Can someone explain in detail what Paging File is?

[CrowDog]

I have a program called Cacheman that reports the Pagefile usage...and windows taskmanager alsoreports pagefile usage. I dont have a COMPLETE understanding of what exactly this means. Can someone please explain?

Im in Win XP Pro. My HDD is Maxtor 20gb 5400rpm.

 

[bozo1]

A Page file or Swapfile is just a chunk of space on your hard drive that your operating system can use as extra memory. It uses the file as an extension of your physical RAM. If you run out of RAM, it uses that space to store data that normally would be in your physical RAM. (even though it is much slower) Your OS also uses it to store some data that isn't needed often (and doesn't really matter if it is slower to access) so as not to eat up physcal RAM with less important stuff.

 

[PrincessGuard]

Very simply (or maybe not 😛):

Windows uses a virtual memory model, i.e. all programs are able to access the full memory address space (e.g. 4GB) regardless of how much physical memory you actually have. That is, every program thinks it has 4GB of RAM all to itself.

Windows does this by dividing both virtual and physical memory into pages of a certain size. Pages may be in physical memory or in the page file on your hard drive. When a program accesses something in (virtual) page 12345, for example, Windows checks to see if the page is in physical memory. If it is, then all is good.

If the page is not in physical memory, then it must be swapped in from your page file. If Windows finds an unused frame in physical memory, then it can just stick page 12345 in there. If there are no unused frames of physical memory, then Windows will move the contents of a physical frame to the page file and then stick page 12345 in its old spot.

This is a basic explanation of virtual memory. Windows does swap stuff to your page file even if there is space in physical memory.