A) What is the minimum number of memory accesses needed to access a location in virtual memory?

 

For the following questions, assume we have a Translation Look-aside Buffer (TLB) and 2-level page tables, as illustrated in the lecture video. The following ask about the cache, memory, and disk accesses needed when reading or writing a single data word from a virtual memory (VM) address. Since VM is complex, we will limit our attention to certain types of accesses. As stated above, count only accesses for reading or writing a data word. Do not count accesses for fetching instructions. Count only access to page tables and the target address. The cache and TLB are separate hardware, so accessing them does not count as memory access. Count reading a page table entry or a data word as a single access. Do not count any memory and disk accesses necessary for replacing a VM page, i.e., writing the old page to disk and loading a new page from disk.