8.9 Environment Variables
8.9.1 MPIRUN_OPTIONS
MPIRUN_OPTIONS is a mechanism for specifying additional command line arguments to mpirun. If this environment variable is set, then any mpirun command will behave as if the arguments in MPIRUN_OPTIONS had been specified on the mpirun command line. For example:
%export
%$MPI_ROOT/bin/mpirun
The above commands are equivalent to the following:
%$MPI_ROOT/bin/mpirun -v -prot -np 2 /path/to/program.x
8.9.2MPIRUN_SYSTEM_OPTIONS
The MPIRUN_SYSTEM_OPTIONS environment variable allows a system administrator to preset options which will be inserted before MPIRUN_OPTIONS and any explicit mpirun options on the command line. This is most useful for establishing a preferred IP address/hostname for TCP communications in the situation where a user explicitly requests TCP via the
8.9.3 MPI_IC_ORDER
The MPI_IC_ORDER environment variable, whose default contents are
"elan:gm:itapi:TCP", instructs
%export MPI_IC_ORDER="elan:TCP:gm:itapi"
%export
%export
%$MPI_ROOT/bin/mpirun
The command line for the above will appear to mpirun as:
$ MPI_ROOT/bin/mpirun -subnet 192.168.1.1 -prot -srun -n4
./a.out
The system interconnect decision will look for the presence of Elan and use it if found. Otherwise, TCP will be used and the communication path will be on the subnet
192.168.1.1.
The following is an example of using TCP over Gigabit Ethernet, assuming Gigabit Ethernet is installed and 192.168.1.1 corresponds to the Ethernet interface with Gigabit Ethernet. Note the implicit use of
%export MPI_IC_ORDER="elan:TCP:gm:itapi"
%export
%$MPI_ROOT/bin/mpirun
8.9.4MPI_PHYSICAL_MEMORY
MPI_PHYSICAL_MEMORY allows you to specify the amount of physical memory in kilobytes available on the system. MPI normally attempts to determine the amount of physical memory