Moving home-based lazy release consistency for shared virtual memory systems

Abstract

While Shared Virtual Memory is a cost-effective way to provide an illusion of shared memory to programmers, the performance of the system is limited by its inherent overheads. Several protocols such as Lazy Release Consistency (LRC) and Home-based LRC (HLRC) have been suggested to overcome the overheads. In this paper we propose a new all-software protocol, Moving Home-based LRC (MHLRC). Its main contribution is to introduce a new concept, Moving Home. Using it, our protocol provides 4 efficient functionalities: (a) providing migration mechanism, (b) eliminating the duty of updating the home copy at the end of an interval, (c) providing an adaptive home locating scheme, and (d) simplifying the update procedure on a stale copy. To evaluate our protocol, we implemented a prototype of MHLRC. The experiment with 4 benchmarks showed that our protocol improved the performance of the system by on the average 10% over LRC, and by up to 96% over HLRC. From the detailed analysis, we found that the improvement mainly comes from the reduction of the coherence action overhead. Our protocol reduced the number of diff operations executed during computation up to 64%(FFT)/spl sim/0.4%(SOR) against LRC and 56%(FFT)/spl sim/0.3%(SOR) against HLRC. It also reduces the requirement for memory and network bandwidth.