Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!rpi!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.arch
Subject: Re: ATTACK OF KILLER MICROS
Message-ID: <1149@crdos1.crd.ge.COM>
Date: 16 Oct 89 19:12:29 GMT
References: <35825@lll-winken.LLNL.GOV> <1T7kRC#74k11v=eric@snark.uu.net>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: GE Corp R&D Center
Lines: 47


  There's more to supercomputing than scalar speed. One of the primary
things you can do on a supercomputer is run large programs quickly.
Virtual memory is nice, but some programs cause it to thrash. That's
when it's nice to have a real 4GB machine. The same thing can be said
about vector processing, some programs can be done using vector
processors (or lots of parallel processors) faster than scalar.

  I don't see the death of the supercomputer, but a redefinition of
problems needing one. I have more memory on my home computer than all
the computers at this site when I started working here (hell the total
was <2MB). Like wise CPU and even disk. The number of problems which I
can't solve on my home system is a lot smaller than it was back then.


  However, thats the kicker, that real problems are limited in size.
Someone said that the reason for micros catching up is that the
development cost could be spread over the users. For just that reason
the vector processors will stay expensive, because fewer users will need
(ie. buy) them. There will always be a level of hardware needed to solve
problems which are not shared by many users. While every problem has a
scalar portion, many don't need vectors, or even floating point.

  I think this goes for word size, too. When I see that the Intel 586
will have a 64 bit word I fail to generate any excitement. The main
effect will be to break all the programs which assume that short==16
bits (I've ported to the Cray, this *is* a problem). If you tell me I
can have 64 bit ints, excuse me if I don't feel the need to run right
out and place an order. Even as memory gets cheaper I frequently need
1-2 million ints, and having them double in size is not going to help
keep cost down.

  I think that the scalar market will continue to be micros, but I
don't agree with Eric that the demand for supercomputers will vanish,
or that micros will catch them for the class of problems which are
currently being run on supercomputers. The improving scalar performance
will reduce the need for vector processing, and keep them from getting
economies of scale. He may well be right that some of the companies
will fall, since the micros will be able to solve a lot of the problems
which are not massively vectorable or inherently require huge
addressing space.

-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon