SSARC: The Short-Sighted Adaptive Replacement Cache

As the performance gap between disks and processors continues to increase, dozens of cache replacement policies come up to handle the problem. Unfortunately, most of the policies are static. Nimrod Megiddo etc put forward a low overhead adaptive policy called ARC. It outperforms most of the static policies in most situations. But, ARC adapts itself to the workloads by the feedback of the missed pages. It hasn ´t carried out the adaption before missed pages are discovered. We propose a high performance adaptive replacement policy. It adapts itself to the workloads by the feedback of the hit pages, so, it is more sensitive to the changes of the workloads than ARC. As the policy stares at the tails of the queues regardless of other pages, we name the policy as short-sighted adaptive replacement policy. The ARC usually regrets for the missed pages and wishes to rescue the neighborhood of them. However, SSARC endeavors to protect the would-be-reused pages from being replaced aggressively. So, it outperforms ARC in most situations. We compared SSARC with LRU, 2Q and ARC. The trace-driven experiments represent that SSARC gains higher performance.