1.2.3 Virtual memory

Question 1

Terminating processes

Answer 1

• 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 2

Installing more Ram

Answer 2

• When we run out of RAM, 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

Paging

Answer 4

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 5

Moves pages to Hard Disk Drive

Answer 5

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 6

Move pages to RAM

Answer 6

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.