Virtual memory mysteries in XP...

[Grakatt]

Helloes. I have a problem with configuring the swap-file in Windows XP.
I have three partitions. Two have 'no swapfile' selected, and for one I've set the file to 512MB (borders 512 and 512).
Yet, on the bottom of the virtual memory-screen, it says 'recomended : 766MB, current swapfile: 767MB' and indeed I see when running the defragmenter that the size of the swapfile is 767MB (and 600 fragments just after defragmentation).
What do?

 

[tjaisv]

You shouldn't have to change the size of the swapfile. Windows XP already manages it well enough, just leave it default.

But it's good that you put the swapfile on its own partition. It'll always be fast and unfragmented as long as you don't start using that partition for files.

 

[Grakatt]

Heh, the swapfile lies on my windows-partition....anyway, I prefer to choose the size of the swapfile, but now XP has removed my influence over it, or so it seems..

 

[dnuggett]

You can adjust the size of the swap file by right clicking on My Computer to bring up properties. Under the advanced tab use the settings option in the performance section and then go to the advanced tab in the performance options menu. Use the change button in the virtual memeory section. Click the customize size button. Set the initial size and and maximum size identical. Generally you want the swap to be 2x the amount of RAM. Click OK all the way through and it will be set at the same size. XP now has no influence on your swap file size.

 

[Grakatt]

What? I'm sorry, but did you even read my question?

 

[kylef]

I'm not completely up to speed on how NT/XP chooses a swap file size, but generally 150% of your system RAM amount is considered a minimum. My laptop here has 256 megs of RAM and a 384 meg minimum swapfile, for instance.

A swapfile is not an optional component, because it is where Windows stores pages of virtual memory that have been evicted from physical RAM for whatever reason. It is impossible (and impractical) to page everything into physical memory at all times.

Just to give you an idea of how many page faults are actually occuring on the system (during a page fault, the OS is loading a page of virtual memory from the swap file into physical RAM) you can bring up Task Manager and click on the "View->Select Columns..." menu option. Make sure that "Page Faults" is checked for display. You will probably see tens of thousands of them, depending on how much activity your system has seen. Each page fault represents loading 4kB of memory from the swap file, so I'll let you do the math...

 

[Grakatt]

I'm speechless.
Did you read my question??

 

[dnuggett]

to choose the size of the swapfile, but now XP has removed my influence over it, or so it seems..

I'm speechless as well. Your above statement suggests that you were having problems setting the swapfile size because XP "removed your influence over it". That's why I responded the way I did. How about instead of asking if we read your question you reword it so someone can understand what you are asking. Or wait until someone comes along who can interpret what you are saying. That may happen soon, but it ain't happened yet.

 

[rbV5]

Did you remember to "set" it first.

 

[kylef]

Originally posted by: Grakatt
I'm speechless.
Did you read my question??

Yes I did, and I apologize if I have somehow offended you. Do you have 512 megabytes of RAM? If so, I was trying to explain why NT had picked 768 (150% of physical RAM size). I'm sorry if that was not clear.

NT requires a swapfile size GREATER THAN the amount of physical memory in your system so that it can handle memory dumps correctly in certain error situations. Try setting the size to 520 or something a little above the actual size of your physical memory.