While the default options are often adequate, the recommendations of this section may help mpich make better use of the specific facilities provided by these systems.
Mpich can be run on a heterogeneous network of workstations of various kinds. For simple collections of workstations, the mpirun command can be used; more complex collections of heterogeneous machines require a p4 ``procgroup file'' (for the ch_p4 device) or a ``RSL file'' (for the globus2 device). The format of the ``procgroup'' file is described in Section Special Considerations for Running on a Network of Workstations . The format of ``RSL files'' can be found in the Globus documentation found at http://www.globus.org under the Resource Specification Language.
The ch_p4 device is most easily used when all workstations share a common file system. MPI executables should reside in the shared file system. However, a shared file system is not necessary. By using the ``procgroup'' file, the location of the executable on each workstation can be specified as a different location.
configureSome SGI systems support both 32 and 64 bit pointers (addresses). Mpich uses the architecture IRIX to refer to 32 bit systems and IRIX64 for 64 bit systems. Mpich will attempt to detect the appropriate architecture automatically, but you can force a choice by specifying the architecture with the configure options --with-arch=IRIX, --with-arch=IRIXN32, --with-arch=IRIX32, or --with-arch=IRIX64. The last three of these correspond to the SGI compiler options -n32, -32, and -64. Make sure to attach the flags to the compilers and linker using environment variables as follows:
setenv CC "cc -64" setenv FC "f77 -64" configure ...