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

Making the transition to client - server programming, Making the Transition...

Making the Transition to Client - Server Programming Making the transition to client - server programming is a significant effort. Client - server applications must be designed

Processes and programs, Processes and Programs Process is a dynamic...

Processes and Programs Process is a dynamic entity which is a program in execution. A process is a sequence of information executions. Process exists in a limited span of t

What are files and explain the access methods for files, What are files and...

What are files and explain the access methods for files? File definition Attributes, operations and types Direct access Sequential access with diagram Other access

Defining kernel, Problem 1. What is kernel? What are the main component...

Problem 1. What is kernel? What are the main components of a kernel? Defining Kernel Explaining Main components of Kernel 2. What is mutual exclusion? What are i

Advantages and disadvantages of multiprogramming, Q. Advantages and disadva...

Q. Advantages and disadvantages of multiprogramming? Advantages 1.    High CPU utilization. 2. It appears that many programs are allotted CPU almost concurrently. D

Parent process: why not finishing and how to make finish, #include #inclu...

#include #include #include #include #include int main(void) { int pchan[2], pid, rval, cvar; char buf[20]; if (pipe(pchan) == -1){

What is an operating system?, What is an operating system? An operating...

What is an operating system? An operating system is a program that acts as a mediator between a user and the computer hardware. The function of an operating system is to provid

What are the various available scheme in ipc, Several schemes available are...

Several schemes available are as follows: Pipes : One-way communication process through which different process can interact. The problem is that the two processes could have

Explain clustered file organization, Clustered file organization A cl...

Clustered file organization A clustered file is also called a B-tree-clustered file is a tree-structured file in which records with adjacent index values are clustered toget

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