Re: Gempak build with PGI compilers

• To: "Neil R. Smith" <neils@xxxxxxxxxxxxxxxxxx>
• Subject: Re: Gempak build with PGI compilers
• From: Robert Mullenax <rmullenax@xxxxxxxxxxxx>
• Date: Sun, 26 Aug 2001 02:04:36 +0000

"Neil R. Smith" wrote:

Neil,

I don't know about the Portland compilers but we built GEMPAK on our Sun
E6500
(12 CPUs) with the Sun FORTE -xparallel option and it ran slower than a
version
compiled with standard optimization.  Which leads to be believe GEMPAK
is not
parallelized.  Can someone confirm or deny this?  Has anyone benefitted
on GEMPAK with multi-CPUs?



> Has anyone had success building the gempak package using the
> Portland group compilers? And on a dual cpu box using the SMP
> options? If so, what were your experiences?
> Thanks, -Neil
>
> ---
> Neil R. Smith, Comp. Sys. Mngr.         neils@xxxxxxxxxxxxxxxxxx
> Dept. Atmospheric Sci., Texas A&M Univ. 979/845-6272

>From owner-ldm-users@xxxxxxxxxxxxxxxx 25 2001 Aug -0700 19:36:56 
Message-ID: <20010826023656.1560.cpmta@xxxxxxxxxxxxxxx>
Date: 25 Aug 2001 19:36:56 -0700
From: stonie.cooper@xxxxxxxxxxxxxxxxx
To: rmullenax@xxxxxxxxxxxx
Subject: Re: Gempak build with PGI compilers
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Robert,

You are correct - gempak is not parallelized (as in HP FORTRAN) or threaded 
(POSIX or otherwise).  Depending on the OS, however, gempak can benefit from 
SMP boxes; in Linux, with fully symetrical mainboards and a kernel compiled for 
SMP, Linux will do _some_ load balancing - even across ipc.  Depending on other 
load variables, your decoders spawned from LDM may be running on one CPU, while 
display programs are running on the other (in a dual cpu situation).

On Sparcs, my experience is that by compiling non-parallelized (non-threaded) 
programs without SMP flags - they run a lot faster.  As Solaris (or HP-UX) 
lends less ability to look "under the hood", I cannot explain why this is the 
case.

Stonie
On Sat, 25 August 2001, Robert Mullenax wrote:

> 
> "Neil R. Smith" wrote:
> 
> Neil,
> 
> I don't know about the Portland compilers but we built GEMPAK on our Sun
> E6500
> (12 CPUs) with the Sun FORTE -xparallel option and it ran slower than a
> version
> compiled with standard optimization.  Which leads to be believe GEMPAK
> is not
> parallelized.  Can someone confirm or deny this?  Has anyone benefitted
> on GEMPAK with multi-CPUs?

Stonie R. Cooper
Science Officer
Planetary Data, Incorporated
3495 Liberty Road
Villa Rica, Georgia  30180
ph. (770) 456-0700

• Follow-Ups:
  • Re: Gempak build with PGI compilers
    • From: Gerry Creager N5JXS