Re: [Boost-users] boost-mpi - Serious performance degradation with OpenMPI 1.10.1

Subject: Re: [Boost-users] boost-mpi - Serious performance degradation with OpenMPI 1.10.1
From: Ilja Honkonen (ilja.honkonen_at_[hidden])
Date: 2016-03-16 01:29:30

Hello
> My project has been using boost’s mpi interface for a number of years
> and have recently encountered a significant performance obstacle moving
> to openmpi 1.10.1. We are seeing a factor of 7-10x slowdown in the
> communication portion of our calculation. Our communication patterns are
> mostly governed by all-to-one reductions and some all-to-all reductions.
> Colleagues who call mpi directly have not seen this behavior.

I've seen similar slowdowns for ptp communication for a long time: 
http://lists.boost.org/boost-users/2015/02/83807.php including with 
other MPI implementations.

If you can use git bisect on https://github.com/open-mpi/ompi to find in 
which commit your slowdown starts that might help a lot. Boost::mpi 
doesn't seem to be developed much nowadays even though there is git 
activity so unless you're transferring very complicated data types I'd 
consider skipping boost::mpi and using MPI directly.

Ilja