PAGE REPLACEMENT ALGORITHMS in OS

PAGE REPLACEMENT ALGORITHMS
In general, we want a page replacement algorithm with the lowest page-fault rate.
We evaluate an algorithm by running it on a particular string of memory references and computing the number of page faults on that string.
To determine the number of page faults for a particular reference string and page replacement algorithm, we also need to know the number of page frames available.
Obviously, as the number of frames available increases, the number of page faults decreases.


(Expected relationship between number of free frames allocated to a process and the number of page faults caused by it).

FIFO Page Replacement
The simplest page-replacement algorithm is a FIFO algorithm. 
When a page must be replaced, the oldest page is chosen.
We can create a FIFO queue to hold all pages in memory. We replace the page at the head of the queue. When a page is brought into memory we insert t at the tail of the queue. 
Example: consider the reference string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1



Comments

Post a Comment

Popular Posts

Data And Information

Data And Information Data  representing quantities, characters, or symbols on which operations are performed by a  computer.  D ata is not  information . Data requires interpretation to become information. To translate data to information, there must be several known factors considered. The factors involved are determined by the creator of the data and the desired information. In simple or according to me data is anything which we give computer in input. Information  is stimuli that have to mean in some context for its receiver. When  information  is entered into and stored in a  computer , it is generally referred to as data. After processing (such as formatting and printing), output data can again be perceived as  information  . Anything in computer output in any form (audio, video, text ) can be called as Information.
Read more

How to approve adsense account 2020

Image
How to approve adsense account 2020 Hi here i am sharing best trick of the year how to approve adsense, i just got approved by adsesnse in just 20 hours.  Adsense also called Google Adsense is best and oldest of  online earning  it is an advertising service by Google.  The Adsense is designed for website publishers and blogger’s who want to earn money by displaying targeted text, video or image advertisements on their website pages. Earning money depends upon site visitors, views (impressions) and clicks on ads nature of Ads. How to approve adsense account 2020 CPC etc SEO terms, before reading this article make sure your website or Blog has 3 main pages, 1- HOME, 2- Blog   3- About, 4 -Contact Us if you don’t have these designs these pages with appropriate information and then apply my given tricks to approve adsense. The advertisements are controlled and managed by Google. Web publishers simply need to create a free AdSense account and copy and paste provided ad code to display the a
Read more

Best website hosting providers with pros and cons

Image
Finding The good web hosting service take a lot of time and money. To take dicision. To justify the dicision we’ve signed up with, tested and compared more than 30 different web hosting provider companies. This means that we also have performance data of the web hosting service. Uptime and load time  are two of the most important factors when choosing a web host (next to their cost). Here is our review process in detail: We sign up with the web hosting plan offered by the hosting service We set up a blank WordPress website We monitor their performance, such as uptime and load time We check their features, limitations, pricing and customer support We publish the review ( updating once a year ) All of our hosting reviews are based on each web host’s average speed (load time), uptime and cost. If you want more detailed data, see our data page or this spreadsheet. 10 Best Hosting Services for New Websites Below is a list of 10 best website hosting providers that we’ve found reliable and wi
Read more