Fast Parallel Stream Compaction for IA-Based Multi/many-core Processors

Stream compaction, frequently found in a large variety of applications, serves as a general primitive that reduces an input stream to a subset containing only the wanted elements so that the follow-on computation can be done efficiently. In this paper, we propose a fast parallel stream compaction for IA-based multi-/many-core processors. Unlike the previously studied algorithms that depend heavily on a black-box parallel scan, we open the black-box in the proposed algorithm and manually tailor it so that both the workload and the memory footprint is significantly reduced. By further eliminating the conditional statements and applying automatic code generation/optimization for performance-critical kernels, the proposed parallel stream compaction achieves high performance in different cases and for various data types across different IA-based multi/manycore platforms. Experimental results on three typical IA-based processors, including a quad-core Core-i7 CPU, a dual-socket 8-core Xeon CPU, and a 61-core Xeon Phi accelerator show that the proposed implementation outperforms the referenced parallel counterpart in the state-of-art library Thrust. On top of the above, we apply it in the random forest based data classifier to show its potential to boost the performance of real-world applications.