Virtual Memory

Question 1

What does virtual memory mean?

Answer 1

It means that there is no chance of programs overwriting each other

Question 2

What does segmentation allow?

Answer 2

It allows us to divide the memory space into purposeful segments and assign virtual addresses to them

Question 3

What are the problems with segmentation?

Answer 3

• Still have to load libraries multiple times
• Still can’t use more memory than actually exists
• Programs will never have access to a full segment: some of it is used for addressing
• Problems with memory holes not fixed

Question 4

What does paging do?

Answer 4

Paging splits available RAM into pages which give programs virtual space.

Question 5

What are pages useful for?

Answer 5

They can be re used to save memory

Question 6

How does the OS load data from secondary storage to RAM?

Answer 6

• It determines the location of data on disk
• Obtains an empty page from RAM to use as a container for the data
• Load the requested data into an available page
• Update the page table to refer to the new page
• Return control to program

Question 7

What is swapping?

Answer 7

A way of moving a whole process from the RAM onto the HDD

Question 8

What does swapping do?

Answer 8

Saves the status of the currently running program

Question 9

Is swapping or paging slower?

Answer 9

Swapping is very slow, while paging is slow.