基于分支路径跟踪的猜测访存数据Cache污染控制技术  

Mitigating Cache data pollution induced by speculative memory accessing based on branch path tracking

作　　者：刘松鹤[1] 宋焕生[1] 亓淑敏[1] 李文敏[1] 

机构地区：[1]长安大学信息工程学院,西安710064

出　　处：《计算机应用研究》2013年第7期2064-2067,共4页Application Research of Computers

基　　金：中央高校科研基金资助项目(CHD2011JC055;CHD2011JC089)

摘　　要："存储墙"问题是高性能处理器设计必须跨越的障碍之一,高效、智能的Cache系统是处理器存储体系的关键因素。具有分支预测能力的处理器在猜测执行分支路径上访存指令时取回的存储器数据所导致的Cache污染会显著影响Cache和处理器性能。分析了猜测执行和Cache数据污染对处理器性能的影响,在此基础上结合分支预测机制的特征提出了一种基于分支路径跟踪的Cache污染控制技术——Contra,通过构建分支路径跟踪表对猜测路径写入Cache的数据进行跟踪,并对这些数据的存储、访问和替换过程进行控制,有效地避免了污染数据对Cache效率的影响,提升了处理器存储系统的性能。仿真结果表明,Contra技术相对于baseline结构来说,L1 D-Cache命中率提升幅度为0.03%～6.69%,平均提升为1.80%;IPC的提升幅度为0.01%～6.60%,平均提升为2.56%。＂Memory wall＂ is one of the most important problems which must be solved for designing high performance processors.Efficient and intelligent Cache system is key component of processor’s memory system.It is a notice that Cache pollution caused by the speculative execution of memory accessing instructions in predictive path may affect the Cache and processor performance seriously.Based on the analyses of the impacts of speculative execution and Cache data pollution to processor performance,this paper proposeed a Cache pollution control technique by using branch paths tracking,which was called Contra.Firstly,it constructed a branch paths tracking table to follow the Cache data written by memory accessing instructions in speculative branch paths.Then,processes of storage,accessing and replacement to these data were particularly controlled in order to mitigate influence data pollution to Cache system and processor performance.Simulation result indicates that,Contra technique eliminates Cache pollution and upgrades performance effectively.Relative to the baseline architecture,miss rate reduction of D-Cache ranges from 0.03% to 6.69%,averagely 1.80%.Improvement of IPC ranges from 0.01% to 6.60%,ave-ragely 2.56%.

关 键 词：分支预测 猜测访问 CACHE 污染 

分 类 号：TP303[自动化与计算机技术—计算机系统结构]