Lru implementation details, Operating System

Assignment Help:

Now, let us discuss two related algorithms for deciding which pages to evict. The clock algorithm is one of the most popular choices. It works by keeping frames in a circular structure. (Note that this circle may be very large: a 32-bit machine with 4k pages can have up to 220  1 million frames.) When a page fault occurs, it checks the reference bit of the next frame. If that bit is zero, it evicts that page and sets its bit to 1; if the reference bit is 1, the algorithm sets the bit to 0 and advances the pointer to next frame. 

An implementation which is often used in real operating systems is a segmented queue. This type of algorithm divides all existing pages into two sets of pages. The most-active one-third of all pages use a clock algorithm. After that, pages that are evicted out of the clock are moved to a "uncommon" linked list, in which we use exact LRU. This way, we approximate LRU for the frequently-referenced pages (1/3 of the page frames - fast clock algorithm), and at the same time use exact LRU on the infrequently accessed pages (2/3 of all page frames). Since the pages in the uncommon list are not accessed very frequently, it is okay if their accesses are a little slower due to some pointer manipulation.


Related Discussions:- Lru implementation details

Windows Resources on a Network, VoIP (Voice over Internet Protocol), also c...

VoIP (Voice over Internet Protocol), also called Internet telephone, was once a novelty on the Internet, but not very useful because of all the problems with poor voice quality and

Why do systems stay track of the type of a file, Q. Why do some systems sta...

Q. Why do some systems stay track of the type of a file while others leave it to the user or simply don't implement multiple file types? Which system is "better?" Answer: A f

VB. Net & XML, Write a XML with database with book details (BOOK ID, Title,...

Write a XML with database with book details (BOOK ID, Title, Author, subject, publisher year, language, vendor, and price)

What are the various scheduling criteria for cpu scheduling, What are the v...

What are the various scheduling criteria for CPU scheduling? The various scheduling criteria are CPU utilization

Data races, Research the phenomenon of data races. Give an example of how...

Research the phenomenon of data races. Give an example of how an unprotected data race can give rise to data inconsistency. How do OpenMP and Cilk resolve this problem? Data

Producer - consumer synchronization, This assignment is based on Programmin...

This assignment is based on Programming Project 6.40 in Silbershatz. Implement the ProducerXConsumer program according to the instructions for Project 6.40 for both Linux and Win32

Vehicle tasks using semaphores, Gopher Gallery consists of a shopping mall ...

Gopher Gallery consists of a shopping mall and a cart ride that covers  the 150 acre habitat. There are m visitors and n single-person vehicles. Visitors  stroll around the mall at

Binary and data representation, Computing uses three number bases:- Binary ...

Computing uses three number bases:- Binary (base 2), Octal (base 8) and Hexadecimal (base 16). Binary has been described before, although various catchphrases are used to describe

Explain lru approximation page replacement in detail, LRU approximation pag...

LRU approximation page replacement In this we utilize the reference bit associated with the page entry to choose a page to be removed. The various algorithms used for the imp

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd