Homogeneous Networks.

The easiest way is to edit the file mpich/util/machines/machines.xxxx, to contain names of machines of architecture xxxx. The xxxx matches the arch given when mpich was configured. Then whenever mpirun is executed, the required munber of hosts will be selcted from this file for the run. (There is no fancy scheduling; the hosts are selected starting from the top). To run all` your MPI processes on a single workstation, just make all the lines in the file the same.