Understanding the Linux® Virtual Memory Manager

Chapter 11. Swap Management

Just as Linux uses free memory for purposes such as buffering data from disk, there eventually is a need to free up private or anonymous pages used by a process. These pages, unlike those backed by a file on disk, cannot be simply discarded to be read in later. Instead they have to be carefully copied to backing storage, sometimes called the swap area. This chapter details how Linux uses and manages its backing storage.

Strictly speaking, Linux does not swap because “swapping” refers to coping an entire process address space to disk and “paging” to copying out individual pages. Linux actually implements paging as modern hardware supports it, but traditionally has called it swapping in discussions and documentation. To ...