Xref: utzoo comp.arch:7405 comp.sys.ibm.pc.rt:192
Path: utzoo!utgpu!watmath!clyde!att!rutgers!rochester!pt.cs.cmu.edu!g.gp.cs.cmu.edu!butcher
From: butcher@g.gp.cs.cmu.edu (Lawrence Butcher)
Newsgroups: comp.arch,comp.sys.ibm.pc.rt
Subject: Re: Why the original RT seemed/was slow (was ...)
Summary: Why are our current RT's slow??
Message-ID: <3736@pt.cs.cmu.edu>
Date: 1 Dec 88 03:49:54 GMT
References: <5046@polya.Stanford.EDU> <1287@auschs.UUCP> <1309@auschs.UUCP>
Organization: Carnegie-Mellon University, CS/RI
Lines: 69

Mr. Sauer's benchmark people should be aware that the current version of the
Dhrystone benchmark is version 2.0.  Version 1.1 numbers are not timely.

We have a bunch of RT's.  We use the Metaware High C compiler version 1.4R,
fall back to pcc when mc generates incorrect code, and run MACH.  The
Dhrystone numbers Mr. Sauer quotes are so far from the ones that I measure
here that I wonder if we are measuring different things.  If any reader can
get their RT to run the benchmark significantly faster than I can, please
send me mail.  We would love to know what to do to get a C compiler that
doubles the speed of our programs.

My measured Dhrystone numbers (Dhry 2.0) are (roughly):

2191 for the (RT, ROMP, 6150, Model 025, at 6 MHz) using mc
3176 for the 6152 using mc
3551 for the (APC, 6151, 125, at 10 MHz) using pcc
4474 for the (APC, 6151, 125 at 10 MHz) using mc

The following are my personal feelings only.

The 025, running the software available to me, is about as fast as a SUN 3/50
while running the Dhrystone program.  However my experience is that an 025
machine with 4 megs of RAM, a disk, and MACH, is totally useless.  It cannot
run X10, an xterm, and a single outgoing telnet at the same time.  Yes, I am
saying that it is not as useful as a terminal.  A diskless Sun 3/50 running
SUN OS 3.5, suntools, emacs, and pcc is comfortable.  The 125 is about as
fast as a SUN 3/60, again running the software we have here.  High end 80386
and middle-end 68030 systems should be about twice as fast as the 3/60.

I also have access to a MIPS M500 running at 8 MHz.  It Dhrystones at 12000+.
This number may be hard for others to verify, because I don't think that
MIPS makes 8 MHz chips any more.  The Performance Semi version of the R3000
is available at 16, 20, and 25 MHz.  This chip is commercially available
and there is a C compiler available for it which generates correct code.  Of
course we shouldn't use the the existence of a fast MIPS processor to try to
predict the speed of future IBM machines.  Just the speed of MIPS machines.

I am disappointed that there is no version of GCC for the RT.  IBM could
allocate one person to do a port and give away the results, but it seems
that they would rather have a company sell a compiler without source.

The APA8 display was a joke, and I am disappointed that IBM believes they
fixed things with the APA16 display.  Although both look great on a desk
when they are shut off, both are too small to use for editing.

I am disappointed with the IBM 2-button mouse.  It takes tremendous force
to push the buttons.  We had an informal contest and only one person here
could hold both buttons down while lifting the mouse off the table.  (For
people who have not had the pleasure of using the IBM mouse, you hold both
buttons down at once to emulate holding the middle button down on a real
mouse).

I absolutely cannot believe that the keyboard clicks when you hit the shift
or control key.  I wish that the caps lock key and the control key were the
same size so we could switch the key caps.  Thank you someone for that
layout.  Everyone here rebinds CTRL to the right place.  And the ESC key??

I am disappointed that the RT expansion bus is an AT bus.  The AT form factor
limits the size of peripheral cards, and limits the power they have available.
Ever heard of an SMD controller for the AT??  16 line serial line card??
These problems will be worse with smaller MCA cards.  We will throw away the
RT boxes when they are obsolete.  We will NOT throw away the SUN 3/160 boxes
when the 3/160 is no longer interesting.

Many of the things that I dislike about the RT could be fixed in the future.
Today we give APC's to people who cannot afford SUNs.  We give old RT's to
people to punish them :-)

			Lawrence Butcher @g.gp.cs.cmu.edu
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