Topic 5 · Resource Management (HL)

Each process gets its OWN linear address space; OS+MMU translate to physical RAM.

Isolation (security + stability) + Abstraction (programmer simplicity) + Capacity (run more than fits in RAM).

Fixed-size chunk, typically 4 KB. Unit of virtual→physical mapping.

A page-sized slot in physical RAM. Page tables map pages → frames.

Per-process table mapping each virtual page number to a physical frame (or 'on disk').

Memory Management Unit — hardware on the CPU that performs page-table lookups on every memory access.

Translation Lookaside Buffer — small cache of recent page-table lookups for speed.

Page not in RAM → interrupt → OS fetches from disk (~10 ms) → retry. 100,000× slower than RAM (~100 ns).

Working set > RAM → constant page faults → CPU idle + disk 100% → system unusable. Fix: free RAM.

Hardware-enforced via MMU + page tables. Process A simply CAN'T address Process B's pages. Segfault on violation.