Whereas working sets describe the resident pages owned by a process or the system, the page frame number (PFN) database describes the state of each page in physical memory. The page states are listed in Table 7-20.
The PFN database consists of an array of structures that represent each physical page of memory on the system. The PFN database and its relationship to page tables are shown in Figure 7-33. As this figure shows, valid PTEs point to entries in the PFN database, and the PFN database entries (for nonprototype PFNs) point back to the page table that is using them. For prototype PFNs, they point back to the prototype PTE.
Figure 7-33. Page tables and the page frame number database
Of the page states listed in Table 7-20 ...