Page Size and Address Translations

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pages should be fairly large (KBs) because we pay the access time to get them from the disk
virtual page number (VPN) to physical page frame number (PPFN) is done by memory management unit (MMU)
instead of using tags to make them fully-associative (too many tags to compare) we use page tables
page table is an in-memory data structure for hardware memory management unit to convert from virtual page number to physical page frame number
like breaking 555-123-4567 to three levels of hash map [555] → [123] → [4567]
using multi-level page table can save space.
example: for 32-bit virtual address, 1 GB physical memory, and 4 kB pages how many bits do we need for the frame number? 1GB = 30 physical address bits. 4KB is 12 offset bits. Thus we need 30-12 = 18 bits for the frame number.
but this multi-level can also be very expensive, because we need to lookup that many times
- potential solution: cache this! called translation look-aside buffers.