Remote subpaging across a fast network

While improvements in semiconductor technology have made it possible to accommodate a large physical memory in today's machines, the need for supporting an even larger virtual address space continues unabated. Improvements in disk access times have however lagged improvements in both processor and memory speeds. Recent advances in networking technology has made it possible to go out on the network and access the physical memory on other machines at a cost lower than accessing the local disk. This paper describes a system implemented for such a remote paging environment. This system allows us to use a fine grain (a subpage) data transfer unit for remote memory paging and to employ different algorithms for determining when and how to transfer these units. The novelty of our implementation is that all the policy decisions about the subpage size and the subpaging algorithm are made at the user level, thus letting applications choose their own set of parameters. Performance results indicate that applications can benefit significantly from this flexibility.