Subject: Re: Is SGI O2/150 much faster than PII/233?

From: "M. Nicklaus" <[email-masked]>
Date: Tue, 23 Jun 1998 16:53:51 -0400 (EDT)

On Sat, 20 Jun 1998 23:10:54, Yubo Fan wrote:

> Recently, someone told me that SGI O2/150 workstation could run G94 much
> faster than G94W run on PII/233? Is it true?  Could you please give some
> advice?

I don't have benchmark results for either exactly an SGI O2/150 or for G94W    
run on PII/233.  However, in the context of extensive benchmarking of G94 on  
a range of computers--from Cray J90 to Alpha and Pentium II/Pro systems--
(paper forthcoming in J. Chem. Inf. Comput. Sci.), we have obtained results
for two systems that are close enough that they might allow extrapolation to
the computers you're looking at.

Aggregate job cpu times (sec) for G94 test jobs 1, 28, 94, 155, 194, 296, 302:
SGI Origin 200, R10000 195 MHz CPU, 64 MB RAM:         923 sec
Pentium II 300 MHz CPU, 64 MB RAM, Windows NT:        1283 sec

So I would venture to guess that an SGI O2/150 workstation would run G94
faster than G94W run on PII/233, but not "much faster".  I'd expect on the
order of 50% more CPU time on the PII/233 compared to SGI O2/150.

Hope this helps.

Marc

------------------------------------------------------------------------
 Marc C. Nicklaus                        National Institutes of Health
 E-mail: [email-masked]               Bldg 37, Rm 5B29
 Phone:  (301) 402-3111                  37 Convent Dr, MSC 4255       
 Fax:    (301) 496-5839                  BETHESDA, MD 20892-4255    USA 
      http://rex.nci.nih.gov/RESEARCH/basic/medchem/mcnbio.htm
    Laboratory of Medicinal Chemistry, National Cancer Institute,  &
  Center for Molecular Modeling, Ctr. for Information Technology, NIH
------------------------------------------------------------------------

---

From: Eric Billings <[email-masked]>
Date: Tue, 23 Jun 1998 18:00:08 -0400 (EDT)

Hi Marc -

I recently got an email asking how to build G94 on a Linux box.  Do you
have this handy or could I direct the person to you for some help ?

Thanks,
- Eric

---

From: "Serguei Patchkovskii" <[email-masked]>
Date: Tue, 23 Jun 98 16:49:27 MDT

> order of 50% more CPU time on the PII/233 compared to SGI O2/150.

Sorry, Marc, but this estimation is not valid. R5k is a very different CPU
from R10k. In particular, the R5k was optimized for single precision floating
point. It does not perform well for double precision, which is that Gaussian
is going to excersize. It is also an in-order CPU, and does not tolerate
memory latencies well. The R10k, on the other hand, is super-scalar out-of-
order processor, and has been optimized for double precision floating point.
At the same clock speed, R10k may easily be four times faster for double-
precision floating point than R5k.

The memory substems of O2 and Origin 200 are also very different, and are
designed with different uses in mind. The O2 memory subsystem is not
intended for heavy scientific number crunching (it is optimized for
3D graphics work), and does not perform quite as well for these tasks
as the Origin's memory. 

You can get the detailed technical characteristics of R5k O2 and Origin 200
along with some benchmarks for these machines from the SGI web site at 
http://www.sgi.com if you wish. The basic conclusion is that 150MHz R5k O2
is not going to perform anywhere close to 195 MHz R10k Origin 200 for 
number-crunching programs like Gaussian. If I'll hazard a guess, I would
say that this O2 is going to be at least factor of four slower than this 
particular Origin on direct SCF jobs, with larger factors for more 
memory-intensive jobs (e.g.  MP2). The O2 is definitly NOT going to be 
faster than the PII machine mentioned in your post - simply because it 
is not suited well for the task you are trying to give it.

Regards,

/Serge.P