Virtual memory in one address space
Virtual memory gives a process addresses it can use while the system maps them to physical memory under controlled rules.
Learning objectives
- Separate a virtual address from a physical location.
- Explain pages and address translation at a high level.
Useful illusion, real limits
A process operates in a virtual address space. Hardware and the OS cooperate to translate permitted virtual addresses to physical memory. Page-sized regions and page tables are common mechanisms. This abstraction helps isolate processes and lets the system manage memory flexibly.
Page faults
If a required page is not currently resident or access is not permitted, the processor traps into OS handling. A fault can lead to loading data, or to an error if the access is invalid. Virtual memory is not unlimited fast RAM; moving data from storage is much slower than accessing memory.
Common mistakes and references
- Virtual memory is not the same thing as a memory leak.
- Exact page sizes and replacement policies are implementation dependent.