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Subject: Re: Multiple CPUs in SUN environment
Author: John Swanson
Date: 1999-01-15 15:01:00

CPU time in a parallel environment is a shaky concept. Some machines
sum the time spent in all threads, other processors return just the time
in the
primary thread, others seem to return random numbers.
The valid measure is the wall clock time, but be sure you have an
empty
machine in making wall clock measurements, because you are measuring the
time for all the active tasks. Wall clock time is physical time, the
time you
have to get your coffee, lunch, sleep, or vacation before you can look
at your
results.
John.Swanson

> -----Original Message-----
> From: Geno Vallejos [SMTP:gvalle@c...]
> Sent: Friday, January 15, 1999 12:02 PM
> To: xansys@o...
> Subject: [xansys] Multiple CPU's in SUN environment

> From: Geno Vallejos

> To all my fellow ANSYS users:

> I have had some interesting results when solving the same structural
> problem using the same model but on two different SUN machines.
> Below are the specifics;

> The structural model is a part created in ProENGINEER 18
> I am using ANSYS ProFEA 5.4 and ProENGINEER 18.

> Solution #1:
> Machine: SUN E-3000 server
> Processors: 4 each 360 MHz CPU's
> Operating System: Solaris 2.6
> CP Time (from the file.lst summary) = 10 minutes 28 seconds

> The first time I requested four CPU's using the config.ans file, with
> the
> following line added;
> NUM_PROC = 4
> The config.ans file was located in the /docu directory.
> The file.lst indicated that 4 CPU's will be used

> The second time I requested four CPU's using a .inp file. The .inp
> file had
> the following line;
> /config,nproc,4

> The solution times (CP Time listed above) was 10 minutes 28 seconds

> Solution #2:
> Machine: SUN Ultra 60 workstation
> Processors: 1 each 360 MHz CPU
> Operating System: Solaris 2.6
> CP Time (from the file.lst summary) = 10 minutes 53 seconds

> Can anyone help explain why the E-3000 server and the Ultra 60
> workstation solved the structural analysis problem by taking the same
> amount of time????

> I have heard some ideas....but nothing concrete. Some here at ATL say
> that the four SUN processors will work as hard as they need to to
> solve
> the problem. I say that I would like them to solve the problem as
> fast as
> possible. Observing the CPU activity bar during the solution phase
> indicated that at no time were any of the four CPU's working any
> higher
> than 40-50% of maximum capacity. Was this due to some SUN or Solaris
> setting "chocking" the CPU speed or efficiency; or some ANSYS setting
> not getting the full support of multi-tasking from the SUN server??

> Thanks in advance!

> Geno Vallejos
> ATL Ultrasound - A Philips Company
> Bothell, Washington 98021
> www.atl.com

Posts possibly associated with message #266AuthorDateScore
247Multiple CPUs in SUN environmentGeno Vallejos gvalle@1999/01/15 
248Re: Multiple CPUs in SUN environmentBrian Breaux1999/01/15 
250Re: Multiple CPUs in SUN environmentJoe Metrisin1999/01/15 
260Re: Multiple CPUs in SUN environmentBrian Murphy1999/01/15 
266Re: Multiple CPUs in SUN environmentJohn Swanson1999/01/15 
269Re: Multiple CPUs in SUN environmentPatrick Tibbits1999/01/15 
270Re: Multiple CPUs in SUN environmentHeinz.Hempowitz@1999/01/15 
281Re: Multiple CPUs in SUN environmentDan Bohlen1999/01/16 
283Re: Multiple CPUs in SUN environmentJohn Swanson1999/01/16 
323Summary of Multiple CPUs in SUN environment questionGeno Vallejos gvalle@1999/01/19 
324Re: Summary of Multiple CPUs in SUN environment queChristopher Wright1970/01/01 
332Re: Summary of Multiple CPUs in SUN environment questionJoe Rasche1999/01/20 
340Re: Summary of Multiple CPUs in SUN environment questionBrian Murphy1999/01/20