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

Backup and recovery, what is it all about? why do we need? what are the typ...

what is it all about? why do we need? what are the types of backup? how is it done in unix?

Linux kernel components, Example 1.  The diagram illustrating the data stru...

Example 1.  The diagram illustrating the data structures of in-memory VFS objects and on-disk objects and their relationships on slide 24 of the lecture notes OSD.4. This diagram i

Explain process termination - operating system, Process termination A p...

Process termination A process terminates when it finishes implementing its final statement and asks the operating system to delete it by using the exit system call. At that tim

Define a linker program, Define a linker program  A linker program lin...

Define a linker program  A linker program links the program along with other programs required for its execution.

Subject: system analysis (2000 word), Overview: In this assignment, you are...

Overview: In this assignment, you are going to perform a system analysis and design of a membership and facility management system of a gymnasium of given case study Task: You are

Explain about time sharing systems, Q. Explain about Time Sharing Systems? ...

Q. Explain about Time Sharing Systems? Time Sharing Systems Multi-programmed batched systems provide an environment where various system resources (for illustration CP

Define the conditions of deadlock prevention, What are the four necessary c...

What are the four necessary conditions of deadlock prevention?       Ans:  Four essential conditions for deadlock prevention: a. The meaning of removing the mutual exclusio

Semaphore, define semaphore. how can we use semaphore to deal with n-proces...

define semaphore. how can we use semaphore to deal with n-process critical section problem.

Nested Macro calls, . Nested Macro calls are expanded using the

. Nested Macro calls are expanded using the

Rf, whta is an operating system ? what sorts services are provided by an op...

whta is an operating system ? what sorts services are provided by an operating system ?

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