mpirun ERROR : No PMIx server was reachable

Question

When I use mpirun to run the osu_bw , it errors ,here is my log:

$ which mpirun
/data/software/install/oneapi/mpi/latest/bin/mpirun
# I'm using Intel MPI

$ mpirun -np 2 ./osu_bw
No PMIx server was reachable, but a PMI1/2 was detected.
If srun is being used to launch application,  2 singletons will be started.
This test requires exactly two processes
This test requires exactly two processes

When I use Open MPI 5.0.1 to run osu_bw , it succeeded , here is my log:

$ which mpirun
/data/software/install/openmpi/5.0.1/bin/mpirun

$ mpirun -np 2 --host node1,node2 ./osu_bw
# OSU MPI Bandwidth Test v5.7.1
# Size      Bandwidth (MB/s)
1                       0.03
2                       0.08
4                       0.14
8                       0.29
16                      0.50
32                      1.02
64                      1.75
128                     3.99
256                     7.32
512                    12.71
1024                   26.13
2048                   54.45
4096                   97.07
8192                  179.59
16384                 259.69
32768                 342.69
65536                 414.06
131072                541.21
262144                564.08
524288                600.48
1048576               597.75
2097152               604.22
4194304               540.85

Answer 1

Going off of @Gilles's comment: IntelMPI and OpenMPI are not ABI compatible presently. If you built with one of them and used the other, it will not work.

The MPICH family is ABI compatible with each other (MPICH, MVAPICH, IntelMPI, etc.)., but not with OpenMPI, and vice-versa.

On a side note, the MPI Forum IS working on bridging this gap, but that's still a work in progress :P