PMESI:一种优化进程私有数据访问的缓存一致性协议

PMESI:optimizing memory performance by selectively deactivating cache coherence for private pages

并行应用程序中绝大部分的访存是对私有数据的访问,在cache一致性协议上不会产生冲突。传统一致性协议没有根据程序私有数据的访问模式进行针对性设计,存在着很大的优化空间。针对以上的问题,提出了一种支持私有状态的cache一致性协议PMESI,通过动态关闭和激活内存空间的cache一致性目录,优化私有内存空间的访问延迟和功耗。通过时钟精确模拟器的测试,PMESI协议优化了程序中54%的访存,并行程序的执行时间平均缩短了9%。

Parallel program has significant percentage of memory requests that target only private data, which does not need to resolve cache coherence conflicts. Yet traditional coherence protocol does not distinguish between shared and private blocks, which leaves much optimization space. An optimized cache coherence protocol, called PMESI, which dynamically deactivates coherence maintenance for private memory space, was suggested. PMESI achieves two distinguishing features： the reduction of memory access latency and system power consumption. Simulation results on the cycle accurate simulator show that 54% memory references can be efficiently optimized and the program execution time is reduced 9% on average.