Which version of MPI? mpiexec or mpirun ?

Question

Hi,
I am quite new to MPI, and i would like to know which version is installed on my computer.
I know it exists MPI-1, MPI-2 and MPI-3.
Which version does Fenics use / is recommended for Fenics?

Are

mpiexec --version

and

mpirun --version

the good syntax for what i am searching?

And, besides, which command is recommended (for a fenics calculation of course) ?

mpiexec  -n NP python program_name.py

or

mpirun -np NP python program_name.py

Both synatx run my fenics code correctly.

Thanks.

Answer 1

If you google "mpirun vs mpiexec" you will find many answers regarding their similarities/differences.

For FEniCS, I do not believe it matters. If you have concerns, note that the FEniCS book uses the following syntax:

mpirun -n <#> python program_name.py

(the -n and -np flags are synonyms of each other; it makes no difference what you use)