仅由硬件控制的传统替换策略严重限制了高速缓存(cache)性能的提高.该文提出一种面向嵌入式应用的软件可控cache的实现方法.在传统结构上增加一个软件控制器,根据软件配置实现如下3种操作:对于访问开销大且生命期分布均匀的数据在cache中保留副本;对造成cache预取效率下降的数据由处理器直接与外存通信;对某一时刻被频繁访问的数据在其有效生命期内优先停留在cache中.实验结果表明,对于数据指令统一cache,系统整体性能的提升可达11%,同时总线占用率减少28%左右.%Recent researches show that traditional hardware-only cache replacement strategies seriously hamper the improvement of cache performance. This paper proposes a novel scheme of software-controllable cache for embedded systems. In this scheme, a software-controller module is added to the traditional architecture to implement the following three operations controlled by software: For data that incur heavy access cost and have a wide activity space, a copy is retained in the cache. Data that cause a drop in the cache pre-fetching temporal locality are directly exchanged between the processor and the external memory. Data with less access cost and a narrow activity space preferentially remain in the cache during activities. Simulation results show that the proposed approach can improve the system performance by 11% and reduce bus occupancy by 28%.
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