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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.arch
Subject: Re: Transputer and occam
Message-ID: <5393@utzoo.UUCP>
Date: Mon, 1-Apr-85 16:18:46 EST
Article-I.D.: utzoo.5393
Posted: Mon Apr  1 16:18:46 1985
Date-Received: Mon, 1-Apr-85 16:18:46 EST
References: <825@ucbtopaz.CC.Berkeley.ARPA> <811@loral.UUCP>
Organization: U of Toronto Zoology
Lines: 18

> >I'm a little dubious about the value of hypercubes, as most big
> >programs have a 5% to 20% purely serial component.
> >(Note: this only applies to general-purpose
> >machines.  Obviously, certain problems can have the serial part reduced
> >to a tiny fraction.)
> 
> Have you any data to support this claim?

There is one very large piece of supporting data:  CDC's incredibly
expensive failure, the Star-100 supercomputer, which ran vectors very
quickly and scalars very slowly.  They had hoped for automatic vectorizers
that would be good enough to make the thing work, and had also hoped that
most problems would vectorize simply and almost completely.  No such luck.
One of the reasons the Cray-1 was such a success, by comparison, was that
the Cray does scalar operations at blazing speed too.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry