Demand paging in Operating Systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is demand paging in operating systems?

Demand paging is a memory management technique where pages of data are loaded into memory only when they are needed, rather than loading the entire program at once.

beginner

How does demand paging improve system efficiency?

It reduces the amount of memory used by loading only necessary pages, which saves memory and speeds up program startup.

intermediate

What happens when a program tries to access a page not currently in memory during demand paging?

A page fault occurs, causing the operating system to load the required page from disk into memory before continuing execution.

intermediate

Explain the role of the page fault in demand paging.

A page fault signals that the requested page is not in memory. The OS then pauses the program, loads the page from disk, updates the page table, and resumes the program.

advanced

What is the difference between demand paging and pre-paging?

Demand paging loads pages only when needed, while pre-paging loads pages in advance based on predicted needs to reduce page faults.

What triggers a page to be loaded into memory in demand paging?

A When the operating system boots

B When the program starts

C When the page is accessed by the program

D When the user requests it

In demand paging, pages are loaded only when the program tries to access them.

What is a page fault?

A A signal that a page is not in memory and must be loaded

B An error in the program code

C A hardware failure

D A type of virus

A page fault occurs when a program accesses a page not currently in memory, prompting the OS to load it.

Which of the following is a benefit of demand paging?

A Avoiding page faults completely

B Loading all pages at once

C Using more memory

D Faster program startup

Demand paging loads pages only when needed, which helps programs start faster.

What does the operating system do after a page fault occurs?

A Terminates the program

B Loads the required page from disk into memory

C Ignores the fault

D Restarts the computer

The OS loads the missing page from disk to memory to continue program execution.

How does demand paging affect memory usage?

A Decreases memory usage by loading only needed pages

B Increases memory usage by loading all pages

C Has no effect on memory usage

D Uses memory randomly

Demand paging saves memory by loading only the pages that the program actually uses.

Describe how demand paging works and why it is useful in operating systems.

Think about what happens when a program tries to use a page not in memory.

Explain the difference between demand paging and pre-paging.

Consider when pages are loaded in each method.