Virtual Memory

Question 1

How can we fix running out of primary memory

Answer 1

Purchasing more RAM
Terminating processes
Virtual Memory

Question 2

Installing more RAM

Answer 2

we can purchase and install more RAM so that we can store more data.
This is not always ideal because:
RAM can be expensive.
We may only need more memory on a temporary basis.

Question 3

Virtual Memory

Answer 3

Virtual Memory is a technique where we use secondary storage as if it were RAM.
Virtual memory is not always ideal since:
Virtual Memory can have negative impacts on performance.
Virtual Memory can have negative impacts on the health of Solid State Disks (SSDs).
We might have limited space in secondary storage.

Question 4

Terminating processes

Answer 4

Each program/process will use a certain amount of memory.
By closing some processes that we are not using, we can free the memory that they are using.
This is not always possible because we may need all the processes.

Question 5

How does virtual Memory work

Answer 5

Paging
Moves pages to HDD
Moves pages to RAM

Question 6

Paging

Answer 6

Memory can be split into sections called ‘pages’.

Virtual Memory works by moving these pages between the Random Access Memory (RAM) and the secondary storage.

Question 7

Moving pages to HDD

Answer 7

If a page is not being used, then we might want to put it into Virtual Memory.
When a page is moved to the HDD, it is put into a special file called the pagefile.
Other processes can then use the memory that we just freed in the RAM.

Question 8

Moving pages to RAM

Answer 8

When we want to use a page again, we first need to move it back to the RAM.
We do this by swapping the page that we want with one that is already in the RAM.