Live Webcast 15th Annual Charm++ Workshop

To minimize data movement, state-of-the-art parallel sorting algorithms use techniques based on sampling and histogramming to partition keys prior to redistribution. Sampling enables partitioning to be done using a representative subset of the keys, while histogramming enables evaluation and iterative improvement of a given partition. We introduce Histogram sort with sampling (HSS), which combines sampling and iterative histogramming to find highquality partitions with minimal data movement and high practical performance. Compared to the best known (recently introduced) algorithm for finding these partitions, our algorithm requires a factor of Θ(log(p)/log log(p)) less communication, and substantially less when compared to standard variants of Sample sort and Histogram sort. We provide a distributed-memory implementation of the proposed algorithm, compare its performance to two existing implementations, and provide a brief application study showing benefit of the new algorithm.