Enhancing Efficiency of Hybrid Transactional Memory Via Dynamic Data Partitioning Schemes

Abstract

Transactional Memory (TM) is an emerging paradigm that promises to significantly ease the development of parallel programs. Hybrid TM (HyTM) is probably the most promising implementation of the TM abstraction, which seeks to combine the high efficiency of hardware implementations (HTM) with the robustness and flexibility of software-based ones (STM). Unfortunately, though, existing Hybrid TM systems are known to suffer from high overheads to guarantee correct synchronization between concurrent transactions executing in hardware and software. This article introduces DMP-TM (Dynamic Memory Partitioning-TM), a novel HyTM algorithm that exploits, to the best of our knowledge for the first time in the literature, the idea of leveraging operating system-level memory protection mechanisms to detect conflicts between HTM and STM transactions. This innovative design allows for employing highly scalable STM implementations, while avoiding instrumentation on the HTM path. This allows DMP-TM to achieve up to ~ 20× speedups compared to state of the art Hybrid TM solutions in uncontended workloads. Further, thanks to the use of simple and lightweight self-tuning mechanisms, DMP-TM achieves robust performance even in unfavourable workload that exhibits high contention between the STM and HTM path.