Parallel space saving onmulti- and many-core processors

摘要

Given an array A of n elements and a value 2 ≤ k ≤ n, a frequent item or k-majority element is an element occurring inmore than n∕k times. The k-majority problem requires finding all of the k-majority elements. In this paper, we deal with parallel shared-memory algorithms for frequent items;wepresent ashared-memoryversionof theSpace Saving algorithm,andwe study itsbehavior with regard to accuracy and performance on many and multi-core processors, including the Intel Phi accelerator.We also investigate a hybrid MPI/OpenMPversion against a pure MPI-based version. Through extensive experimental results, we prove that the MPI/OpenMP parallel version of the algorithm significantly enhances the performance of the earlier pure MPI version of the same algorithm. Results also prove that for this algorithm the Intel Phi accelerator does not introduce any improvement with respect to the Xeon octa–core processor.