High Performance Computing (HPC) is nearing the exascale era and several challenges have to be addressed in terms of application development. Future parallel programming models should not only help developers take full advantage of the underlying machine but they should also account for highly dynamic runtime conditions, including frequent hardware failures. In this paper, we analyze the porting process of a plasma confinement simulator from a traditional MPI+OpenMP approach to a parallel objects based model like Charm++. The main driver for this effort is the existence of load imbalanced input scenarios that through pure OpenMP scheduling cannot be solved. By using Charm++ adaptive runtime and integrated balancing strategies, we were able to increase total CPU usage from 45.2% to 80.2%, achieving a 1.64× acceleration, after load balancing, over the MPI+OpenMP implementation on a specific input scenario. Checkpointing was added to the simulator thanks to the pack-unpack interface implemented by Charm++, providing scientists with fault tolerance and split execution capabilities.
