Difference between revisions of "MPI"
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* Attach to process(es) from [[GDB]] | * Attach to process(es) from [[GDB]] | ||
** MPICH-1 runs a background process for each application process: 0, 0b, 1, 1b, ..., therefore, attach to the first ones. | ** MPICH-1 runs a background process for each application process: 0, 0b, 1, 1b, ..., therefore, attach to the first ones. | ||
| + | |||
| + | == Profiling == | ||
| + | [http://www.bsc.es/plantillaA.php?cat_id=488 Paraver] by Barcelona Supercomputing Center is a "a flexible performance visualization and analysis tool" | ||
Revision as of 20:53, 17 November 2011
Contents
Documentation
Implementations
Manual installation
Install in separate subfolder $HOME/SUBDIR, because you may need some MPI implementations (see Libraries)
Tips & Tricks
- For safe consecutive communications create new context, for example:
int communication_operation(MPI_Comm comm) {
MPI_Comm newcomm;
MPI_Comm_dup(comm, &newcomm);
... // work with newcomm
MPI_Comm_free(&newcomm);
}
Mind the overhead of MPI_Comm_dup and MPI_Comm_free.
- If you are having trouble with the multi-homed nature of the HCL Cluster, check here
Debugging
- Add the following code:
int rank;
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (!rank)
getc(stdin);
MPI_Barrier(MPI_COMM_WORLD);
- Compile your code with
-goption - Run parallel application
- Attach to process(es) from GDB
- MPICH-1 runs a background process for each application process: 0, 0b, 1, 1b, ..., therefore, attach to the first ones.
Profiling
Paraver by Barcelona Supercomputing Center is a "a flexible performance visualization and analysis tool"
