Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!husc6!yale!mfci!colwell
From: colwell@mfci.UUCP (Robert Colwell)
Newsgroups: comp.arch
Subject: Re: Don't look back
Message-ID: <665@m3.mfci.UUCP>
Date: 24 Feb 89 03:30:34 GMT
References: <13582@winchester.mips.COM> <20667@lll-winken.LLNL.GOV> <7330@pyr.gatech.EDU> <656@m3.mfci.UUCP> <20821@lll-winken.LLNL.GOV>
Sender: colwell@mfci.UUCP
Reply-To: colwell@mfci.UUCP (Robert Colwell)
Organization: Multiflow Computer Inc., Branford Ct. 06405
Lines: 54

In article <20821@lll-winken.LLNL.GOV> brooks@maddog.llnl.gov.UUCP (Eugene Brooks) writes:
>In article <656@m3.mfci.UUCP> colwell@mfci.UUCP (Robert Colwell) writes:
>>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
>
>Whether or not the Cray-3 is manufacturable, there will certainly be super-
>computers with many gigaflops of VECTOR performance in the near term.  We were
>talking about scalar performance, and not vector performance.  Certain codes

I gathered that, but I was going to just let it slide.  "Vector" 
performance does not necessarily mean "floating point" performance,
and it isn't just floating point that makes supercomputers super.
It's also the other things I mentioned.  I didn't say the micros
will hit a plateau and nothing they ever do thereafter will make
interesting applications run any faster.  I meant that making 
balanced systems is just as important for them as for their costlier
competition, and that users who see high flop numbers on benchmarks
and think it means high commensurately performance on micros may
be in for a bigger than usual shock when they try to use I/O or
fit their application into main memory.

>which are heavily run on Cray machines are scalar and would score high hit
>rates in a rather small cache.  

I guess we could each "prove" our point by judicious selection of
interesting benchmarks.

>I predict that a microprocessor will outrun the
>scalar performance of the Cray-1S within a year.   The "supercomputers" will
>only hold on for those applications which are 99% vectorized, which are darned
>few, and because of this supercomputers will share the computer center floor
>with micro based hardware soon, and on an equal footing.

I hope you mean that there will be some micro somewhere in a system
that achieves a higher throughput on a scalar program, because anything
else doesn't count.  And there, I further predict that said micro,
having achieved this feat, will then have trouble on one of two other
counts -- having enough physical memory present to handle the same
size jobs that people want, having enough flops to not be embarrassing
on more vectorizable codes, and having enough I/O to support all of the
above without making the user smash the keyboard in frustration.  And
all of that at workstation prices.  If you go higher in the cost space,
then your one-chip solution must start competing with multi-chip solutions
that have much more flexibility in their implementation.  And as I've
argued before, they don't pay all that much a penalty for it either, 
because systems at these performance levels put most of the implementation
dollars into memory and I/O, not CPU.

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