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

Define a program that is in execution is known as, Define a program in exec...

Define a program in execution is known as A program in execution is known as a process

In JavaScript, Ask quesIn JavaScript, what is event handling tion #Minimum ...

Ask quesIn JavaScript, what is event handling tion #Minimum 100 words accepted#

Starvation, what do you mean by starvation?explain in detail

what do you mean by starvation?explain in detail

SCAN SHUDULLING, EXPLAIN THE SCAN SHUDDULING WITH DIAGRAM

EXPLAIN THE SCAN SHUDDULING WITH DIAGRAM

Peripharal device, 50 peripharal device name ,diagram and uses

50 peripharal device name ,diagram and uses

Define abbreviation of sstf, SSTF stands for Abbreviation of SSTF is S...

SSTF stands for Abbreviation of SSTF is Shortest-Seek-time-first scheduling

Write a linux script to add name in class list, For this exercise I wanted ...

For this exercise I wanted to give you some real-world examples of useful bash scripts. Therefore, you will write a couple of scripts that I actually use in my teaching to automate

Batch system, what is a batch system give me answer in simple words so that...

what is a batch system give me answer in simple words so that i can understand

What are the different file operations?, What are the different file operat...

What are the different file operations? Create : - Space for the file in the file system update directory table. Write : - file name and data to be written is

Explain a working of file control block, Explain a working of file control ...

Explain a working of file control block A file control block (FCB) has information about the file, containing ownership, permission, and location of the file contents. The log

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