Operating systemsLesson 2 of 4 in the course Memory management

Paging: Address Translation, Page Faults, and Virtual-Memory Management

5 flashcards · 4 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Paging is a memory-management technique that lets a process use a logical address space without requiring its data to occupy one continuous region of physical RAM. This lesson introduces pages, page frames, address translation, and the historical development of paging.

A process refers to memory through logical addresses (also called virtual addresses). Physical RAM is divided into fixed-size units called page frames. The process's address space is divided into equally sized pages. Because a page can be placed in any available frame, the process's physical memory need not be contiguous.

All flashcards

What is a page?
A fixed-size unit of a process's logical or virtual address space that can be mapped to a physical page frame.
What is a page frame?
A fixed-size unit of physical RAM that can hold one page; frames and pages have matching sizes.
What makes a page dirty?
It has been modified in RAM since loading, or its contents otherwise need to be preserved.
What is a working set?
The group of pages a program actively uses during a particular period.
What is copy-on-write?
A technique that delays making a private copy of a shared page until a process attempts to modify it.

Quiz questions

  1. When a process references a valid page that is absent from RAM, what does the operating system typically do?Answer: It loads the page into a frame, updates the page table, and retries the instruction.
  2. Before reusing the frame of a dirty page, what does the operating system generally need to do?Answer: Write the page's contents to secondary storage if they need to be preserved.
  3. Which page does the least recently used (LRU) replacement strategy favor evicting?Answer: The resident page that has gone the longest without being accessed.
  4. Under demand paging, when is a page loaded into RAM?Answer: After a process references the page and triggers a page fault.

Based on the Wikipedia article Memory paging, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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