Programming/C-Plusplus
From HPC
Contents
Programming Details
C++ is a general-purpose, imperative computer programming language. It is derived from the C language and shares many constructs with it, it also expands into object-orientated programming paradigms.
|
There is direct support for openMP and openMPI. |
Programming example
#include <omp.h>
#include <iostream>
int main ()
{
int thread_number;
#pragma omp parallel private(thread_number)
{
#pragma omp for schedule(static) nowait
for (int i = 0; i < 100; i++)
{
thread_number = omp_get_thread_num();
cout << "Thread " << thread_number << " says " << i << endl;
}
}
return 0;
}
Compilation
The program would be compiled in the following way, optional Intel compiler available too:
[username@login01 ~]$ module add gcc/8.2.0 [username@login01 ~]$ g++ -o test2 -fopenmp test2.c (openMP support) [username@login01 ~]$ ./test2 Thread 22 says 32 Thread 11 says 39 .....
Modules Available
The following modules are available for C
- module add gcc/8.2.0 (GNU compiler)
- module add intel/2018 (Intel compiler)
Note: OpenMP is a library directive within the compiler and does not require any additional module to be loaded.
Usage Examples
Batch example
#!/bin/bash #SBATCH -J openmpi-single-node #SBATCH -N 1 #SBATCH --ntasks-per-node 28 #SBATCH -o %N.%j.%a.out #SBATCH -e %N.%j.%a.err #SBATCH -p compute #SBATCH --exclusive #SBATCH --mail-user= your email address here echo $SLURM_JOB_NODELIST module purge module add gcc/8.2.0 export I_MPI_DEBUG=5 export I_MPI_FABRICS=shm:tmi export I_MPI_FALLBACK=no /home/user/CODE_SAMPLES/OPENMP/demo
[username@login01 ~]$ sbatch demo.job Submitted batch job 234552
Further Information
- https://en.wikipedia.org/wiki/C%2B%2B
- https://en.wikipedia.org/wiki/OpenMP
- http://www.openmp.org/
- https://computing.llnl.gov/tutorials/openMP/