Re: Speed is the one true performance metric

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Article #12719

#12719

From: Garry Wiegand
Date: Mon, 17 Nov 1986 02:56

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In article <3576@utcsri.UUCP>, greg@utcsri.UUCP (Gregory Smith) writes:
> This is silly. Broken computers don't give wrong answers. They crash,
> or they log soft errors, or they act flaky. It is almost impossible to
> imagine a hardware fault that would have no visible effect other than
> to make the 'value' (whatever it may be) of the output wrong.

Can't help donating my favorite horror story: there's a Vax upstairs that 
once upon a time a little trouble with some very involved computations. 
After telling the user in question, for a couple weeks, to fix his program, 
we decided to investigate. Diagnostics ran fine. After much elaborate head-
scratching, we happened to ask it to plot out a nice sine curve. The curve
looked fine too - except for a spike or two. Our jaws dropped. We 
checked that plotting program five ways from Sunday, and it was OK. We 
pulled the FP card and the drop-outs vanished.

The machine was only two years old, so I guess that puts an upper bound on 
how long it had been giving wrong answers. :-)

garry wiegand   (garry%cadif-oak@cu-arpa.cs.cornell.edu)

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Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!rochester!cornell!batcomputer!garry
From: garry@batcomputer.tn.cornell.edu (Garry Wiegand)
Newsgroups: comp.arch
Subject: Re: Speed is the one true performance metric
Message-ID: <1510@batcomputer.tn.cornell.edu>
Date: Sun, 16-Nov-86 21:56:06 EST
Article-I.D.: batcompu.1510
Posted: Sun Nov 16 21:56:06 1986
Date-Received: Mon, 17-Nov-86 04:56:22 EST
Reply-To: garry%cadif-oak@cu-arpa.cs.cornell.edu
Organization: Cornell Engineering && Flying Moose Graphics
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