CSE 131 Lecture Notes - Lecture 16: Dirty Bit, Page Table, Logical Address
Document Summary
Page frame number is the index in physical memory basically. Page table resides in main (physical) memory. Page table base register (ptbr) points to the page table. Page table length register (ptlr) contains length of page table: restricts maximum legal logical address. Second access reads the data / instruction from memory. Can"t avoid second access (we need the value from memory) Eliminate first access by keeping a hardware cache (called a translation lookaside buffer or tlb) of recently used page table entries. Observation: most access to memory is done to a small number of pages. Search the tlb for the desired logical page number. Get frame number from page table in memory. Replace an entry in the tlb with the logical and physical page numbers from this reference. All entries are matched to the input address in parallel. No need to go to the page table if the address is in tlb.
