Cache自适应写分配策略

A Cache Adaptive Write Allocate Policy

处理器所能提供的有效带宽是目前制约处理器性能提高的关键因素.通过对Cache写失效行为的分析,提出了一种新的提高处理器带宽利用率的Cache写失效处理策略——Cache自适应写分配策略.该策略在访存失效队列中收集全修改Cache块,对全修改Cache块采用非写分配策略,并能够自适应地切换为写分配策略.与传统的Cache写失效处理策略相比,Cache自适应写分配策略硬件代价小,避免了不必要的数据传输,降低Cache污染,减少存储管理队列阻塞的频率.结果表明,采用Cache自适应写分配策略,STREAM基准测试程序带宽平均提高62.6%,SPECCPU2000程序的IPC值平均提高5.9%.

The bandwidth becomes the major bottleneck of the performance improvement for modern microprocessors. A cache adaptive write allocate policy that improves the bandwidth of microprocessor significantly is proposed by investigating cache store misses. The cache adaptive write allocate policy collects fully modified blocks in miss queue. Fully modified blocks are written to lower level memory based on nonwrite allocate policy which can switch to write allocate policy adaptively. Compared with other cache store miss policies, the cache adaptive write allocate policy avoids unnecessary memory traffic, reduces cache pollution and decreases load ＆ store queue full rate without increasing hardware overhead. Experiment results indicate that on average 62.6% memory bandwidth in STREAM benchmarks is improved by utilizing the cache adaptive write allocate policy. The performance of SPEC CPU 2000 benchmarks is also improved efficiently. The average IPC speedup is 5.9 %.