Notes / University Notes / Operating System / Chapter 9: Virtual Memory Management

Chapter 9: Virtual Memory Management

Created: 2025-12-16Updated: 2025-12-16

Running a process without keeping all of it in memory: faulting pages in on demand, deciding which to evict, and what that costs on average.

Virtual Memory: separation of user logical memory from physical memory
- extremely large process
- increase CPU/resource utilization
- free programmer from memory limitation
- run programs faster -- less I/O would be needed to load or swap

Demand Paging

bring a page into memory only when it is needed, not bring whole process
- less process creation time
- less memory needed → more users
Valid-Invalid Bit in page table
- (dealt by segmentation) invalid reference → abort
- not-in-memory → Page Fault → Paging(bring page into memory)
pure demand paging
- start a process with no page
- never bring a page into memory until it's referenced
.