An Improved Design on Performance and Cache Miss Rate for Set-Associative I-Cache

Access with prediction has been an effective approach to reduce the power consumption of set-associative I-cache. However it decreases the performance meanwhile. This paper improved LAW (last accessed way) based I-cache design, which takes both the replacement and predicting access policy into account. By replacing and accessing along the last accessed way, the CMR (cache miss rate) and PMR (predict miss rate) are significantly improved. We extend the scope of application of LAW based policy by subdividing those uncertain occasions with MRU (most recently used) way prediction. Simulations show that compared with the original LAW approach, such a 16KB, 4-way and 32B-line-size I-cache can improve 0.833% performance on average, with the energy consumption increased by 1.498% only. Compared with the conventional set associative I-cache, the proposed design, which is called eLAW, reduces almost 17.93% CMR and 43%-59% energy consumption on average.