Impact of Version Management for Transactional Memories on Phase-Change Memories

Two of the major issues in current computer systems are energy consumption and how to explore concurrent systems in a correct and efficient way. Solutions for these hazards may be sought both in hardware and in software. Phase-Change Memory (PCM) is a memory technology intended to replace DRAMs (Dynamic Random Access Memories) as the main memory, providing reduced static power consumption. Their main problem is related to write operations that are slow and wear their material. Transactional Memories are synchronization methods developed to reduce the limitations of lock-based synchronization. Their main advantages are related to being high-level and allowing composition and reuse of code, besides the absence of deadlocks. The objective of this study is to analyze the impact of different versioning managers (VMs) for transactional memories in PCMs. The lazy versioning/lazy acquisition scheme for version management presented the lowest wear on the PCM in 3 of 7 benchmarks analyzed, and results similar to the alternative versioning for the other 4~benchmarks. These results are related to the number of aborts of VMs, where this VM presents a much smaller number of aborts than the others, up to 39 times less aborts in the experiment with the benchmark Kmeans with 64 threads.