Host OS page cache hit ratio improvement based on guest OS page drop

Abstract

In a virtualized environment, such as a cloud computing environment, guest and host operating systems (OS) run simultaneously. Both of the operating systems have page caches for disk accesses. In such an environment, the second level cache does not work effectively because of negative temporal locality of access and duplicated storing in both the caches. In this paper, we propose a method for increasing the hit ratio of the host operating system page cache. The method monitors pages dropped from the guest operating system page cache and stores the pages into the host operating system cache. After the proposal, we introduce the design and implementation of our system. Our implementation aims to be applicable without modification to the hypervisor, and thus it can be applied for an environment with a proprietary hypervisor. Lastly, we present the evaluation of the hit ratio of the host operating system cache, and then demonstrate that our method can improve the cache hit ratio.