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.



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. Does anyone know what the difference is between physical memory and the page file? And how come they can have varying amounts?

 

Physical memory is your actual system memory. Virtual memory such as your swap file is using your harddrive as additional memory. Windows is notoriously HORRIBLE at properly using the swap/paging file and physical memory. Personally I use 2GB of Corsair XMS memory and just turn the silly swap/page off.

Windows is set up in such a way to leave you with enough physical memory to keep opening new windows/programs as needed. Essentially trying to prevent you from running out of physical memory. So it will use the paging file even when not needed.

 

I'm no expert but I'll take a stab at your question.

I think you're mistaken when you say the page file is a combination of actual RAM/physical memory and the swap file that is virtual RAM on a Windows hard drive. I think that the swap file is the paging file. They are two different terms for the same thing -- a special file on the hard drive that Windows uses as virtual memory.

Thus there is no correlation at all between the numbers showing amount of physical memory in use, the total physical memory available and the swap file/paging file numbers. The two numbers for the swap file/paging file are similar to the two numbers for the physical RAM though. The first swap/paging file number shows how much storage space in the swap file/paging file is actually being used as virtual memory by the system and the second number shows the maximum amount of storage space that the swap file is set to use. That maximum limit is not equal to the amount of free space on your hard drive. It's either controlled by Windows or you can set it yourself.

If you're running XP go to the Control Panel/System/Advanced tab under and under the top section labeled "Performance" select "Settings". Click on the Advanced tab and look down at the bottom where it says "Virtual Memory." Right there it states "The paging file is an area on the hard disk that Windows uses as if it were RAM." (i.e. uses as if it were physical memory)

If you click on the "Change" button you'll see that there are options allowing you to specify the size of the Swap file or to allow Windows to manage the page/swap file, which is typically the default setting. You can also turn off the page file entirely but this isn't a good idea unless you really have plenty of RAM. For XP I think this means 2 Gigabytes of RAM (actually slightly less than 2 GB I believe). If you have that much, that's all that XP can handle and the swap file won't really add any additional functionality. But if you have less than 2 GB you're probably better off leaving the swap file alone.

If you're interested in tinkering with the size of the swap file I think there are productive ways to do so but just random tinkering isn't the best way to proceed.

I believe I've also read that you can make your system a bit faster if you have a second hard drive and put the swap file on that second hard drive. But if you're interested in doing some tweaking of your swap file I suggest you search on the web and also the forums here at MG for additional info on the topic.

Hope this is some help.

 

I suspect you can search and find additional threads discussing the swap file here at MG, but here's one to get you started:

http://forums.majorgeeks.com/showthread.php?t=114498

 

Swap and Paging are two different techniques. A swap is taking the process and moving it to say your harddrive and using your harddrive as virtual memory.

A page is slightly different. When a process in system memory isn't being used Windows will copy it to your paging file. It still keeps the copy in your system memory, but if you need that memory for something else it dumps it and if you later decide to recall the previous process it will load from the page file.

They work interchangeably, but they accomplish the same task and that is giving your system memory a breather so that you have room to store new data into system memory. The terms are often used interchangeably as well, but they technically are different.

 

While looking up something in my motherboard manual I found that the effective limit on RAM for the 32 bit version of WinXP is just under 4 GB rather than just under 2 GB as I stated in my earlier post in this thread. No idea what the theorectical limit for RAM is for 64 bit versions of XP but no doubt it's a much higher limit.

Thought I should post this correction in case someone's regretting buying 4 gigs of RAM for XP or was thinking of buying and be mislead by what I wrote earlier.

 

http://en.wikipedia.org/wiki/Windows_XP_Professional_x64_Edition Also wanted to note, disabling the page/swap file can cause some apps to crash, even if you have loads of ram, as they may be dependant on it being there.