Explain the different page replacement policies, Computer Engineering

Assignment Help:

Explain the different page replacement policies.

Various page replacement algorithms are briefly explained below:

1. First-in, first-out

FIFO page replacement algorithm is a low-overhead algorithm. Now there the operating system maintains track of all the pages in memory in a queue, along with the most current arrival at the back, and the initial arrival in front. While a page requires to be replaced, the page at the front of the queue as the oldest page is selected.

Advantage: FIFO is intuitive and cheap.

Disadvantage:

1. Not good performs in practical application.

2. Suffers from Belady's anomaly.

2. Not recently used

NRU page replacement algorithm works at the following principle: while a page is referenced, a referenced bit is set for which page, marking this as referenced. The same, when a page is modified or written to, a modified bit is set. At an exact fixed time interval, the clock interrupt triggers and clears the referenced bit of each the pages, therefore only pages referenced inside the current clock interval are marked along with a referenced bit. When a page requires to be replaced, the operating system divides the pages in four classes:

  • Class 0: not referenced, not modified
  • Class 1: not referenced, modified
  • Class 2: referenced, not modified
  • Class 3: referenced, modified.

The Not recently used algorithm picks a random page from the lowest category for removal.

3. Optimal page replacement algorithm

The optimal page replacement algorithm (also termed as OPT) is an algorithm which works as follows:

When a page requires being swapped-in, the operating system swaps-out the page, whose subsequent use will occur farthest in the future. For illustration, a page which is not going to be used for the next 6 seconds will be swapped-out over a page which is going to be used inside the next 0.4 seconds.

Disadvantage: This algorithm can't be implemented in the common purpose operating system since this is impossible to calculate reliably how long this will be before a page is going to be used.


Related Discussions:- Explain the different page replacement policies

What is game playing ai, This covers a number of game playing methods, nota...

This covers a number of game playing methods, notably checkers and backgammon because so much good research has been completed on these problems and because so many different metho

Find the nyquist rate, Find the Nyquist rate for the following signals: (a)...

Find the Nyquist rate for the following signals: (a) x(t) = 5 sin 3000πt cos 4000πt (b) A binary channel with bit rate 36000 bps is available for PCM voice transmission. Fi

Describe about the desk top publishing, Desk Top Publishing (DTP) As wo...

Desk Top Publishing (DTP) As word processors develop increasingly more sophisticated features, differences with desk top publishing (DTP) packages becomes more and more blurred

In which network configuration all data/information pass, A distributed net...

A distributed network configuration in which all data/information pass through a central computer is (A)  Bus network                            (B) Star network (C)  Rin

What kind of system do we need to run gimp, Any system able of run Gnome 2,...

Any system able of run Gnome 2, KDE 3.2, Windows 2000, Mac OS X and later versions should be capable to run GIMP. GIMP's biggest appetite is for memory and how much you will requir

Make your simulation run faster, Ameliorating the mechanical delays of seek...

Ameliorating the mechanical delays of seeks and rottion are usually regardeed as major aspects of device drivers for disks. The simplest way for a disk device driver to service dis

Show sample instruction format of mips instruction, Q. Show Sample Instruct...

Q. Show Sample Instruction Format of MIPS instruction? Early MIPS architectures had 32-bit instructions and later versions have 64-bit implementations. The first commercial

What are the advantages of store program control, What are the Advantages o...

What are the Advantages of store program control (I) Easy to maintain (II) Easy to control (III) Wide range of services can be provided to customers (IV) Flexible

Explain dataflow computing, DATAFLOW COMPUTING A substitute to the Von ...

DATAFLOW COMPUTING A substitute to the Von Neumann model of calculation is dataflow computation model. In the dataflow model, control is tied to flow of data. Order of instruct

Artificial neural networks - artificial intelligence, Artificial Neural Net...

Artificial Neural Networks - Artificial intelligence: Decision trees, while strong, are a easy representation method. While graphical on the surface, they may be seen as disjun

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