I am measuring memory efficiency. I am talking about Virtual Memory what I want to ensure is that I can select the range of virtual addresses that a process can access like my whole process could only access virtual addresses between [0x00000000,0x000010000] for example. What I want to ensure that my multiple mallocs I will be calling will only allocate between those virtual addresses. Also: You are right that virtual page swapping is irrelevant. Sorry for misspeaking.