTING FROM SUPERCOMPUTING.  THIS IS GIBBERISH.  IF I FIND A MIMD MACHINE
WITH 100 "KILLER MICROS" COSTING THE SAME AS A YMP AND WHICH RUNS MY APPLICATION
100 TIMES FASTER, I HAVE SIMPLY REDEFINED THE NOTION OF SUPERCOMPUTER.

			   FOR MY APPLICATION


brooks@maddog.llnl.gov, brooks@maddog.uucp