[MITgcm-devel] [MITgcm-cvs] MITgcm/tools/build_options CVS Commit

[David Ferreira]

Dimitri,
My reasoning was more or less the opposite of yours: with -xSSE4.2, if 
someone
makes the mistake of submitting to queue "normal", he will get an error 
message
and realize there is an issue. BTW, the message is not really criptic, 
(+documented on
the NAS webpage+comments in the optfile):

Fatal Error: This program was not built to run on the processor
in your system. The allowed processors are: Intel(R) processors
with SSE4.2 and POPCNT instructions support.

With xSSE4.1 by default, most people would not realize they could benefit
from running on normal_N with xSSE4.2 (and in my case I noticed a 
significant
speed up, I can't remember exactly how much though !).
Is it not the case for you ?
david



On 4/9/10 2:07 PM, Art Lazanoff wrote:
> a few additional notes:
>
> ifort v11.1 supports -xSSE4.1 and -xHost but not earlier compilers.
>
> Use of -xHost is interesting if and only the code is to be run on the 
> same processor family (harpertown or nehalem, etc) as the code is 
> compiled on. -xHost retrieves the CPUs feature set if possible. The 
> Pleiades front-ends are currently Harpertown. One solution is to run a 
> PBS job to compile the code.
>
> At the moment, NAS PBS offers Harpertown queues (-q normal) and a 
> Nehalem queue (-q normal_N). The next assortment of nodes is due to 
> arrive in a few weeks and these are Westmeres. We'll likely have 
> another queue forthese.
>
> So, Dimitris, the answer to your question from earlier today about 
> which CPUs you ran on can be determine by which queue you submitted 
> the job to.
>
> Sincerely,
>
> Art
>
> ***************************************************************************** 
>
> Art Lazanoff                                     NASA Ames Research 
> Center
> Senior Scientific Consultant                       Mail Stop 258-6
> Arthur.S.Lazanoff at nasa.gov (650) 604-1687        Moffett Field, CA 
> 94035-1000
> ***************************************************************************** 
>
>
> --------------------------------------------------
> From: "Menemenlis, Dimitris (3248)" <Dimitris.Menemenlis at jpl.nasa.gov>
> Sent: Friday, April 09, 2010 10:51 AM
> To: <mitgcm-devel at mitgcm.org>
> Cc: "Lazanoff, Arthur S. (ARC-AFS)[COMPUTER SCIENCES CORPORATION]" 
> <arthur.s.lazanoff at nasa.gov>
> Subject: [MITgcm-devel] [MITgcm-cvs] MITgcm/tools/build_options 
> CVS     Commit
>
>> David, can I make SSE4.1 the default in linux_ia64_ifort+mpi_ice_nas
>> with a comment that 4.2 and 4.3 is also available on some of the 
>> newer processors.
>>
>> 4.1 is the lowest common denominator.  That way new pleiades users,
>> e.g., Pierre Rampal, don't end up with cryptic error messages when
>> they try to use the default optfile.
>>
>> Also, according to Art Lazanoff, there is probably not much speed
>> up to be expected from 4.2 and 4.3 over 4.1.
>>
>> Let me know, Dimitris
>>
>>
>
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel