Virtual memory can mean 2 things.
For a system, it's the sum of physical and swap memory size.
For an application, it the total memory allocated, regardless of it being written to or not (like an app requesting memory from OS, but not actually using it).
Please be more specific of what you want. From the 1st reading of your pots, I immediately thought about swap memory, since that can have a dramatic effect on performance and can be customized by a user.