LogSPoTM: a scalable thread level speculation model based on transactional memory

Abstract

Thread level speculation (TLS) and transactional memory (TM) are both proposed to address the problem of productivity in multi-core era. Both of them require similar underlying support. In this paper, we propose a low-design-complexity approach to effective unified support for both TLS & TM, by extending a scalable TM model to support TLS. The baseline TM model chosen is LogTM. A distributed hardware arbitration mechanism is also proposed to intensify scalability. This method takes advantage of hardware resources introduced by TM, resulting simplified hardware design. Moreover, it provides rich semantics of both TLS and TM to programmers. Five representative benchmarks have been adopted to evaluate performance characteristics of our TLS model under different memory access patterns. Influence of design choices such as interconnection is also studied. The evaluation shows that the new system performs well in most of the benchmarks in spite of its simplicity, resulting average region speedups around 3.5 at four threads.