Difference between revisions of "Programming/C"
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| − | [username@login01 ~]$ module add gcc/ | + | [username@login01 ~]$ module add gcc/8.2.0 |
[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 | ||
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The following modules are available for C | The following modules are available for C | ||
| − | * module add gcc/ | + | * module add gcc/8.2.0 (GNU compiler) |
* module add intel/compiler/64/2016.2.181 (Intel compiler) | * module add intel/compiler/64/2016.2.181 (Intel compiler) | ||
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module purge | module purge | ||
| − | module add gcc/ | + | module add gcc/8.2.0 |
export I_MPI_DEBUG=5 | export I_MPI_DEBUG=5 | ||
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* [http://www.openmp.org/ http://www.openmp.org/] | * [http://www.openmp.org/ http://www.openmp.org/] | ||
* [https://computing.llnl.gov/tutorials/openMP/ https://computing.llnl.gov/tutorials/openMP/] | * [https://computing.llnl.gov/tutorials/openMP/ https://computing.llnl.gov/tutorials/openMP/] | ||
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| − | + | ==Navigation== | |
| − | + | ||
* [[Main_Page|Home]] | * [[Main_Page|Home]] | ||
| − | * [[Applications|Application support]] | + | * [[Applications|Application support]] |
* [[General|General]] | * [[General|General]] | ||
| − | + | * [[Programming|Programming support]] * | |
| − | * [[Programming|Programming support]] | ||
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Revision as of 14:15, 4 June 2019
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#.
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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/8.2.0 [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 add gcc/8.2.0 (GNU compiler)
- module add intel/compiler/64/2016.2.181 (Intel compiler)
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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 $SLURM_JOB_NODELIST module purge module add gcc/8.2.0 export I_MPI_DEBUG=5 export I_MPI_FABRICS=shm:tmi export I_MPI_FALLBACK=no /home/user/CODE_SAMPLES/OPENMP/demo
[username@login01 ~]$ sbatch demo.job Submitted batch job 289552
Further Information
- https://en.wikipedia.org/wiki/C_(programming_language)
- https://en.wikipedia.org/wiki/OpenMP
- http://www.openmp.org/
- https://computing.llnl.gov/tutorials/openMP/