MPICH vs OpenMPI

Question

Can someone elaborate the differences between the OpenMPI and MPICH implementations of MPI ? Which of the two is a better implementation ?

Answer 1

in my opinion if you do development rather than production system, go with mpich. mpich has built-in debugger, while openmpi does not last time I checked.

In production openmpi most likely will be faster. But then you may want to research other alternatives, such as Intel mpi.

Answer 2

I concur with the previous poster. Try both to see which one your application runs faster on then use it for production. They are both standards compliant. If it is your desktop either is fine. OpenMPI comes out of the box on Macbooks, and MPICH seems to be more Linux/Valgrind friendly. It is between you and your toolchain.

If it is a production cluster you need to do more extensive benchmarking to make sure it is optimized to your network topology. Configuring it on a production cluster will be the main difference in terms of your time as you will have to RTFM.

Answer 3

Both are standards compliant, so it shouldn't matter which you use from a correctness point of view. Unless there is some feature, such as specific debug extensions, that you need, then benchmark both and pick whichever is faster for your apps on your hardware. Also consider that there are other MPI implementations that might give better performance or compatibility, such as MVAPICH (can have the best infiniband performance) or intel MPI (widely supported ISVs). HP worked hard to get their MPI qualified with lots of ISV codes too, but I'm not sure how it is faring after being sold on to Platform...