Porting irregular reductions on heterogeneous CPU-GPU configurations

Heterogeneous architectures are playing a significant role in High Performance Computing (HPC) today, with the popularity of accelerators like the GPUs, and the new trend towards the integration of CPUs and GPUs. Developing applications that can effectively use these architectures is a major challenge. In this paper, we focus on one of the dwarfs in the Berkeley view on parallel computing, which are the irregular applications arising from unstructured grids. We consider the problem of executing these reductions on heterogeneous architectures comprising a multi-core CPU and a GPU. We have developed a Multi-level Partitioning Framework, which has the following features: (1) it supports GPU execution of irregular reductions even when the dataset size exceeds the size of the device memory, (2) it can enable pipelining of partitioning performed on the CPU, and the computations on the GPU, and (3) it supports dynamic distribution of work between the multi-core CPU and the GPU. Our extensive evaluation using two different irregular applications demonstrates the effectiveness of our approach.