Hi everyone, In MPICH, do I have to use mpiexec in the command line, in order to launch a MPI run? I know that in MPI-2 standard, it supports the "dynamic process" feature, i.e., dynamically generate/spawn processes from existing singleton process. So it is not required to use mpiexec/mpirun in the command line, in order to launch a singleton MPI. But, I tried to run without mpiexec in MPICH, but it error out when parsing the arguments in Hydra... Thanks, Jackey