You want to use the "sequential" mapper and then specify each proc's location, like this for your hostfile:
host1 host1 host2 host2 host3 host3 host1 host2 host3 and then add "--mca rmaps seq" to your mpirun cmd line. Ralph On Dec 21, 2020, at 5:22 AM, Vineet Soni via users <users@lists.open-mpi.org <mailto:users@lists.open-mpi.org> > wrote: Hello, I'm having touble using the MPMD hostfile in which I want to place 2 executables on the same nodes. For example, I can do this using Intel MPI by: $ mpirun -machine host-file -n 6 ./EXE1 : -n 3 ./EXE2 $ cat host-file host1:2 host2:2 host3:2 host1:1 host2:1 host3:1 This would place 2 MPI processes of EXE1 and 1 MPI process of EXE2 on host1. However, I get an error if I define the same hostname twice in the hostfile of OpenMPI: $ mpirun -hostfile host-file -np 6 ./EXE1 : -np 3 ./EXE2 $ cat host-file host1 slots=2 max_slots=3 host2 slots=2 max_slots=3 host3 slots=2 max_slots=3 host1 slots=1 max_slots=3 host2 slots=1 max_slots=3 host3 slots=1 max_slots=3 Is there a way to place both executables on the same hosts using a hostfile? Thanks in advance. Best, Vineet
