In this paper we describe techniques for compiling fine-grained SPMD-threaded programs, expressed in programming models such as OpenCL or CUDA, to multicore execution platforms. Programs developed for manycore processors typically express finer thread-level parallelism than is appropriate for multicore platforms. We describe options for implementing fine-grained threading in software, and find that reasonable restrictions on the synchronization model enable significant optimizations and performance improvements over a baseline approach. We evaluate these techniques in a production-level compiler and runtime for the CUDA programming model targeting modern CPUs. Applications tested with our tool often showed performance parity with the compiled C version of the application for single-thread performance. With modest coarse-grained multithreading typical of today's CPU architectures, an average of 3.4x speedup on 4 processors was observed across the test applications.

@inproceedings{stratton:10:mcuda_cgo,
title={Efficient compilation of fine-grained SPMD-threaded programs for multicore {CPU}s},
author={Stratton, John A. and Grover, Vinod and Marathe, Jaydeep and Aarts, Bastiaan and Murphy, Mike and Hu, Ziang and Hwu, Wen-mei W.},
booktitle={Proceedings of the 8th annual IEEE/ACM international symposium on Code generation and optimization},
pages={111--119},
year={2010},
organization={ACM}
}