Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!timbuk!cs.umn.edu!quest!zeno!gene
From: gene@zeno.mn.org (Gene H. Olson)
Newsgroups: comp.arch
Subject: Re: IBM RS6000
Message-ID: <1991Jan14.055922.7546@zeno.mn.org>
Date: 14 Jan 91 05:59:22 GMT
References: <1991Jan10.214122.9506@news.arc.nasa.gov>
Organization: Smartware Consulting
Lines: 37

lamaster@pioneer.arc.nasa.gov (Hugh LaMaster) writes:

>Scientific researchers are beginning to get results on the IBM RS6000 machines.
>(Some RS6000's have apparently been shipping in quantity recently.)
>I heard two comments today, which correspond with other things I have heard.
>These comments are (beware, hearsay coming):

>1)   The machines are as fast as other micros on scalar code, and a lot faster
>     on vector code (other things being equal: clock speed, cache, etc. etc).
>     Many of the codes here *are* vectorizable.

I have one, and only one datapoint.  I wrote a text compression program
(compact) recently posted to comp.sources.misc.  I have run this program
on a wide variety of machines.  Compact has a small main progam loop,
and will use any amount of data memory for the compression tables.  The
main loop fits in the cache of all competitive machines.  However the
data (default working space is about 1 meg) is accessed like a hash table,
so any size cache is hit very hard by data accesses.  Register variables
are used effectively, so stack accesses should be minimal in machines
with 16 or more general purpose registers.

After hearing what a tremendous performer the RS6000 is, I tried running
the program there.  I found it ran dead even (+/- 10%) with a SparcStation
1 (not 1+) and a 25 MHz 486 machine with a good memory subsystem.  All three
of these machines compressed comparable data at 290 to 320 Kbytes/second.

I was quite surprised.  The machine I tested is a bottom-of-the-line
desktop model,  but I was led to believe this machine was 2-to-3 times
faster than the other machines.  The machine is a very early model, and
there could be some performance compromises, although I know of none.
According to a booth IBM guy at Unix Expo, I was running the latest,
greatest, and best version of the operating system and tools.
_________________________________________________________________________
   __ 
  /  )                Gene H. Olson             gene@zeno.mn.org
 / __  _ __  _                             
(__/ _(/_//_(/_                                 gene@digibd.com