Research Article Using Heuristic Value Prediction and Dynamic Task Granularity Resizing to Improve Software Speculation

permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Exploiting potential thread-level parallelism (TLP) is becoming the key factor to improving performance of programs onmulticore ormany-core systems. Among various kinds of parallel executionmodels, the software-based speculative parallelmodel has become a research focus due to its low cost, high efficiency, flexibility, and scalability. The performance of the guest program under the software-based speculative parallel execution model is closely related to the speculation accuracy, the control overhead, and the rollback overhead of themodel. In this paper, we first analyzed the conventional speculative parallelmodel and presented an analytic model of its expectation of the overall overhead, then optimized the conventional model based on the analytic model, and finally proposed a novel speculative parallel model named HEUSPEC. The HEUSPEC model includes three key techniques, namely, the heuristic value prediction, the value based correctness checking, and the dynamic task granularity resizing. We have implemented the runtime system of the model in ANSI C language.The experiment results show that when the speedup of the HEUSPECmodel can reach 2.20 on the average (15 % higher than conventional model) when depth is equal to 3 and 4.51 on the average (12 % higher than conventional model) when speculative depth is equal to 7. Besides, it shows good scalability and lower memory cost. 1