Compiling OpenMP Programs

All compilers installed on Brown include OpenMP functionality for C, C++, and Fortran. An OpenMP program is a single process that takes advantage of a multi-core processor and its shared memory to achieve a form of parallel computing called multithreading. It distributes the work of a process over processor cores in a single compute node without the need for MPI communications.

OpenMP programs require including a header file:
Language Header Files
Fortran 77
INCLUDE 'omp_lib.h'
Fortran 90
use omp_lib
Fortran 95
use omp_lib
C
#include <omp.h>
C++
#include <omp.h>

Sample programs illustrate task parallelism of OpenMP:

A sample program illustrates loop-level (data) parallelism of OpenMP:

To load a compiler, enter one of the following:

$ module load intel
$ module load gcc
The following table illustrates how to compile your shared-memory program. Any compiler flags accepted by ifort/icc compilers are compatible with OpenMP.
Language Intel Compiler GNU Compiler
Fortran 77
$ ifort -openmp myprogram.f -o myprogram
$ gfortran -fopenmp myprogram.f -o myprogram
Fortran 90
$ ifort -openmp myprogram.f90 -o myprogram
$ gfortran -fopenmp myprogram.f90 -o myprogram
Fortran 95
$ ifort -openmp myprogram.f90 -o myprogram
$ gfortran -fopenmp myprogram.f95 -o myprogram
C
$ icc -openmp myprogram.c -o myprogram
$ gcc -fopenmp myprogram.c -o myprogram
C++
$ icc -openmp myprogram.cpp -o myprogram
$ g++ -fopenmp myprogram.cpp -o myprogram

The Intel and GNU compilers will not output anything for a successful compilation. Also, the Intel compiler does not recognize the suffix ".f95".

Here is some more documentation from other sources on OpenMP:

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