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From: jaw@aurora.UUCP (James A. Woods)
Newsgroups: comp.arch
Subject: Re: Will the real 10 mips machine please stand up?
Message-ID: <914@aurora.UUCP>
Date: Thu, 20-Aug-87 14:37:38 EDT
Article-I.D.: aurora.914
Posted: Thu Aug 20 14:37:38 1987
Date-Received: Sat, 22-Aug-87 11:15:55 EDT
References: <908@aurora.UUCP>
Organization: NASA Ames Research Center, Mt. View, Ca.
Lines: 32

# "Leave the factory, leave the forge, and dance to the new St. George!"
       -- Richard Thompson

Given that no vectorization is involved, picking on the poor
Cray 2 is a bit unfair, I admit.

Just about any junk C code would do as well on a modern RISC board.
It's the old word addressing problem (code for a simple loop like

	while (*s++ == *t++) ;

generates about 20-25 instrunctions), coupled with the abysmal 238 nsec
memory, which only fetches vectors at one 4.1 nsec clock tick per word.

Working over the code to expand chars to ints might help, or getting
the compiler to stick array buffers into register storage would
probably work wonders.

Aside from such desiderata, one new hope for Seymour (for scalar work) is
is the "new improved 2S" with 40% faster RAM (static vs. dynamic).  Until
the "three" comes out, an Amdahl or an NEC would likely be the champ:

Cray X-MP/14      0.94  0.91  0.03	(9.5 ns clock; -hcisl instead of -O)
Cray X-MP/416	  0.84	0.82  0.02	(8.5 ns clock; -hcisl instead of -O)
Amdahl 5890-190   0.54  0.51  0.03	(== half of a model 5890-300 CPU)

Thanks to ucbvax!violet!luzmoor for the X-MP results.
(Bell Labs code 1127 people
might show off their rumored new X-MP C compiler if they dare.)
Also hats off to amdahl!{mat,chuck} for the 5890 figure.

ames!jaw