Application-controlled file caching policies

We consider how to improve the performance of file caching by allowing user-level control over file cache replacement decisions. We use two-level cache management: the kernel allocates physical pages to individual applications (allocation), and each application is responsible for deciding how to use its physical pages (replacement). Previous work on two-level memory management has focused on replacement, largely ignoring allocation. The main contribution of this paper is our solution to the allocation problem. Our solution allows processes to manage their own cache blocks, while at the same time maintains the dynamic allocation of cache blocks among processes. Our solution makes sure that good user-level policies can improve the file cache hit ratios of the entire system over the existing replacement approach. We evaluate our scheme by trace-based simulation, demonstrating that it leads to significant improvements in hit ratios for a variety of applications.