Subject: Pentium Pro vs. Pentium II

From: "Peter R. Schreiner" <[email-masked]>
Date: Tue, 23 Sep 1997 15:17:49 +0200 (MET)

Dear CCLers,

The question

"Does anyone have experience with numerical applications
(Ab initio codes etc.) on Pentium Pro vs. Pentium II under Linux systems?"

triggered quite a number of useful responses. It looks like
PCs are finally replacing average type workstations. It is still
not clear whether or not the Pentium II series really
is better that the Pentium Pros - at least they are different
in price.

Here are the responses:

You can find some timings concerning PC GAMESS benchmarks on Pentium Pro and
Pentium II systems under Windows NT on the URLs:

http://classic.chem.msu.su/gran/gamess/index.html
http://classic.chem.msu.su/gran/gamess/performance.html

May be these can somewhat help to estimate performance under Linux.

Regards,

    Alex. A. Granovsky
    Moscow State University

-----------------------------------------------------------
[email-masked]

%%%%%%%%%

I am really interested in any informations you will receive.
My personal experience, up to now, is only with the Pro 256kb cache.
I used it to run DFT programs, and the performance, with big systems
(30 atoms or more) are excellent. It is 85% of an IBM rs6000 Mod. 3CT
with 1MB of L2 cache memory. And it costs roughly 20%. Remarkable!

As for the PII, I have no experience. Anyhow, I "think" that the Pro
even if the clock is slower, should perform better. The L2 cache in
the Pro is fully integrated on the processor and thus run at the
same speed of the processor itself.  On the PII, instead, the
the L2 memory runs at 1/2 of the speed of the processor.

Finally, the Pro is somewhat cheaper than the PII 266 MHz.

Hope it helps,

Best regards

Luigi

Luigi Cavallo
Dept. of Chemistry
Univ. of Naples, ITALY
Email [email-masked]

%%%%%%%%%%

While I don't have any timings or benchmarks for Pentium II systems,
I suggest you have a look at http://www.specbench.org/ for SPECint95 and
SPECfp95 results.  From what I've seen the pentium II is much better in
floating point and better in integer than the pentium pro.

Also direct your web browser at
http://www.intel.com/procs/perf/PentiumII/spec95int.htm
and
http://www.intel.com/procs/perf/PentiumII/cpumark32.htm
and
http://www.intel.com/procs/perf/PentiumII/nortonsi32.htm

To the bottom of this email I've attached the output of cpu benchmarks I ran on
a dual PPRO 200 (the fact that it is dual means nothing; the SMP code for Linux
is bad right now and the benchmarks are not multithreading).

good luck,
Rich

BBBBBB   YYY   Y  TTTTTTT  EEEEEEE
BBB   B  YYY   Y    TTT    EEE
BBB   B  YYY   Y    TTT    EEE
BBBBBB    YYY Y     TTT    EEEEEEE
BBB   B    YYY      TTT    EEE
BBB   B    YYY      TTT    EEE
BBBBBB     YYY      TTT    EEEEEEE

BYTEmark (tm) Native Mode Benchmark ver. 2 (10/95)
NUMERIC SORT    :  Iterations/sec.:         70.24  Index:   1.80
STRING SORT     :  Iterations/sec.:          4.35  Index:   1.94
BITFIELD        :  Iterations/sec.:   16976692.52  Index:   2.91
FP EMULATION    :  Iterations/sec.:          3.90  Index:   1.87
FOURIER         :  Iterations/sec.:       1393.26  Index:   1.58
ASSIGNMENT      :  Iterations/sec.:          0.71  Index:   2.71
IDEA            :  Iterations/sec.:        138.29  Index:   2.12
HUFFMAN         :  Iterations/sec.:         63.19  Index:   1.75
NEURAL NET      :  Iterations/sec.:          0.71  Index:   1.13
LU DECOMPOSITION:  Iterations/sec.:         52.81  Index:   2.74
 ...done...
===========OVERALL=============
INTEGER INDEX:           2.119
FLOATING-POINT INDEX:    1.700
 (90 MHz Dell Pentium = 1.000)
===============================

%%%%%%%%%%%%%%

  I don't have any real quantitative answers for you, but thought I might
pass along my experience with running Gaussian 94 under Linux on a single
Pentium Pro 200MHz with 64MB RAM and a fast/wide SCSI hard drive.  The
couple of runs that I did to compare the speed with an Indigo2 (single
R8000 75MHz processor) seemed to give a factor of about 3-4 in cpu time.
That is, the Pentium Pro 200 was 3-4 times slower than the SGI.  Considering
the relative costs this is pretty good in my opinion.  I compiled Gaussian94
using f2c/gcc.  I sometimes wonder if Gaussian would run faster if compiled
with a good commercial fortran compiler (e.g. Absoft).  But even the
educational price ($524.25 US) is too pricey for me right now.

  My guess is that you will not see much of an improvement with the Pentium II
for these types of floating point intensive calculations.  I believe that
most of the advantage of the Pentium II comes from MMX capabilities which
you will find useless with Linux.  At least this is what I recall reading
in Linux Journal or Unix Review.  Floating point is probably only marginally
faster than a Pentium Pro.

      Hope this helps - John Bushnell      [email-masked]

%%%%%%%%%%%%%%

We are implementing a system called LoBoS, short for Lots of Boxes on
Shelves, which consists of 64 dual Pentium Pro machines.  We organize them
to do supercomputing with molecular dynamics calculations.  We tested the
Pentium Pro and the Pentium II prior to selecting the Pentium Pro.

1. The Pentium Pro gives equivalent performance.  Our benchmark which
   consists of extensive floating point (CHARMM) took 2 hours on a 200
   MHz Pentium Pro.  On a 266 MHz Pentium II the time was 2 hours times
   (200/266).

This is not surprising since a PentiumII is a Pentium Pro core with the
MMX instructions added on.  MMX, which is entirely integer operations,
doesn't do anything for floating point operations.  It might do something
for pointer references and integer math but compilers do not currently use
MMX for these operations.

The PentiumII has some new features.  One which improves performance is
better IO to the system bus.  However, this is essentially offset by the
fact that the L2 cache runs at half the CPU speed.  Essentially we saw a
wash between these two design changes.

Buy the Pentium Pro !  It gives you MUCH more for the money.

Eric Billings
LoBoS Project
NIH

%%%%%%%%%%%%

I tested calculations using Gaussian 94, Revision D.4

1. #N b3p86/gen 5d freq : ClO2 calculation using 79 basis
  Pentium Pro 200MHz : 256 mins
  Pentium II  233MHz : 192 mins
  CrayT3E (DEC Alpha EV5.6 450MHz, 900MFLOPS, not parallelized) : 39 mins

2. #N b3p86/gen 5d opt=z-matrix : Cl2O calculation using 131 basis
  Pentium     133MHz : 336 mins
  Pentium Pro 200MHz : 149 mins
  Pentium II  233MHz : 130 mins
  CrayT3E (DEC Alpha EV5.6 450MHz, 900MFLOPS, not parallelized) : 56 mins

-----------------------------------------------------------------------
Son, Sang-kil                   [email-masked]     \\____//
                                                               (. .) |
Quantum Chemistry Laboratory                                   | " | |
Dept. of Chemistry, KAIST, South Korea                       CC|___/CCC
                        http://cmsrisc.kaist.ac.kr/qclab/        U
-----------------------------------------------------------------------

 ...Peter

-- 

    ////
___|--00___________________________________________________________________
   C   ^     Dr. Peter R. Schreiner
    \ ~/     Institut fuer Organische Chemie
    <><>     Georg-August Universitaet Goettingen
             Tammannstr. 2                    Phone: +49-(0)551-393287
             D-37077 Goettingen, Germany      FAX:   +49-(0)551-399475
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