Windows 7 - One Pagefile / Swap - Multiple operating systems

Hello!

In my first partition I have windows xp, and in the second partition windows 7.

Is it safe to use only one swap / pagefile from only one partition (first one where resides windows xp)?

My pagefile size is set to be in the first partition and at fixed size (minimum 4096 Mb maximum 4096 mb).

Or should I make/move/user a swap file from the second partition (windows 7 partition). Far as I know from my benchmarks the hardisk is faster in the first partition (first 20 GB), that would be the xp partition, fast in the second one (from 20 to 50 gb) after this the speed is decreasing.

I am using windows xp because Photoshop and some games seem's to be far more resposive and faster than in windows 7, and I use windows 7 for internet related & other stuff.

PS and some games seem to be faster because you are thin (very thin in 64 bit) in RAM

To zigzag3143

If the OP had two hard drives with the first partition of the second being used for a dedicated pagefile (as is common), is there any particular reason why a common pagefile could not be used?

You can use a single pagefile between Windows XP and Windows 7. The contents of the pagefile are wiped each time you boot into Windows. It is perfectly safe and capable.

Hi there
Note there is a difference between paging and swapping.

Swapping simply means just copying some of your current workspace out to HDD - almost like imaging your current workspace -- it's usually a fairly expensive and time consuming process - and EXTREMELY I/O bound.

Paging on the other hand is just a mechanism mapping memory addresses to actual addresses -- when an application needs more memory say it wants an extra 120 MB of real memory which isn't available -- Windows goes to see what chunks of memory were last recently used (known as LRU) and writes these addresses with their contents to the paging file.
The Windows Task dispatcher then allocates this chunk of memory to the application which can use it at will.

Paging algorithms are often very complex to get the OS to perform efficiently -- the LRU (last recently used) algorithm is used fairly often in OS design as it's relatively (and I say relatively since this whole topic is a complex subject) easy to implement.

What happens with swapping is when there isn't enough memory left even for the paging system to allocate properly so a whole application will be swapped out to disk - including temprary storage areas and paging data -- often a long I/O process.

If this application is needed again quickly the whole process is reveresed with another application having to be swapped out.

This phenomonenon is known as thrashing and you will immediately notice when it happens -- the disk HDD light will be permaanently on and the computer will seem as if its locked ---occurs when you don't have much ram and are trying to run too many applications at once.

Windows store swapping in the page file too so swapping here is DOUBLY expensive if it occurs --some os'es at least keep separate swap and page files on different drives.

the Pagefile.sys for XP / Windows 7 will be overwritten each time by each os at boot if you have them on different partitions / drives to the OS so no problems.

Running multiple OS'es concurrently as VM's won't cause any problems either since each VM will have its own set of virtual disks too. You will only hose it up if you try and use the same RAW DISKS for two concurrently running VM's.

Cheers
jimbo

I'll probably have to get around to dual OS operation when my old XP system finally kicks the bucket - have too many useful programs that will not run on Windows 7. Either that or the virtual XP approach.