Paper Info
Title
A practical approach to DOACROSS parallelization
Abstract
Loops with cross-iteration dependences (doacross loops) often contain significant amounts of parallelism that can potentially be exploited on modern manycore processors. However, most production-strength compilers focus their automatic parallelization efforts on doall loops, and consider doacross parallelism to be impractical due to the space inefficiencies and the synchronization overheads of past approaches. This paper presents a novel and practical approach to automatically parallelizing doacross loops for execution on manycore-SMP systems. We introduce a compiler-and-runtime optimization called dependence folding that bounds the number of synchronization variables allocated per worker thread (processor core) to be at most the maximum depth of a loop nest being considered for automatic parallelization. Our approach has been implemented in a development version of the IBM XL Fortran V13.1 commercial parallelizing compiler and runtime system. For four benchmarks where automatic doall parallelization was largely ineffective (speedups of under 2×), our implementation delivered speedups of 6.5×, 9.0×, 17.3×, and 17.5× on a 32-core IBM Power7 SMP system, thereby showing that doacross parallelization can be a valuable technique to complement doall parallelization.
Year
DOI
Venue
2012
10.1007/978-3-642-32820-6_23
Euro-Par
Field
DocType
Volume
Synchronization,IBM,Computer science,Parallel computing,Fortran,Thread (computing),Compiler,Multi-core processor,Automatic parallelization,Distributed computing,Runtime system
Conference
7484
ISSN
Citations 
PageRank 
0302-9743
4
0.42
References 
Authors
11
6
Name
Order
Citations
PageRank
Priya Unnikrishnan120014.67
Jun Shirako243334.56
Kit Barton343.80
Sanjay Chatterjee4614.41
Raul Silvera517910.74
Vivek Sarkar64318409.41