What’s the difference of RAM and Virtual Memory (VM)?

I got curious…looking at it made me think how it differs from one another, or both are just an individual things in one place with one purpose?

To know the real memory consumes by a program, do we have to sum up this two to get the total memory value it is using?

 

The RAM is the physical memory of your system.

The VM is a file, on your disk, that is used when your RAM is full. When you need to put a process on the RAM, the processes that aren't needed to use the RAM, are sent to the VM, and when that processes are needed again, they are sent again to the RAM.

When you need a process, if the file aren't on the RAM, the system will take much more time to load those files from the VM to the RAM...

That is why we should have as much as possible of RAM on our system...

 

I have run with no paging for a while now with no probs.With a gig of ram and only use is for surfing and testing security apps there seems to be no need for my habits.

Some intense games require to set a page file regardless of the amount of ram
But Taskmanager will allways show pagefile in use-

Quote-

"Note: For the most part, this paging does not take place in the page file, this
form of paging takes place within the direct location of the .exe or .the dll"
http://www.osnn.net/articles.php?action=show&showarticle=99

 

Franklin

I found the link you gave to, Understanding Virtual Memory and the Page File etc, a very good and informative read and source.

Thanks


StevieO

 

i think that once you have 2GB of RAM you can turn off your virtual memory and thus speed up your system with no other problems.

 

You can reduce performance by not having a page file even with lots of ram. In general its pointless turning off the pagefile.

Gigs of ram, hold lots and lots of pages that are not used or in use, that would be better off being swapped out to your pagefile and used for the system cache instead, for caching data and files that are in demand.
Not only that but its better to have a bit of spare ram and unused pages paged out to disc for sudden RAM demand, from the system cache (think big file write) or launching a new app. You will actually end up with excess disk thrashing, which is a massive bottleneck on any computer.
NT is smart enough to shrink the cache if it cant page to disk as needed and will prefer ram to use pages as opposed to cache, to minimise pagefile use anyhow.

This is why in ANY pagable OS you always use a pagefile as default.

 

this seems to be a good article about this subject, and apparently i heard wrong and you really shouldn't turn it off....here's the article http://aumha.org/win5/a/xpvm.php

 

I run WinXP Pro SP2 with 1GB RAM and these Virtual memory settings:
Total paging file size for all drives - there are: 1 80GB, and 1 40GB: 0 MB, i.e. no paging file

When I launch Windows Task Manager, and click on Performance, I get these readings:

Kernel Memory (K)
Total 108996 <-- changes
Paged 91952 <-- changes
NonPaged 18080

Physical Memory (K)
Total 1046248
Available 498624 <-- changes
System Cache 641784 <-- changes

So, the fact that I have turned off the paging file only apparently applies to application programs, not the kernel which must be using a small page file reserved for itself, whereas the NonPaged area is clearly resident.

-- Tom

 

There is a registry tweak somewhere to turn off paging of the kernel also. I don't recall what it is, but I'm sure you can Google and find it pretty easily..