Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!sun!pitstop!sundc!seismo!uunet!mfci!colwell
From: colwell@mfci.UUCP (Robert Colwell)
Newsgroups: comp.arch
Subject: Re: Don't look back
Message-ID: <656@m3.mfci.UUCP>
Date: 22 Feb 89 13:46:32 GMT
References: <13582@winchester.mips.COM> <20667@lll-winken.LLNL.GOV> <7330@pyr.gatech.EDU>
Sender: colwell@mfci.UUCP
Reply-To: colwell@mfci.UUCP (Robert Colwell)
Organization: Multiflow Computer Inc., Branford Ct. 06405
Lines: 42

In article <7330@pyr.gatech.EDU> mccalpin@loligo.cc.fsu.edu (John McCalpin) writes:
>In article <20667@lll-winken.LLNL.GOV>
>                 brooks@maddog.llnl.gov (Eugene Brooks) writes:
>>In article <13582@winchester.mips.COM> mash@mips.COM (John Mashey) writes:
>>A long, and well founded, analysis of why superminis are being squeezed out
>>of their performance niche from the rear by VLSI based machines.
>>
>I don't mean to pick on CDC/ETA --- even the fastest Cray's are going
>to get caught by the highest performance RISC chips pretty soon.

A note from the other side of the aisle.  "Even the fastest Crays"?  Are
you kidding?  If you believe the Cray-3 is going to be manufacturable
(an entertaining discussion all by itself) then how the heck do you think
a micro is going to get 1800 mflops any time soon?  I think that's wishful
thinking or outright fantasy.  Do you realize how many bits you'd be 
stuffing into its pins per unit time?  Or maybe you think you're going to
make the micro out of GaAs?  You still have to feed it.  Cray has the
wire lengths down below 1" to maintain this kind of data rate.  I don't
think you're going to touch that kind of computation rate without the same
big bucks the big boys must spend.  Are you going to do CMOS with 100K ECL
I/O's?  Or do you think you're going to get there with TTL switching levels?

And those large machines put way more than half their money into their
memory subsystems.  What sleight of hand will make it possible for the 
micros to do better?  And if they don't do better, then their systems
won't cost significantly less than the less integrated machines, in which
case their cost advantage dissipates.  The same goes for the I/O needed
to support all the flops being predicted willy-nilly in this stream of
discussion.  The cost/performance of I/O isn't increasing at anything 
near the rate of the CPUs.  So my (possibly broken) crystal ball says
that the default future isn't so much a world filled with satisfied
customers of nothing but micros so much as one filled with CPUs spending
an awful lot of time waiting on badly mismatched memory and I/O systems.

Data caches aren't going to help you much, either, running the kinds of
codes that Crays are good for.  Name a data cache size, and every user
will say it's too small.

Bob Colwell               ..!uunet!mfci!colwell
Multiflow Computer     or colwell@multiflow.com
175 N. Main St.
Branford, CT 06405     203-488-6090