[Chris R]

I get a window that pops up when my computer sits un-attended during the day that claims im "Low on virtual memory" and that windows is upgrading the size and some applications may not work or something like this.

Can someone tell me what the deal is? What is virtual memory? I have no idea why I would be low on it in the first place.

 

[MadMarv]

Your computer has specifc, very fast memory chips. They come in different sizes, and the more the better. They are much faster than hard drives. Applications run better, so on and so forth, graphics programs go amazingly faster, etc.
Virtual memory essentially takes a part of your hard drive and uses it as "memory." Its slow- like regular hard drive access. It is usually needed when your computer has insufficent actual memory. It was more popular in the early 90s when memory chips were still very expensive. Your hard drive stores data- programs, documents, whatever. Memory is quick, transient bits of information the computer finds relevant and wants to access quickly, often repeatedly. Virtual memory just mimics (badly) real memory by using a chunk of your hard drive as pseudo-memory.
I'm not sure what version of windows you are using, but (I'm more familiar with macs anyway), all of the earlier versions of windows had kooky memory setups that were a layover from the DOS days.
Expanding virtual memory shouldn't hurt anything, but its pretty darn slow.
A modern computer should have at least 256mb of real memory, that is really the bare minimum, 512mb is better, 1 gig + if you want your machine to be a smooth runner.

matt

 

[vrooom3440]

Virtual memory arises from the what we in the business call the "memory heirarchy". The basic idea is that as a type of memory gets faster it also gets more expensive so you have less of it. Top of the pyramid are "registers" in the CPU (128 bytes), then the CPUs "cache" (256KB), possibly a "L2 cache" (512KB), random access memroy "RAM" (1GB), hard disk (120GB), and finally offline storage (CR ROMs and such). A lot of time and energy in computer systems is spent in moving data between these different types of memory.

With virtual memory your computer pretends it has an almost infinite amount of main memory RAM in it. But there is a table in the hardware to keep track of what is really in RAM, everything else is on the hard disk. When you go to access something that is not in RAM, it has to take something out of RAM and put it on the hard disk and then read the data into RAM from the hard disk. This is called "swap" and sometimes the space used for this on the hard disk is called "swap space". The swap space in windows is pre-configured by one of the control panels (I forget which one... I'm more of a Unix guy).

You may run low on virtual memory if you have insufficient space pre-configured/allocated and/or you run too many programs at the same time. Some background activities, like screen savers, also like to consume virtual memory. Do you have any freebie software, screen savers in particular, that you are running? Might be the culprit.

 

[Finally]

If your running out of memory, real or virtual, while the system is sitting unattended then you have a problem. You probably have a program running that has a 'memory leak'. It grabs some memory to do something then does not free it up. Next time it wants to do the same thing it grabs more memory, etc. Run task manager and look at the amount of memory being used by the different processes running. One of them is out of control and sucking up more resources than it needs.

 

[Gary S]

Reboot. Windows has always had memory leaks, and most likely it always will. Reboot often and vigorously and your computer will work better.

 

[GWL]

Are you online when this happens? It could be adware.

 

[Olle]

Hit "ctrl-alt-delete" and check the performance in the task manager. We had a virus at the office a while ago, and it hogged pretty much all of the processor and memory, and made that message pop up frequently.

If memory and/or processor capacity is peaked out, I would definitely run a virus/adware check.