Dynamic Buffer Cache Management Scheme Based on Simple and Aggressive Prefetching

Many replacement and prefetching policies have re cently been proposed for buffer cache management. However, many real operating systems, including GNU/Linux, generally use the simple Least Recently Used (LRU) replacement policy with prefetching be ing employed in special situations such as when sequen tiality is detected. In this paper, we propose the SA W 2 R scheme that integrates buer management and prefetching, where prefetching is done constantly in ag gressive fashion. The scheme is simple to implement making it a feasible solution in real systems. In its ba sic form, for buffer replacement, it uses the LRU policy. However, its modular design allows for any replacement policy to be incorporated into the scheme. For prefetch ing, it uses the LRU-One Block Lookahead (LRU-OBL) approach, eliminating any extra burden that is gener ally necessary in other prefetching approaches. Imple mentation studies based on the GNU/Linux kernel ver sion 2.2.14 show that the SA-W2R performs better than the current version of GNU/Linux with a maximum in creases of 23 % for the workloads considered.