MPI

This section will describe how to perform analysis of an MPI application.

Profiling an MPI application

If you want to profile an MPI application MALT will dump a profile for each process so each rank. But by default the files will be named with the PID of the process which is not what you expect in this particular case.

In order to get the rank, you first need to prepare a wrapper to replace the PID by the rank.

Notice it should be redone avery time you use a different MPI flavor.

# using mpicxx
malt --prep-mpi

# if you use another mpi C++ compiler
malt --prep-mpi my_mpi_cxx_compiler

Then when launching your mpi application :

mpirun -np 16 malt --mpi ./my_program

Filter do dump only some ranks

In MPI you might know that some ranks are behaving exactly the same way. In this case you can dump only a set of them :

mpirun -np 16 malt --mpi -o filter:ranks=0,5-8,10 ./my_program