Synchronization state buffer: supporting efficient fine-grain synchronization on many-core architectures

Efficient fine-grain synchronization is extremely important to effectively harness the computational power of many-core architectures. However, designing and implementing finegrain synchronization in such architectures presents several challenges, including issues of synchronization induced overhead, storage cost, scalability, and the level of granularity to which synchronization is applicable. This paper proposes the Synchronization State Buffer (SSB), a scalable architectural design for fine-grain synchronization that efficiently performs synchronizations between concurrent threads. The design of SSB is motivated by the following observation: at any instance during the parallel execution only a small fraction of memory locations are actively participating in synchronization. Based on this observation we present a fine-grain synchronization design that records and manages the states of frequently synchronized data using modest hardware support. We have implemented the SSB design in the context of the 160-core IBM Cyclops-64 architecture. Using detailed simulation, we present our experience for a set of benchmarks with different workload characteristics.