Grouping Memory Consistency Model for Parallel-Multithreaded Shared-Memory Multiprocessor Systems

In this paper, we propose a hardware-centric memory consistency model particularly for shared-memory multiprocessors with parallel-multithreaded processing elements. According to the behavior of critical sections and the feature of parallel-multithreaded processors, we extend the release consistency model to a more relaxed memory model. A release reference at the end of a critical section can be executed locally regardless of whether all of its previous ordinary references have performed. The requirement is that another thread on the same processor is waiting for the lock to be freed. Two new instructions and two additional macros are needed to properly label a program for our proposed model. Moreover, we use a table per processing element to determine if there are any threads waiting for a specific lock. We have used five benchmark programs in the SPLASH suite to evaluate the performance gain for the new model. According to the simulation results, our proposed model is superior to the release consistency model up to 25%.