venu chowdary

 Profile Answers by venu chowdary 

• Apr 6th, 2010

 

A page is a fixed-length block of memory that is used as a unit of transfer between physical memory and external storage like a disk, and a page fault is an interrupt (or exception) to the software raised by the hardware, when a program accesses a page that is mapped in address space, but not loaded in physical memory. Actually, page fault can occur in 2 ways these are mainly:

Hardware generates a page fault:
The page corresponding to the requested address is not loaded in memory.
The page corresponding to the memory address accessed is loaded, but its present status is not updated in hardware.

Protection fault is generated for page:
The page is not part of the program, and so is not mapped in program memory.
The program does not have sufficient privileges to read or write the page.
The page access is legal, but it is mapped with demand paging.