Q. What is Building and Running MPI Programs?

MPI parallel programs are written using conventional languages such as FORTRAN and C. One or more header files like 'mpi.h' may be needed to provide the necessary definitions and declarations. Similar to any other serial program the programs using MPI require to be compiled first before running the program. The instruction to compile the program may vary according to the compiler being used. If we are employing mpcc compiler then we can compile a C program called 'program.c' employing subsequent command: 

mpcc  program.c -o program.o

Most operations provide command typically named 'mpirun' for spawning MPI processes. It provides facilities for user to select number of processes and what processors they should run on. E.g. to run the object file 'program' as n processes on n processors we use the subsequent command:

mpirun program -np n