COMPUTER ORGANIZATION AND ARCHITECTURE DESIGNING FOR PERFORMANCE NINTH EDITION

To understand the structure of the linear address, you need to know that
the Pentium II paging mechanism is actually a two-level table lookup operation.
The first level is a page directory, which contains up to 1024 entries. This splits the
4-Gbyte linear memory space into 1024 page groups, each with its own page table,
and each 4 Mbytes in length. Each page table contains up to 1024 entries; each entry
corresponds to a single 4-Kbyte page. Memory management has the option of using
one page directory for all processes, one page directory for each process, or some
combination of the two. The page directory for the current task is always in main
memory. Page tables may be in virtual memory.