Memory Management

Memory management involves calculating and assigning certain amounts of memory to each task in a certain way to gain optimal performance from the computer.

There are three ways computers can manage memory:


Paging

Paging is where the RAM is split into equal pieces.

Pages are the equal segments that make up the RAM. They are used to identify and locate data (they are what data is stored on and labelled as).
 For example: each page makes up 10kb of the RAM. A 15kb piece of data would take up 2 pages (so 5kb of RAM would be wasted) and then that data would be labelled as being on pages 1 & 2.


Segmentation


Segmentation allows each of the segments to be fluid (so they can adjust to the size of the file). So a 15kb bit of data could use one segment of 10kb and another segment of 5kb. No RAM would be wasted however this does make monitoring how much storage is left in the RAM more difficult to predict for the computer.


Virtual Memory
Virtual memory is used when the RAM becomes full. Data gets passed between the hard drive and RAM when it is required. This slows the computer down however because the read/write of hard drives are usually quite slow.

When Virtual memory is used a problem called Disk Thrashing can occur. Disk thrashing occurs when data is constantly being passed between the hard drive and RAM. The hard drive is constantly and reading and writing which will cause it to wear out. The computer will spend more time reading and writing to the hard drive then it will actually be processing the data. This will cause programs to ‘lock up’ and ‘not respond’.

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