Difference between revisions of "Parallel job submission"
From ScientificComputing
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== Shared memory job (OpenMP) == | == Shared memory job (OpenMP) == | ||
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| − | + | <tr valign=top> | |
| − | * | + | <td style="width: 35%; background: white;"> |
| + | <br> | ||
| + | [[Image:shared_memory_computing.png|300px]] | ||
| + | <br> | ||
| + | </td> | ||
| + | <td style="width: 60%; background: white;"> | ||
| + | * In shared-memory parallel computing, multiple processors (or "threads") perform tasks independently but share a common global memory. If a processor modified an array in the memory, all other processors can see this update as well | ||
| + | * A serial code can be parallelized by marking code sections, which should be run in parallel, with [https://www.openmp.org/ openMP directives]. | ||
| + | * An openMP code can run on a single compute node and use up to maximum number of processors in that compute node, e.g., 24, 36, or 128 processors. | ||
| + | * To run an openMP code, define number of processors(threads) in $OMP_NUM_THREADS | ||
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| + | $ export OMP_NUM_THREADS=8 | ||
| + | $ bsub -n 8 ./program | ||
| + | </td> | ||
| + | </tr> | ||
| + | </table> | ||
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== Distributed memory job (MPI) == | == Distributed memory job (MPI) == | ||
| − | * | + | <table> |
| − | * | + | <tr valign=top> |
| − | + | <td style="width: 35%; background: white;"> | |
| + | <br> | ||
| + | [[Image:distributed_memory_computing.png|300px]] | ||
| + | <br> | ||
| + | </td> | ||
| + | <td style="width: 60%; background: white;"> | ||
| + | * In distributed-memory parallel computing, multiple processors (or "cores") perform tasks independently while each processor possesses its own private memory resource. If a processor modify an array in its memory, this processor has to communicate to other processors so that the others see this update. | ||
| + | * Massage Passing Interface (MPI) library implements distributed memory parallel computing which can be programmed in C, C++ and Fortran | ||
| + | * An MPI program can run on a single compute node as well as on multiple compute nodes | ||
| + | * An MPI program must be launched using "mpirun" | ||
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| + | $ module load gcc/6.3.0 openmpi/4.0.2 | ||
| + | $ bsub -n 240 mpirun ./program | ||
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| − | + | </td> | |
| − | + | </tr> | |
| − | + | </table> | |
== Example == | == Example == | ||
Revision as of 14:27, 3 June 2021
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$ export OMP_NUM_THREADS=8 $ bsub -n 8 ./program |
Distributed memory job (MPI)
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$ module load gcc/6.3.0 openmpi/4.0.2 $ bsub -n 240 mpirun ./program
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Example
$ export OMP_NUM_THREADS=8 $ bsub -n 8 ./hello_omp Generic job. Job <8147290> is submitted to queue <normal.4h>.
$ unset OMP_NUM_THREADS $ bsub -n 240 mpirun ./hello_mpi MPI job. Your environment is not configured for MPI. Please load the module(s) needed by your job before executing 'bsub'. Request aborted by esub. Job not submitted.
$ module load intel open_mpi $ bsub -n 240 mpirun ./hello_mpi MPI job. Job <8147303> is submitted to queue <normal.4h>.
