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From: eugene@pioneer.arpa (Eugene Miya N.)
Newsgroups: comp.arch
Subject: Re: What with these Vector's anyways? (oh really...)
Message-ID: <2398@ames.UUCP>
Date: Thu, 23-Jul-87 21:57:40 EDT
Article-I.D.: ames.2398
Posted: Thu Jul 23 21:57:40 1987
Date-Received: Sat, 25-Jul-87 11:09:03 EDT
References: <218@astra.necisa.oz> <142700010@tiger.UUCP> <363@astroatc.UUCP> <8344@utzoo.UUCP>
Sender: usenet@ames.UUCP
Reply-To: eugene@pioneer.UUCP (Eugene Miya N.)
Organization: NASA Ames Research Center, Moffett Field, Calif.
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In article <8344@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:
>If a program
>is 90% vectorizable, than magically making the vector part of it *infinitely*
>fast will only speed it up by a factor of ten.  Too many of the pre-Cray
>supercomputers did vectors really fast but were pigs on scalar computation.

How many programs do you know which are 90% vectorizable?  [as opposed
to portions 90% vectorizable.]  {Ref: G. M. Amdahl, SJCC,1967}
Too many?  I am only aware of one which was produced: the STAR-100.
The Cyber 203 came PC: Post-Cray-1.  Everything else could be considered
a paper design.   [^^ A new acronym for people in the know? ;-)]
Pig is not a nice thing to say.

>saying "our machines run your code real fast if you rewrite it somewhat"
>doesn't have nearly the customer appear of saying "our machines run your
>code real fast -- even faster if you rewrite it somewhat".

Surprisingly, people do rewrite; there are over 40 Cyber 205 (The STAR
follow on] sites and people do rewrite for those.  You also have to
distinguish between writing compiler directives and executable code.

From the Rock of Ages Home for Retired Hackers:

--eugene miya
  NASA Ames Research Center
  eugene@ames-aurora.ARPA
  "You trust the `reply' command with all those different mailers out there?"
  "Send mail, avoid follow-ups.  If enough, I'll summarize."
  {hplabs,hao,ihnp4,decwrl,allegra,tektronix,menlo70}!ames!aurora!eugene

I have begun to really learn that the people who say the most know the
least in many cases.