Rather Than a Two-Level Page Table, What Other Page Table

Essay

Rather than a two-level page table, what other page table architecture could be used to reduce the memory foot print of page tables for the 64-bit address space from the last question? Assume that you do not need to map the full address space, but some small fraction (people typically do not have 264 bytes of physical memory). However, you should assume that the virtual pages that are mapped are uniformly distributed across the virtual address space (i.e. it is not only the low addresses or high addresses that are mapped, but rather a few pages from all ranges of memory).