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From: littauer@amdahl.amdahl.com (Tom Littauer)
Newsgroups: comp.arch
Subject: Re: What with these Vector's anyways?
Message-ID: <10956@amdahl.amdahl.com>
Date: Mon, 27-Jul-87 21:36:38 EDT
Article-I.D.: amdahl.10956
Posted: Mon Jul 27 21:36:38 1987
Date-Received: Wed, 29-Jul-87 01:20:10 EDT
References: <218@astra.necisa.oz> <142700010@tiger.UUCP> <363@astroatc.UUCP> <8344@utzoo.UUCP> <3636@well.UUCP>
Reply-To: littauer@amdahl.UUCP (Tom Littauer)
Organization: Amdahl Corp, Sunnyvale CA
Lines: 31

In article <3636@well.UUCP> rchrd@well.UUCP (Richard Friedman) writes:
>The best supercomputers are fast scalar machines first, with vector
>processing hardware for additional speedup.  Machines like the Cray X-MP
>have a vector-to-scalar speedup factor of about 10.  But their scalar
>performance is faster than any conventional machine.  
                !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If the Dhrystone benchmarks are to be believed, this isn't the case.
The May '87 report shows Cray X-MP at 18,530, and the IBM 3090-200
at 31,250. I'd mention our (much faster) machines, but that'd get
perilously close to advertising :-).

Nevertheless, the basic point is valid. If you could get it, you'd
want a machine fast enough to do EVERYTHING quickly, not just a
subset of things. This is not to demean the Cray machines: they do
vectorizable work very quickly, but not all work is vectorizable.

Until compilers are clever enough to make multithread/vector work
out of work the programmer thinks of as serial, we're just gonna
have to pick the right tool for the task at hand.

End of pontification.
-- 
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