Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!garnett
From: garnett@cs.utexas.edu (John William Garnett)
Newsgroups: comp.sys.next
Subject: Re: NeXTSTation benchmark
Summary: quoted RS/6000 numbers misleading
Keywords: toy benchmark MFLOPS
Message-ID: <59@lion.cs.utexas.edu>
Date: 16 Nov 90 07:06:10 GMT
References: <742@kaos.MATH.UCLA.EDU>
Followup-To: comp.benchmarks
Distribution: na
Organization: UT at Austin, Dept. of CS
Lines: 63

In article <742@kaos.MATH.UCLA.EDU> barry@pico.math.ucla.edu (Barry Merriman) writes:
>So, here's a quick comparison, compiling my little million multiply C
>program with ``gcc -O'' in all cases (= ``cc -O'' on NeXTs)

First of all so that we all know what's being talked about -
here again is the million (actually 999,999) multiply benchmark source.


#include <stdio.h>

main()
{
	int i;
	float x;
	float m;
	x=1.0000; 
	m=1.00001;

	for (i=1;i<1000000;i++) {x *= m;}

	printf("x = %f \n",x);
	exit(0);
}

>
>Also, we have a special guest appearance by the...RS/6000!
>First, this editorial comment:
>Ralph Seguin writes:
>
>>The RS/6000s SCREAM.  I have been using them for quite some
>>time now.  They give SPECmarks which kill every other machine at that price
>>level.
>
>okay, but...
>
>IBM RS/6000 (scalar) (Thanks to Charles Purcell---I don't know if this was gcc, though)
>
>  3.3 MFLOPS

For the program in question, this number of 3.3 appears to be in the right ballpark.
I ran the program and received a number of 3.57.  HOWEVER, if you make one small
change to the program, it performs at 6.25 (toy) MFLOPS.  This change is merely
to change all occurences of "float" to "double".  If the loop limit is increased
from 1,000,000 to 10,000,000, this number jumps to 6.49 (startup costs are
amortized).  Obviously IBM optimized the machine toward better performance on
doubles.

Note that all of these numbers were generated using IBM's C Compiler with -O
on the RS/6000 Model 320 which is rated at approx 7.5 "real" MFLOPS.

>
>So, for simple scalar floating point, the NeXTStation seems to be the
>price/performance leader (and even the performance leader!)
>

These are big claims to make based on a 10 line benchmark :-).

Followups via email, comp.unix.aix, or comp.benchmarks.
-- 
John Garnett
                              University of Texas at Austin
garnett@cs.utexas.edu         Department of Computer Science
                              Austin, Texas