Difference between revisions of "Programming/OpenMP"
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* Serializing sections of code | * Serializing sections of code | ||
* Synchronization of work among threads | * Synchronization of work among threads | ||
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| + | == Usage Examples == | ||
| + | |||
| + | <pre style="background-color: #C8C8C8; color: black; border: 2px solid blue; font-family: monospace, sans-serif;"> | ||
| + | #!/bin/bash | ||
| + | |||
| + | #SBATCH -J openmpi-single-node | ||
| + | #SBATCH -N 1 | ||
| + | #SBATCH --ntasks-per-node 28 | ||
| + | #SBATCH -D /home/user/CODE_SAMPLES/OPENMP | ||
| + | #SBATCH -o %N.%j.%a.out | ||
| + | #SBATCH -e %N.%j.%a.err | ||
| + | #SBATCH -p compute | ||
| + | #SBATCH --exclusive | ||
| + | |||
| + | echo $SLURM_JOB_NODELIST | ||
| + | |||
| + | module purge | ||
| + | module load gcc/4.9.3 | ||
| + | |||
| + | export I_MPI_DEBUG=5 | ||
| + | export I_MPI_FABRICS=shm:tmi | ||
| + | export I_MPI_FALLBACK=no | ||
| + | |||
| + | /home/user/CODE_SAMPLES/OPENMP/demo | ||
| + | |||
| + | </pre> | ||
| + | |||
| + | |||
| + | <pre style="background-color: #C8C8C8; color: black; border: 2px solid black; font-family: monospace, sans-serif;"> | ||
| + | [username@login01 ~]$ sbatch demo.job | ||
| + | Submitted batch job 289552 | ||
| + | </pre> | ||
Revision as of 11:11, 30 January 2017
Programming Details
OpenMP is designed for multi-processor/core, shared memory machines. The underlying architecture can be shared memory UMA or NUMA.
It is an Application Program Interface (API) that may be used to explicitly direct multi-threaded, shared memory parallelism. Comprised of three primary API components:
- Compiler Directives
- Runtime Library Routines
- Environment Variables
OpenMP compiler directives are used for various purposes:
- Spawning a parallel region
- Dividing blocks of code among threads
- Distributing loop iterations between threads
- Serializing sections of code
- Synchronization of work among threads
Usage Examples
#!/bin/bash #SBATCH -J openmpi-single-node #SBATCH -N 1 #SBATCH --ntasks-per-node 28 #SBATCH -D /home/user/CODE_SAMPLES/OPENMP #SBATCH -o %N.%j.%a.out #SBATCH -e %N.%j.%a.err #SBATCH -p compute #SBATCH --exclusive echo $SLURM_JOB_NODELIST module purge module load gcc/4.9.3 export I_MPI_DEBUG=5 export I_MPI_FABRICS=shm:tmi export I_MPI_FALLBACK=no /home/user/CODE_SAMPLES/OPENMP/demo
[username@login01 ~]$ sbatch demo.job Submitted batch job 289552