Allocation by Conflict: A Simple Effective Multilateral Cache Management Scheme

Several schemes have been proposed that incorporate an auxiliary buffer to improve the performance of a given size cache. Victim caching, aims to reduce the impact of conflict misses in direct-mapped caches. Victim offers competitive performance benefits, but requires a costly data path for swaps and saves between the main cache and the added buffer. Several multilateral schemes (e.g. NTS, PCS) offer competitive performance with Victim across a wide range of associativities, but require no swap/save data path. While these schemes perform well overall, their overall performance lags that of Victim when the main cache is direct-mapped. Furthermore, they also require costly hardware support, but in the form of history tables for maintaining allocation decision information. This paper introduces a new multilateral cache management scheme, Allocation By Conflict (ABC), which generally outperforms Victim, NTS, and PCS. Furthermore, ABC has the lowest hardware requirements of any multilateral scheme –– only a single additional bit per block in the main cache is required to maintain usage information for the allocation decision process, and no swap/save data path is needed.