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From: brianu@ada-uts.UUCP
Newsgroups: net.arch
Subject: Re: 128Mb - I give up!
Message-ID: <7900002@ada-uts.UUCP>
Date: Mon, 9-Dec-85 11:04:00 EST
Article-I.D.: ada-uts.7900002
Posted: Mon Dec  9 11:04:00 1985
Date-Received: Fri, 13-Dec-85 07:29:50 EST
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Nf-From: ada-uts!brianu    Dec  9 11:04:00 1985


>Meanwhile, vector setup time on the Cray is always short and predictable
>even for data that is not contiguous and (with the X/MP) even for gather
>scatters.
>J. Giles
>Los Alamos
>----------
Well, not exactly.  While I agree that the vector setup time on a Cray
XMP is always short, it is not always predictable.  Due to the
indeterminate nature of the memory conflicts between XMP processors,
the setup times can vary, not to mention that gather scatters can
interfere with themselves.  I think the XMP hardware manual states that
the setup is unpredictable; I know the instructors at Cray Software
Training did.
   By the way, Cray Research did a marketing survey and asked their
customers if they prefered large amounts of slightly slower memory or
somewhat less faster memory.  The consensus (reflected in the Cray 2)
was for more memory.

Brian Utterback
Intermetrics Inc.
733 Concord Ave. Cambridge MA. 02138. (617) 661-1840
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