Dirty Size, VM Tracker, iPhone

My doubt is regarding iPhone "VM Tracker" memory management tool. I have been trying out this tool with my project and found that the "dirty size" column is showing 55 MB, which is quite huge. It would be great help if someone could answers the following

1. How could I see which variables are the cause of "dirty" size?
2. 32MB memory is consumed by the VM_ALLOCATE, what is this VM_AL开发者_C百科LOCATE?
3. I have used navigationcontroller in most of my programming, is it the cause of problem since it stacks all view controller inside it?

Are you running VM Tracker on the iOS Simulator or on a physical iPhone etc? The data is only useful when monitoring an iOS Device.