virtual memory 1

[genice]

what is virtual memory, pls. explain and give the specific functions.

 

[cyberspace]

Hi there,

In a nutshell, it is a special area of the hard drive that is used when there is no free RAM available. Data is swapped (hence the term swap file) to and from the hard drive.

It can have performance impact though if you rely on it too much, since accessing a hard drive is many many times slower than accessing RAM.

This information is well documented on the internet, so instead of me or any other member giving you a lengthy reply, I suggest you do a google search for more detailed information. I don't mean that rudely by the way, it's just easier to google for it!

Hope you find this useful.


'When all else fails.......read the manual'

 

[cdogg]

Well, I hate to be the party crasher, but unfortunately, that's a common misunderstanding of what virtual memory really is.

Virtual memory consists of more than just the swap file. It includes the VAS (Virtual Address Space), physical memory (RAM, L1/L2 cache on the CPU, etc), and memory management techniques which make the various memory locations appear as one "virtual" memory region to the Operating System. The swap file is only a piece of what virtual memory is all about.

Having said that, genice I encourage you to search the net like cyberspace said. The way you have asked the question makes it appear that this is nothing more than a homework assignment that you're looking for answers on...

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[cyberspace]

Just to clarify, I am aware of VM being more than a swap file, my description was only intended as a very brief summary.

Theres not alot of point in writing out an essay when there are countless resources available online.

'When all else fails.......read the manual'

 

[cdogg]

it is a special area of the hard drive that is used when there is no free RAM available

That sounds like a definition of the swap file, and in no way encapsulates what virtual memory is. Sorry if I took that the wrong way...

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[cyberspace]

Fair enough, but it is relevant and is a major factor of VM.

http://www.google.co.uk/search?sour...GGLG:2005-32,GGLG:en&q=define:+virtual+memory

'When all else fails.......read the manual'

 

[cdogg]

Yeah, that link is a perfect example of how many people out there use the term "swapfile" and "virtual memory" interchangeably. Here's what wikipedia says about that:

The term "virtual memory" is often confused with "memory swapping" (or "page/swap file" use), probably due in part to the prolific Microsoft Windows family of operating systems referring to the enabling/disabling of memory swapping as virtual memory. In fact, Windows uses paged memory and virtual memory addressing, even if the so called "virtual memory" is disabled.

Notice that it says Windows still uses the swapfile, even when the "virtual memory" setting is disabled.

If you could compare virtual memory to a house...the swapfile would be like the kitchen or the living room, only a piece of what you would expect to see in every house.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884