Difference between revisions of "Programming/C"
From HPC
m |
m |
||
Line 3: | Line 3: | ||
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#. | 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#. | ||
{| | {| | ||
− | |style="width:5%; border-width: 0" | [[File:icon_tick.png]] | + | |style="width:5%; border-width: 0;cellpadding="0"" | [[File:icon_tick.png]] |
− | |style="width:95%; border-width: 0" | There is direct support for [[programming/OpenMP|openMP]] and [[programming/OpenMPI|openMPI]]. | + | |style="width:95%; border-width: 0;cellpadding="0"" | There is direct support for [[programming/OpenMP|openMP]] and [[programming/OpenMPI|openMPI]]. |
|- | |- | ||
|} | |} |
Revision as of 10:51, 3 March 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 add gcc/4.9.3 (GNU compiler)
- module add 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