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...?
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