填补存储器间距的一种方法——前瞻性Cache

近年来CPU速度的提高远远超过了主存,CPU与主存之间的速度差距（称存储器间距－MeoryGap）越来越大,先进的高性能Cache结构的研究对于提高系统性能显得更加重要;在传统的Cache中,仅仅依靠程序扫行时访存指令流地下的局域性保证较高的Cache命令中率,使得Cache命中率的提高受到限制,本文提出了一种新型的“前瞻性Cache”,对即将执行的指公进行提前分析,并尽可能地在Load类指令尚未实际执行这前将所需的数据预先装和Cache,这样可以提高Cache的命中率,本文阐述了前瞻性Cache结构的方案,提出了定量的评价参数,并开发了软件工具对该结构进行模拟分析,模拟检验证明,这种方法能在不扩大处理机芯片上Cache容量的基础上,进一步提高动态执行中Cache的性能,对于填补存储器间距和提高系统性能可以起到较大作用。

Lookahead Cache-a Method for Filling Memory Gap

In recent years, the growth rate of CPU speed far succeed that of memory speed, the speed gap between CPU and main memory, that is referred as "Memory Gap", is enlarging increasingly. The research on advanced, high performance Cache structure for improving system performance has become more important. In the traditional Cache, the Cache hit ratio is insured only by the address locality of memory reference instruction stream during program execution, it restricts the improvement of Cache hit ratio. This paper proposed a new type "Lookahead Cache", it prefetches the instructions and carries out the analysis for the instruction streams to be executed soon, and preload the data into Cache required for those LOAD type instruction streams to be executed, thus it can significantly increase the Cache hit ratio. This paper illustrates the design of Lookahead Cache structure, presents the quantitative evaluation parameters. In this paper, we also have developed software tool for simulating this new type Cache structure. The simulation experiment shows that this new method can further increase the Cache performance during dynamic execution and it can play an important role in filling the "Memory Gap" and improving system performance.