Path: utzoo!utgpu!watmath!iuvax!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!uxe.cso.uiuc.edu!mcdonald
From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.arch
Subject: Re: linpack
Message-ID: <46500082@uxe.cso.uiuc.edu>
Date: 20 Oct 89 14:57:00 GMT
References: <9089@batcomputer.tn.cornell.edu>
Lines: 21
Nf-ID: #R:batcomputer.tn.cornell.edu:9089:uxe.cso.uiuc.edu:46500082:000:991
Nf-From: uxe.cso.uiuc.edu!mcdonald    Oct 20 09:57:00 1989



>Well, I'll through in my $0.02 of disagreement with this thread.  It
>has been my experience that the poor performance of the LINPACK
>100x100 test on supercomputers is *entirely typical* of what users
>actually run on the things. There a plenty of applications burning up
>Cray, Cyber 205, and ETA-10 cycles which have average vector lengths
>*shorter* than the average of 66 elements for the LINPACK test, and
>which are furthermore loaded down with scalar code.

>The 100x100 test case is not representative of *everyone's* jobs, but
>it is not an unreasonable "average" case, either.  I think it is much
>more representative of what most users will see than the 1000x1000
>case, for example.  The 1000x1000 case is a very good indicator of

I heartily agree with that: I have two projects that I tried on 
a big supercomputer: one diagonalized zillions of 20x20 matrices,
the other wants to diagonalize a single 1000000x1000000 matrix.
Neither was suitable for a Cray!

Doug McDonald