OSX memory management

Question for the people who know more about this then I do (not all that hard )

Why is LR (or PS for that matter) using virtual memory when there's plenty of "real" memory available?

I'm no expert at Mac innards as I am with PC/Win, but from what I remember reading is this is not the actual size of the VM but what has been allocated. If you go look at the swap location you'll only see 50-100MB of usage, not 12,65GB. I have Leopard and Intel and it says VM Size: 53,03GB but only 235KB Page Ins and 76MB Page Outs. When I look at the private folder it's only 54MB big. I have Compressor, Final Cut Pro, and QMaster going - all very very memory intensive programs and still have 2GB free memory. OSX is just allocating space virtually I believe.

Yup, allocation.

But why would it allocate even 1Mb if there's still 4Gb of RAM inactive (has been used by some software earlier on, isn't used anymore, but isn't "flushed" yet if I have that right?)

René Damkot wrote in post #7252330
But why would it allocate even 1Mb if there's still 4Gb of RAM inactive (has been used by some software earlier on, isn't used anymore, but isn't "flushed" yet if I have that right?)

It can get pretty complex - the short answer is that virtual memory really doesn't matter all that much in OS X unless you start getting heavy page hits. Here is some info to read on more detailed information on OS X memory management:

http://developer.apple​.com …Articles/AboutM​emory.html

Duh. Why didn't I think of looking there?
Thanks!