Never mention the approach I outline here to your operating system vendor. And it's probably not a good idea to mention this to operating system administrators either, unless they are also Oracle administrators. Also be aware that every operating system uses different words, terms, and algorithms. But this general three-step process provides the guidance you need when understanding if there is a memory bottleneck-excuse me, I mean memory pressure.

In memory, paging is the first line of defense. A process asks the operating system for memory (for example, issuing the C malloc call), and the operating system looks for free memory. First, the operating system looks for free memory pages or memory from other processes that have not recently been used. This is called a page fault, but not a physical page fault. (The fault part is unfortunate, but that's what it's called.)

Out-of-memory paging is the second line of defense. If the process memory is not satisfied, the operating system gets a little more aggressive. It now finds another process's memory page (which hopefully has not been used in a while) and writes or pages it out to disk onto the swap area (on Windows, that's the page file). This is known as a page out (po), or a physical page fault. Physical page faults are normal and acceptable up to a point. Your operating system administrator and experience on a specific platform will provide the best guidance.