Physical Memory VS Page File

The difference between physical memory and the page file has always puzzled me. I use a memory monitoring program called MemInfo, and as you can see below, it displays the current memory and page file usage.

http://img178.imageshack.us/img178/5517/meminfoqv5.png

I understand that the page file is a combination of the virtual memory (swap file) and physical memory. But what baffles me is how the amounts usually differ, like in the screenshot above. Can anyone tell me why?

 

Actually, virtual memory is the total combination of the paging file and RAM. Your paging file is set by Windows default to be approximately 1.5 times your RAM. That is why the paging file and RAM differ in size.

P.S.: I noticed your AV is deactivated in the screenshot. Are you aware of that?

 

Eh, I could have sworn there were more posts here in this thread...

Anyway, yes, I disabled my AV, because I only use it to scan what I download (don't worry, I'm an experienced enthusiast who has never gotten viruses or spyware )

I know how Windows deals with the paging file/memory, but still, how can it possibly be using 436 MB of physical memory while the page file reports that 359 MB is being used? Shouldn't they be about the same amount? Or is it always being reported incorrectly?

 

Your physical memory and page file are different.

Your physical memory is your actual system memory usage. Your memory slots on your motherboard, their usage / total alloted memory. Your screenshot shows you have 1GB of RAM and 436MB of information is currently stored in it.

Your paging file is stored on your harddisk and is controlled by Windows. Swapping and Paging are two different techniques Microsoft uses, yet they refer to them interchangeably. Swapping is taking information from the system memory and moving it to your harddrive. Paging is when it copies the information or process to your harddisk and marks it to be dumped from system memory if needed. Therefore if your system calls back the process it still has it in system memory, but if it doesn't and you open a new program it can dump the information quickly without having to transfer it to the disk first. This is done during your "system idle process" and in the background. If a process sits idle for too long windows will copy it over or page it to the harddisk.

The idea is that Windows tries to manage your system memory and virtual memory in such a way that if you decided to open a new program such as Photoshop you would be able to load that program into system memory so the program you are working on will be more responsive.

In other words what it appears that program is measuring is how much data is stored in your system memory and how much data is stored in your allotted paging file. Personally I have 2GB of memory and turn off my paging file altogether. If you play certain games or multitask above your system memory you'll be shooting yourself in the foot though.