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Subject: Re: [OMPI users] Question about OpenMPI performance vs. MVAPICH2
From: Jed Brown (jed_at_[hidden])
Date: 2009-09-20 11:50:23

Brian Powell wrote:
> I ran a final test which I find very strange: I ran the same test case
> on 1 cpu. The MVAPICH2 case was 23% faster!?!? This makes little sense
> to me. Both are using ifort as the mpif90 compiler using *identical*
> optimization flags, etc. I don't understand how the results could be
> different.

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.