CST 334 Week 4

This week I learned about Paging. Paging is a strategy for allocating memory of a virtual address to memory. To accomplish this a virtual page number obtained from the virtual address is used to index a page table. Entries in the page table contain page frame number, which provides information on where the page is stored in physical memory. I learned that while paging provides an efficient strategy to memory management, references to the page table are expensive. To resolve this issue a cache called the translation lookaside buffer (TLB) is used to track previous translation made by the page table. If a hit occurs, the OS does not have to perform the costly operation of accessing the page table for address translations. I also learned about the various approaches to storing translations in the TLB such as the optimal policy, least recently used, first in first out, and random. Upon each context switch, the TLB is cleared and a new page table is created for each new process. The first type of page table I learned was linear page tables. These page tables are simple to implement but can result in large amounts of memory being dedicated just to the page table. Multilevel page tables provide a solution to this issue and contain more than multiple layers with pointers to different page tables. Also, this week’s programming assignment provided me with more experience with bit manipulation.  While I still have a lot to learn about C and binary arithmetic, I felt much more comfortable this week than I did last week.