I'm working on Windows 7 and have just installed XP mode. I've run many program on the XP VM.

When I launch the VM my Windows 7 memory usage is some 1600M. Once the VM is running I go up to 2240 - A 640M difference.

Why is this happening?

I am viewing the running processes list (all users) and the VM entry states 17M.

Any insight is appreciated.

  • How are you measuring the memory usage? By what program, and what reading? Also, how much memory have you allocated for the VM? – Breakthrough Feb 25 '11 at 19:19

I tent to use Process Explorer to answer and that sort of questions:


Or even use vadump



Most modern operating systems use a disk page cache, which stores frequently or recently used information from your hard drive in memory to speed up future access. When you start Windows XP in Virtual PC, Windows 7 loads many of the files Windows XP needs to run into its disk cache so the VM runs faster.

If you need the memory for something else, Windows will automatically free it and make it available to other programs, so there is no need for concern.


It is HIGHLY unlikely that the virtual machine is only taking 17Mb, it will have another process running. I think you are just looking at the GUI process for the VM.

I would use Microsoft / Sysinternals Process Explorer, or just make sure you tick the "Show processes from all users" in the bottom left hand corner of Task Manager.

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