Wavesched: A Novel Scheduling Technique For Control-flow Behavioral Descriptions

In this paper, we present a novel scheduling algorithm targeted towards minimizing the average execution time of control-flow intensive behavioral descriptions. Our algorithm uses a control-data flow graph (CDFG) model, which preserves the parallelism inherent in the application. It explores previously unexplored regions of the solution space through its ability to overlap the schedules of independent iterative constructs, whose bodies share resources. It also incorporates well-known optimization techniques like loop unrolling in a natural fashion. This is made possible by a general loop-handling technique, which we have devised. Application of the algorithm to several common benchmarks demonstrates up to 4.8-fold improvement in expected schedule length over existing scheduling algorithms, without paying a price in terms of the bestand worst-case schedule lengths required to execute the behavioral description (in fact, frequently, the bedworst-case schedule lengths are also better for our algorithm).