Productivity and Performance: Improving Consumability of Hardware Transactional Memory through a Real-World Case Study

Hardware transactional memory (HTM) is a promising technology to improve the productivity of parallel programming. However, a general agreement has not been reached on the consumability of HTM. User experiences indicate that HTM interface is not straightforward to be adopted by programmers to parallelize existing commercial applications, because of the internal limitation of HTM and the difficulties to identify shared variables hidden in the code. In this paper we demonstrate that, with well-designed encapsulation, HTM can deliver good consumability. Based on the study of a typical commercial application in supply chain simulations GBSE, we develop a general scheduling engine that encapsulates the HTM interface. With the engine, we can convert the sequential program to multi-threaded model without changing any source code for the simulation logic. The time spent on parallelization is reduced from two months to one week, and the performance is close to the manually tuned counterpart with fine-grained locks.