Understanding the potential and implications of asymmetric multi-core processors for cluster computing is necessary, as these processors are rapidly becoming mainstream components in??HPC environments. In this paper we evaluate a Linux cluster of Sony PlayStation3 consoles, using microbenchmarks and??bioinformatics applications. We proceed to develop a model and scheduling techniques for effective execution of parallel applications on this low-cost, yet unconventional HPC platform based on the Cell/BE processor. We present an analytical formulation of layered parallelism for clusters of asymmetric multi-core multi-processors and propose new co-scheduling heuristics for effectively executing MPI code with nested task and data parallelism on these systems. Our model has low execution time prediction error and is reliable in predicting optimal mappings of nested parallelism in MPI programs on the PS3 cluster. The presented co-scheduling heuristics reduce slack time on the accelerator cores of the PS3 and improve the performance of MPI applications by 1.7-2.7 times, when compared against the native OS scheduler.