Parallelizing more loops with compiler guided refactoring
Paper in proceedings, 2012

The performance of many parallel applications relies not on instruction-level parallelism but on loop-level parallelism. Unfortunately, automatic parallelization of loops is a fragile process, many different obstacles affect or prevent it in practice. To address this predicament we developed an interactive compilation feedback system that guides programmers in iteratively modifying their application source code. This helps leverage the compiler's ability to generate loop-parallel code. We employ our system to modify two sequential benchmarks dealing with image processing and edge detection, resulting in scalable parallelized code that runs up to 8.3 times faster on an eight-core Intel Xeon 5570 system and up to 12.5 times faster on a quad-core IBM POWER6 system. Benchmark performance varies significantly between the systems. This suggests that semi-automatic parallelization should be combined with target-specific optimizations. Furthermore, comparing the first benchmark to manually-parallelized, hand-optimized pthreads and OpenMP versions, we find that code generated using our approach typically outperforms the pthreads code (within 93-339%). It also performs competitively against the OpenMP code (within 75-111%). The second benchmark outperforms manually-parallelized and optimized OpenMP code (within 109-242%).

Refactoring

Compiler Feedback

Automatic Loop Parallelization

Author

P Larsen

Technical University of Denmark (DTU)

R. Ladelsky

IBM Haifa Labs

Jacob Lidman

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

Sally A McKee

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

S Karlsson

Technical University of Denmark (DTU)

A. Zaks

Intel Development Center, Israel

Proceedings of the International Conference on Parallel Processing. 41st International Conference on Parallel Processing, ICPP 2012, Pittsburgh, PA, 10 - 13 September 2012

0190-3918 (ISSN)

410-419

Subject Categories

Computer and Information Science

DOI

10.1109/ICPP.2012.48

ISBN

978-076954796-1

More information

Latest update

2/28/2018