On 06/15/2017 10:54 AM, Alexander Rast wrote:

See my subsequent message - I'd already tried that and it didn't work, or possibly I'm using the wrong method here. The documentation is unclear where the hosts file should be and how it should be specified in the case of an MPI_Comm_spawn command in the code run by mpiexec. Is the intention that the hosts file should be specified with the mpiexec command (in which case how does it get passed to MPI_Comm_spawn?

The hostfile should be available on the host running mpiexec, and specified with mpiexec -f <hostfile> <...> mpiexec handles the launching of spawned processes in MPICH, so it will have access to the file when needed.

Is this brought in via argv?), or is the intention that the MPI_Comm_spawn command should specify this via an info variable (in which case where should the file reside?

Info is another option that will work. If using info, you can specify a KV pair like: key=hosts value=<list of hostnames> to control the placement. This would need to be specified on all ranks in the comm where MPI_Comm_spawn is called. Ken _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss