Prior to 2.6.31, the kernel simply used two lists. New pages were brought into the recency list, and if they were referenced for a second time, these pages were promoted to the frequency list.

Similarly, if the recency list needed more memory, pages in the frequency list were demoted to it (giving these pages a second chance), and eventually removed from the cache.

In 2.6.31, a change was checked in to better handle cases such as nightly backups evicting interactive user program data. With this change, the frequency list's minimum size was fixed, and if the size dropped down to 50%, pages were no longer demoted from it.