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

Give an overview of windows 2000 file management, Give an overview of WINDO...

Give an overview of WINDOWS 2000 file management. Windows makes use of the NTFS and File Allocation Table file systems. The Older versions of the FAT file system had file name

What is paging? , What is paging? Paging is a memory management schem...

What is paging? Paging is a memory management scheme that authorizes the physical-address space of a process to be noncontiguous. Paging evades the considerable problem of fi

Why system calls have to be implementing by a interpreter, Q. What system c...

Q. What system calls have to be implementing by a command interpreter or shell in order to start a new process? Answer: In the UNIX systems a fork system call followed by an ex

Define a daemon process , A daemon is a process that removes itself from t...

A daemon is a process that removes itself from the terminal and disconnected, executes, in the background, waiting for requests and responding to them. It may also be described as

Determine the requiring variables on the scope of a thread, Determine the R...

Determine the Requiring Variables on the Scope of a Thread It is very common in server application programs to require variables on the scope of a thread. To provide such a sco

Explain tightly coupled systems and loosely coupled system, Differentiate t...

Differentiate tightly coupled systems and loosely coupled systems? Loosely coupled systems:-  Every processor has its own local memory  Every processor can communicate

Program, i need the job to be done within 3days

i need the job to be done within 3days

Explain kernel activity for ults, KERNEL ACTIVITY FOR ULTS: The kernel...

KERNEL ACTIVITY FOR ULTS: The kernel isn't aware of thread activity but it is still managing process activity. When a thread compose a system call the whole process will be bl

Operating system components, Question 1 Discuss the following with respect ...

Question 1 Discuss the following with respect to Operating Systems: Operating System Components Operating System Services Question 2 Describe the theory behind Pagin

What are the objectives and functions of operating system, What are the obj...

What are the objectives and functions of operating system? Functions of operating systems 1.      It allocates the resources and acts as a supervisor. 2.      It hides th

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