Jeff,
Thanks for your reply.
I inquired the same of PGI. Dave Borer, PGI Customer Service Manager,
responded:
I believe -fast and -fastsse are identical for 64-bit compilers,
but there are some differences
with 32-bit compilers. I don't think TCP/IP based MPI routines have
better performance from
optimizations, unless the processes are all running on the same
machine. I will ask engineering
how messages are passed when all the processes are running on the
same hardware.
I am running on a 64-bit machine; I used -fast.
Larry Baker
US Geological Survey
650-329-5608
ba...@usgs.gov
On 19 May 2011, at 6:21 PM, Jeff Squyres wrote:
On May 18, 2011, at 8:32 PM, Larry Baker wrote:
The PGI compilers have a -fast and a -fastsse option. Does OpenMPI
make effective/safe use of SSE instructions (block moves maybe?)?
Not really. The biggest thing that we do that can take advantage of
vector instructions is memcpy, *mostly* in the shared memory
transport, but also if your MPI application hap some funky non-
contiguous MPI datatypes, too.
On their web site, PGI uses -fast in their examples for OpenMPI
rather than -fastsse. I don't know why.
Maybe for more portability...?
--
Jeff Squyres
jsquy...@cisco.com
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/
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