The Unabridged Pentium 4 IA32 Processor Genealogy

Three Possible Page Lookup Methods

When a 32-bit linear memory address is submitted to the Paging Unit, the Paging Unit must somehow scan the directory in memory to determine where the page of information currently resides either in physical memory or on a mass storage device. The sections that follow describe three possible methods that the processor's Paging Unit could use to perform the directory scan.

First Method: Sequential Scan through a Large Table

Using this method, the Paging Unit starts at the first directory entry and compares the target linear address to every entry looking for a match. If the last entry is reached without a match, the page isn't currently in memory. This method has the following characteristics:

• Each entry would ...