To ARC or Not to ARC

Cache replacement algorithms have focused on managing caches that are in the datapath. In datapath caches, every cache miss results in a cache update. Cache updates are expensive because they induce cache insertion and cache eviction overheads which can be detrimental to both cache performance and cache device lifetime. Nondatapath caches, such as host-side flash caches, allow the flexibility of not having to update the cache on each miss. We propose the multi-modal adaptive replacement cache (mARC), a new cache replacement algorithm that extends the adaptive replacement cache (ARC) algorithm for non-datapath caches. Our initial trace-driven simulation experiments suggest that mARC improves the cache performance over ARC while significantly reducing the number of cache updates for two sets of storage I/O workloads from MSR Cambridge and FIU.