Virtual Memory

In Windows XP, I got a message that virutal memory is low, and something about the system will try to adjust. What does it mean, and what can I do about it?

 

Windows uses a file to simulate having more memory than physically available in the system. To see/adjust the VM settings, go to (right click)My Computer -> Properties -> Advanced -> Performance(Settings) -> Advanced. There you will see your VM settings and be able to click the Change button. The best option for novices is to set it to "System managed size" and then click Set. That way Windows will be able to grow the VM file as needed. Changing the setting might force you to reboot. Before trying to mess with it, just keep going until you hit the error again.

 

You'll only have to reboot if you try to shrink or eliminate the pagefile. Otherwise, you're set. You can get an idea of how much memory (page + real) you have free by looking at the memory graph in the task manager.

 

Or upgrade your ram

how much do you have?

 

I have 512 mb of ram. That is the max for this computer.

 

A sign that you have out run your computer, may be time for a new one. XP by default allocate reasonable page file to supplement physical RAM size you have and if it needs to extend that, it means your working set is larger than desirable. If this is an occasional thing(or may be some buggy program like firefox), that is fine. But otherwise, you would see the disk keep on spinning and the computer becomes very slow.

 

How much virtual memory are you Vista users allocating?

How much virtual memory should I allocate for my machine? See my signature for specifications of my FZ160.

Thanks in advance.

 

well i read somehwere to allocate about 1.5x of your system ram to VM...

so if you have 2gb RAM, put VM to 3gb...

 

Enough.

Terrible advice. I've heard the same rumor, and it makes absolutely zero sense.
It works the opposite way.
The less RAM you have, the bigger pagefile you need. If you have 4GB RAM, you might be able to get by without a pagefile.

If you have 512MB RAM, you can in theory end up needing 3.5GB pagefile.

Try making that fit into the 1.5x theory.

It's actually quite simple.
All the applications you've got running use virtual memory. Virtual memory is a combination of physical RAM and the pagefile. Windows decides which data goes in physical RAM, and which goes to the pagefile. The application is not away of that. It just requests the memory it needs.

So here's the one and only true equation for "how big should my pagefile be":
RAM + pagefile = enough
or
pagefile = enough - RAM

Where RAM is the amount of physical memory on your system, and enough is the largest amount of memory you're ever going to need at any one given time.

And what do you lose by making the pagefile bigger?
Harddrive space. Nothing else. Performance does not suffer. There's absolutely no reason not to make the pagefile big enough to ensure you don't run out of memory.

 

Well like i said, i only read it somewhere so i wasnt 100% sure aswell... infact i think i read it on this forum somewhere...

well i think that clears things up

 

Running Vista I have approximately 2800MB of HDD space allocated for Virtual Memory along with 2.5GB of RAM. Everything seems to run along rather merrily.

 

umm, windows needs some pagefile to be happy. At least the same amount of physical RAM you have. Windows is always paging. It gets all unhappy when there's no pagefile.

Yea, I've tried it. Run the benchies and stopwatch. Windows needs some pagefile.

Rule of thumb is 2x the physical ram. However when the physical get up there (2GB or more) you can reduce this.

 

I did say might
Of course, the specific OS might behave a bit quirky in some cases, but that doesn't change the basic rule. Your RAM + pagefile combined has to be big enough.

Thank you for repeating the same rumor I just tried to get rid of.
1.5X, 2X, 14.932X your RAM, it is not true, no matter the multiplier.

It is the exact opposite. The LESS RAM you have, the MORE pagefile you need.

Pretending that "<insert number> times your RAM is ideal" does nothing more than confuse and mislead people, and lead them to unstable computers. Yay. Congratulations.

So can we please stop repeating this nonsense now?

 

I'll typically tell people to use about a 1-1.5GB pagefile. If you're using that much of your pagefile, your system has bogged down to nothing if you don't have much memory, or it's just supporting your normal operations if you have a lot of memory (2GB or so). Tends to be pretty safe. 1.5x was a valid rule of thumb when system memory sizes were between 64 and 256MB of RAM, but now? All it'll do is eat up disk space unnecessarily.

That said, there ARE reasons to have a larger pagefile, but even gamers won't run into those. You pretty much have to be seriously using the machine, and not worrying a lot about real-time performance, to run into needing a larger pagefile.

Yup. All that you're missing is disk space that could be used for data instead of an empty pagefile. You're basically setting aside 1.5GB (or more) of your hard drive as completely unused space, for no reason. It won't hurt performance, but that's another game you could install and still have room to defrag...

 

Why all this talk about specifying the pagefile size at all? Why not just let the OS maintain the size itself? Isn't that what the "system managed size" option is for? Yes, I know doing a setting it to NO pagefile, defragging and then setting it to some specific size results in a contiguous pagefile. I've done that, before but saw ZERO difference in performance. The "system managed size" has worked fine for me and on the off chance I overload things the system can easily create more virtual memory space. The usual, "your mileage may vary" applies of course.

Gary