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Subject: Re: [OMPI users] Question about OpenMPI performance vs. MVAPICH2
From: Brian Powell (powellb_at_[hidden])
Date: 2009-09-21 02:27:26


Jed Brown wrote:
> Are you saying the output of mpicc/mpif90 -show has the same
> optimization flags? MPICH2 usually puts it's own optimization flags
> into the wrappers.

Jed, thank you for your reply. Yes, mpif90 shows (other than differing
libraries) identical flags.

Ralph Castain wrote:
> Did you set -mca mpi_paffinity_alone 1? This will bind the processes
> to cores and (usually) significantly improve performance.

Ralph, thank you for the suggestion. I had focussed on RDMA, and this
made a significant difference. I have only had time to re-run an
ensemble of one configuration (rather than the suite I had been
running) and it improved the OpenMPI performance by 19.5%. So, it
would appear this was the primary cause.

I will read through the documentation to find how to make this the
default.

Thank you for your assistance! I look forward to the 1.3.4 improvements.

Cheers,
Brian