202405252100
Status: #idea
Tags: DataSpaces

LULESH

OpenMP

• OpenMP is used to run multiple threads on a single processor.
• When compiled without OpenMP support, it is a single-threaded program
• By default, runs with nproc threads

export OMP_NUM_THREADS=4  # Example: Set to 4 threads
./lulesh2.0
unset OMP_NUM_THREADS

OpenMPI

• OpenMPI is used to divide the work across slots which may be spread across multiple machines
• When compiled without OpenMPI support, application is not MPI-aware.
  • Running with mpirun without OpenMPI run does not parallelized the application. Instead all workers will do the same work
• When using mpirun, the pwd for each node is the same. In case the same path does not exist on each node, then the one without the path defaults to the home directory of the user from which we execute the mpirun command
  NEXT STEPS: Run LULESH across the 2 nodes

Bo's Artifact

1. spack unload --all
2. spack install gcc mvapich2

References

1. https://github.com/LLNL/LULESH