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From: hsv@lanl.gov (Henry S Vaccaro)
Newsgroups: comp.arch
Subject: Re: now 15.8 is almost 27.5???
Summary: IBM RS/6000-530 Dhrystones from 61800 to 82900
Message-ID: <48588@lanl.gov>
Date: 14 Apr 90 14:50:06 GMT
References: <1990Apr4.010757.918@smsc.sony.com> <18191@rpp386.cactus.org> <1990Apr5.215435.8158@ico.isc.com>
Organization: Los Alamos National Laboratory
Lines: 61

In article <1990Apr5.215435.8158@ico.isc.com>, rcd@ico.isc.com (Dick Dunn) writes:
> jfh@rpp386.cactus.org (John F. Haugh II) writes:
> 
> > Apparently Dhrystone 1.1 isn't such a bad benchmark since a recent
> > review of IBM's System/6000 included SPECmark numbers which bear
> > out IBM's performance claims.
> 
> Oh, sure they do...if you can believe that 27.5 is pretty close to 15.8!
> I'd say the SPEC figures absolutely deflate any Dhrystone 1.1 claims.
> 
> The SPECmark for the 20-MHz 6000 is 22.3 x the "ref machine" (VAX 11/780),
> or"22.3 MIPS" in layman's terms.  So even there, a 27.5 MIPS claim is high
> by more than 20%...but that's not the real point.
> 
> *Remember* that Dhrystone is an integer benchmark, and SPEC is 6/10
> floating point.  If, instead, you use the "integer SPEC number", which is
> the geometric mean of the 4 integer SPEC benchmark ratios, the number for
> the 20 MHz 6000 is 15.8 MIPS.  The 27.5 MIPS claim is almost a 75% over-
> statement of the machine's integer performance.
> 
> Make no mistake, the 6000 is still a fast machine, especially so if you're
> using it for a lot of floating point.  But it's just NOT 27.5 integer MIPS
> by any stretch of the imagination.

Well, just which are the right Dhrystone numbers anyway.  Hereere a
few choices for the RS/6000-530:

$ cc -O -U__STR__ -o dhry1-1 dhry1-1.c
$ dhry1-1
Dhrystone(1.1) time for 500000 passes = 8
This machine benchmarks at 61804 dhrystones/second
$
$ cc -O -o dhry1-1 dhry1-1.c
$ dhry1-1
Dhrystone(1.1) time for 500000 passes = 7
This machine benchmarks at 64432 dhrystones/second
$
$ cc -O -Q -o dhry1-1 dhry1-1.c
$ dhry1-1
Dhrystone(1.1) time for 500000 passes = 6
This machine benchmarks at 82918 dhrystones/second
$
(Note: HZ is set to 100 in dhry1-1.c)


I've just finished my own tests on a mostly integer code I use here.
The mackine above is 9-10 times faster than an IBM RT Model 125.  That
machine is roughly "3 MIPS", and runs the code 5-7 times faster than our
old 780 could.  Does this mean that the RS/6000 is 5x9 to 7x10 VUPS?

Another datapoint:  our VAXSTATION 2000's yield:

$ cc -O -o dhry1-1 dhry1-1.c
$ dhry1-1
Dhrystone(1.1) time for 50000 passes = 38
This machine benchmarks at 1311 dhrystones/second
$

Hank Vaccaro
hsv@lanl.gov
rt1!hsv