Difference between revisions of "Programming/C"
From HPC
m |
m |
||
| Line 46: | Line 46: | ||
<pre style="background-color: black; color: white; border: 2px solid black; font-family: monospace, sans-serif;"> | <pre style="background-color: black; color: white; border: 2px solid black; font-family: monospace, sans-serif;"> | ||
| − | [username@login01 ~]$ module | + | [username@login01 ~]$ module add gcc/4.9.3 |
[username@login01 ~]$ gcc -o test2 -fopenmp test2.c (openMP support) | [username@login01 ~]$ gcc -o test2 -fopenmp test2.c (openMP support) | ||
[username@login01 ~]$ ./test2 | [username@login01 ~]$ ./test2 | ||
| Line 77: | Line 77: | ||
#SBATCH -N 1 | #SBATCH -N 1 | ||
#SBATCH --ntasks-per-node 28 | #SBATCH --ntasks-per-node 28 | ||
| − | |||
#SBATCH -o %N.%j.%a.out | #SBATCH -o %N.%j.%a.out | ||
#SBATCH -e %N.%j.%a.err | #SBATCH -e %N.%j.%a.err | ||
| Line 86: | Line 85: | ||
module purge | module purge | ||
| − | module | + | module add gcc/4.9.3 |
export I_MPI_DEBUG=5 | export I_MPI_DEBUG=5 | ||
Revision as of 14:45, 7 February 2017
Contents
Programming Details
C is a general-purpose, imperative computer programming language. There are some derivations of the language due to the modernisation of the original specification in the form of C++ and C#.
There is direct support for openMP and openMPI.
Programming example
#include <omp.h>
#include <stdio.h>
int main (int argc, char *argv[]){
int nthreads, tid;
/* Fork a team of threads giving them their own copies of variables*/
#pragma omp parallel
{
/* Obtain thread number */
tid = omp_get_thread_num();
printf("Hello World from thread = %d\n", tid);
/* Only Master thread does this */
if(tid == 0)
{
nthreads = omp_get_num_threads();
printf("Number of threads = %d\n", nthreads);
}
} /* All threads join together and disband */
return (0);
}
Compilation
The program would be compiled in the following way, optional Intel compiler available too:
[username@login01 ~]$ module add gcc/4.9.3 [username@login01 ~]$ gcc -o test2 -fopenmp test2.c (openMP support) [username@login01 ~]$ ./test2 Hello World from thread = 0 Number of threads = 1
Modules Available
The following modules are available for C
- module load gcc/4.9.3 (GNU compiler)
- module load intel/compiler/64/2016.2.181 (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 echo $SLURM_JOB_NODELIST module purge module add gcc/4.9.3 export I_MPI_DEBUG=5 export I_MPI_FABRICS=shm:tmi export I_MPI_FALLBACK=no /home/user/CODE_SAMPLES/OPENMP/demo
[username@login01 ~]$ sbatch demo.job Submitted batch job 289552