Page Replacement

Question 1

What is demand paging?

Answer 1

Puts pages in memory when needed.

Question 2

Trying to access a page not currently in memory is called what?

Answer 2

A page fault

Question 3

What swaps unnecessary pages?

Answer 3

Optimal Page Replacement

Question 4

What are the advantages and disadvantages of Optimal page replacement.

Answer 4

Advantage
- Minimal Damage
-Looks forward in time

Disadvantage
- Unimplementable because it requires knowledge of future memory

Question 5

Describe how each page replacement kicks out a page.

Answer 5

Optimal - Kicks out page with longest time before used again.

FIFO - Kicks out oldest page

LRU - kicks out page used less recently

Question 6

What are the advantages and disadvantages of FIFO page replacement.

Answer 6

Advantages
- simple and easy to use
- very active

Disadvantages
- increase of page faults
- might throw out important pages

Question 7

What are the advantages and disadvantages of LRU page replacement.

Answer 7

Advantages
-Gives less page faults

Disadvantages
- expensive and more complex
-very consuming

Question 8

When processes have excessive page faults and spend more time swapping than working it is called __________.

Answer 8

Thrashing

Question 9

What is a working set?

Answer 9

Pages used by a process