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LRU Page Replacement Program in C++[How to]

<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 style="text-align: center;">
<span style="background-color: white; color: #3d85c6; font-family: Trebuchet MS, sans-serif;">Least Recently Used  Page Replacement</span></h2>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Goal:- </span>Program for LRU page replacement Method.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Method:-  </span>Replace the page that has not been used for the longest period of time.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Explanation:- </span>As we seen in <a href="http://codieehome.blogspot.in/2013/10/program-for-fifo-page-replacement.html" target="_blank"><span class="Apple-style-span" style="color: red;"><u>FIFO page Replacement</u></span></a> Algorithm the problem is Belady's Anomaly and this lead us to discovery of an <a href="http://codieehome.blogspot.in/2014/12/optimal-page-replacement-program-in.html" target="_blank"><span class="Apple-style-span" style="color: red;"><u>Optimal Page Replacement</u></span></a> method that will have minimum page fault rate.But the problem in Optimal Page Replacement is that it requires the future knowledge. So in the place of optimal we can take a approximation of optimal in which we look for the pages that has not been used for a long time and predict that they will not be used in near future.</span></span></h3>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">So whenever a replacement request comes then we replace the new page with the page which has not been used for a long time and this method page replacement is known as Least Recently used(LRU) method.</span></h3>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">For evaluating an algorithm we take a particular string of memory references ,called<span style="color: red;"> reference string</span>.</span></h3>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">The LRU method is often used and considered to be good.</span></h3>
<div>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">The problem with this algorithm that how to implement LRU and there are several methods of implementing LRU. To know you can check my post(about to come).</span></span></h3>
</div>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="color: red; font-weight: normal;">Page Fault:- </span><span style="font-weight: normal;"> Page Fault is a interrput that occurs when a program request page that is not in real memory.Then this interrput sends signal to OS to fetch that page from Virtual memory and load it into RAM.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">**Program explained here counts the no. of page fault occurs  when a input reference string is implemented onto Memory according to LRU replacement method.</span></span></h3>
<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Example:-</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">               </span>Reference string- 7,0,1,2,0,3,0,4</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">                 No. of frames: 3</span></span></h3>
<h3>
<table align="center" border="1" cellpadding="10"><tbody>
<tr>   <th rowspan="2"><h3>
<span style="font-family: Trebuchet MS, sans-serif;">Frame NO.</span></h3>
</th>   <th colspan="9"><h3>
<span style="font-family: Trebuchet MS, sans-serif;">Reference String(Page Values)</span></h3>
</th> </tr>
<tr>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">Initially</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">7</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">1</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">2</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">3</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">4</span></h3>
</th> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">2</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">4</span></h3>
</td> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>    <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">3</span></h3>
</td>    <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="color: red; font-family: 'Trebuchet MS', sans-serif;">3</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">3</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">3</span></h3>
</td> </tr>
</tbody></table>
</h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">When any page value already presented in frames then no page fault will occur.</span></span></h3>
<h3 style="text-align: left;">
</h3>
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<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Program:-</span></span></h3>
<span style="font-size: 12px;"><br />
<script class="brush:java" type="syntaxhighlighter">
#include<iostream>
using namespace std;
#include<conio.h>
int main()
 {
          int nop,nof,page[20],i,count=0;
          cout<<"\n\tEnter the No. of Pages:";
          cin>>nop;  //Store the no of Pages
          cout<<"\n\t Enter the Reference String:";
          for(i=0;i<nop;i++)
          {
          cout<<"\t";
          cin>>page[i]; //Store the pages
          }
          
          cout<<"\n\t Enter the No of frames:-";
          cin>>nof;
          int frame[nof],fcount[nof];
          for(i=0;i<nof;i++)
          {
          frame[i]=-1; //Store the frames
          fcount[i]=0; //Track when the page is last used
          }
          i=0;
          while(i<nop)
          {
            int j=0,flag=0;
            while(j<nof)
            {
               if(page[i]==frame[j]){  //Checking whether page already exist in frames or not
               flag=1;
               fcount[j]=i+1;
               }
               j++;
            }    
            j=0;   
            cout<<"\n\t**************************************\n";
            cout<<"\t"<<page[i]<<"-->";    
            if(flag==0)
            {
             int min=0,k=0;
              while(k<nof-1)
                {
                 
                  if(fcount[min]>fcount[k+1]) //Calculating the page which is least recently used
                    min=k+1;
                  k++;
                }
               frame[min]=page[i]; //Replacing it
               fcount[min]=i+1;    //Increasing the time 
               count++;           //counting Page Fault
            
           
            while(j<nof)
            {
               cout<<"\t|"<<frame[j]<<"|";
               j++;
            }
            
             }
           i++;  
            
          }
          cout<<"\n\t**************************************\n";
          cout<<"\n\tPage Fault is:"<<count;
          getch();
          return 0;
}        
      
</script>
</span>

<br />
<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Output:-<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTroGSSZRAzN7XVNz-ZIv8EH7p6-MiJpFMxICx9unC1uUutG0eO5PHz9fn4uaI_1xmh_t60MCATjaQEFHfB3z1_OJe7RB2OcUprGGTzDbA1ArwbNcrtiqIMY08xqy0troHyzZ3cJguR6g1/s1600/LRU.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTroGSSZRAzN7XVNz-ZIv8EH7p6-MiJpFMxICx9unC1uUutG0eO5PHz9fn4uaI_1xmh_t60MCATjaQEFHfB3z1_OJe7RB2OcUprGGTzDbA1ArwbNcrtiqIMY08xqy0troHyzZ3cJguR6g1/s1600/LRU.png" /></a></div>
</span></span></h3>
<div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">
</span></span></div>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">
</span></span></h3>
<div>
<h3 style="background-color: white; color: #333333; font-family: Bitter, serif, sans-serif; font-weight: normal; margin: 0px 0px 10px;">
<span style="font-size: large;"><span style="color: red; line-height: 19.1875px;">If you want to share more information about topic discussed above or find anything incorrect Please do comments.</span>  </span></h3>
</div>
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LRU Page Replacement Program in C++[How to]

Least Recently Used Page Replacement Goal:- Program for LRU page replacement Method. Method:- Replace the page that has not been us...

+ Read more »

Optimal Page Replacement Program in C++[How to]

<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 style="text-align: center;">
<span style="background-color: white; color: #3d85c6; font-family: Trebuchet MS, sans-serif;">Optimal Page Replacement</span></h2>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Goal:- </span>Program for Optimal page replacement Method.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Method:-  </span>Replace the page that will not be used for the longest period of time.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Explanation:- </span>As we seen in <a href="http://codieehome.blogspot.in/2013/10/program-for-fifo-page-replacement.html" target="_blank"><span class="Apple-style-span" style="color: red;"><u>FIFO page Replacement</u></span></a> Algorithm the problem is Belady's Anomaly and this lead us to discovery of an algorithm that will have minimum page fault rate.The search ends at Optimal Page Replacement.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Optimal Page replacement algorithm will never suffer from Belady's Anomaly.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Use of this algorithm guarantees the lowest page fault rate for fixed no. of frames.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">For evaluating an algorithm we take a particular string of memory references ,called<span style="color: red;"> reference string</span>.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">In Optimal page replacement algorithm- for each page we track the time when it was brought into the memory and when any replacement request comes then we look for the page which is not going to be used in next future. </span></span></h3>
<div>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">The problem with this algorithm that it is difficult to implement because it requires the future knowledge of reference string.<u><a href="http://codieehome.blogspot.in/2014/12/lru-page-replacement-program-in-chow-to.html" target="_blank"><span class="Apple-style-span" style="color: red;">(How LRU solve this problem check here?)</span></a></u></span></span></h3>
</div>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="color: red; font-weight: normal;">Page Fault:- </span><span style="font-weight: normal;"> Page Fault is a interrput that occurs when a program request page that is not in real memory.Then this interrput sends signal to OS to fetch that page from Virtual memory and load it into RAM.</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">**Program explained here counts the no. of page fault occurs  when a input reference string is implemented onto Memory according to optimal replacement method.</span></span></h3>
<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Example:-</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">               </span>Reference string- 7,0,1,2,0,3,0,4</span></span></h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">                 No. of frames: 3</span></span></h3>
<h3>
<table align="center" border="1" cellpadding="10"><tbody>
<tr>   <th rowspan="2"><h3>
<span style="font-family: Trebuchet MS, sans-serif;">Frame NO.</span></h3>
</th>   <th colspan="9"><h3>
<span style="font-family: Trebuchet MS, sans-serif;">Reference String(Page Values)</span></h3>
</th> </tr>
<tr>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">Initially</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">7</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">1</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">2</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">3</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</th>   <th><h3>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">4</span></h3>
</th> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">7</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="color: red; font-family: 'Trebuchet MS', sans-serif;">3</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">3</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">4</span></h3>
</td> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">2</span></h3>
</td>    <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">0</span></h3>
</td> </tr>
<tr>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">3</span></h3>
</td>    <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3>
</td>   <td><h3>
<span style="color: red; font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td>   <td><h3>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">1</span></h3>
</td>   <td><h3>
<span style="font-family: Trebuchet MS, sans-serif;">1</span></h3>
</td> </tr>
</tbody></table>
</h3>
<h3 style="text-align: left;">
<span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">When any page value already presented in frames then no page fault will occur.</span></span></h3>
<h3 style="text-align: left;">
</h3>
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<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Program:-</span></span></h3>
<script class="brush:java" type="syntaxhighlighter">
#include<iostream>
using namespace std;
#include<conio.h>
int main()
 {
          int nop,nof,page[20],i,count=0;
          cout<<"\n\tEnter the No. of Pages:";
          cin>>nop;          //Store the no of pages
          cout<<"\n\t Enter the Reference String:";
          for(i=0;i<nop;i++)
          {
          cout<<"\t";
          cin>>page[i]; //Array for Storing Reference String
          }
          
          cout<<"\n\t Enter the No of frames:-";
          cin>>nof;
          int frame[nof],fcount[nof];
          for(i=0;i<nof;i++)
          {
          frame[i]=-1;  //Frame Array
          fcount[i]=0;  // Track the next Availability of frames
          }
          i=0;
          while(i<nop)
          {
            int j=0,flag=0;
            while(j<nof)
            {
               if(page[i]==frame[j]){ // Checking Whether the Page is Already in frame or not
               flag=1;
               }
               j++;
            }    
            j=0;   
            cout<<"\n\t**************************************\n";
            cout<<"\t"<<page[i]<<"-->";    
            if(flag==0)
            {
              if(i>=nof)
              {
             int max=0,k=0;
             while(k<nof)
             {
                int dist=0,j1=i+1;
                while(j1<nop)
                {
                if(frame[k]!=page[j1])  //Calculating Distances of pages that are in the frame to their next occurence
                dist++;
                else
                { 
                break;
                }
                j1++;
                }
               fcount[k]=dist; //Storing Distances into array
              k++;   
             }            
             k=0;
              while(k<nof-1)
                {
                 
                  if(fcount[max]<fcount[k+1]) //Finding out the maxximum distance
                    max=k+1;
                  k++;
                }
               frame[max]=page[i];   
             } 
             else {
                  frame[i%nof]=page[i];
                  }
               count++;  // Increasing Page Fault.
            
           
            while(j<nof)
            {
               cout<<"\t|"<<frame[j]<<"|";
               j++;
            }
            
             }
           i++;  
            
          }
          cout<<"\n\t**************************************\n";
          cout<<"\n\tPage Fault is:"<<count;
          getch();
          return 0;
}        
</script>

<br />
<h3 style="text-align: left;">
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Output:-</span></span></h3>
<div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXkKgSTecaNMJo4wBA9aAruAv0-zU-wIon30F1pbc4ZLkkv842PPnGRZRvE3JKS76Rx6aMESuHz0aXiRAdqzmmfx2z7xCWSxsSbSRhBVBcigOc3bIpJg7hBO7HFey2YhK3gb8DQUXAWW9_/s1600/optimal.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXkKgSTecaNMJo4wBA9aAruAv0-zU-wIon30F1pbc4ZLkkv842PPnGRZRvE3JKS76Rx6aMESuHz0aXiRAdqzmmfx2z7xCWSxsSbSRhBVBcigOc3bIpJg7hBO7HFey2YhK3gb8DQUXAWW9_/s1600/optimal.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Optimal Page Replacement</td></tr>
</tbody></table>
<span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">
</span></span></div>
<h3 style="text-align: left;">
<span class="Apple-style-span" style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">
</span></span></h3>
<div>
<h3 style="background-color: white; color: #333333; font-family: Bitter, serif, sans-serif; font-weight: normal; margin: 0px 0px 10px;">
<span style="font-size: large;"><span style="color: red; line-height: 19.1875px;">If you want to share more information about topic discussed above or find anything incorrect Please do comments.</span>  </span></h3>
</div>
<span style="font-family: Bitter, serif, sans-serif; font-size: large;"><b style="color: #333333;">For more Programs Stay Connected</b><span style="color: #333333;">..</span><a href="http://www.facebook.com/codieehome" target="_blank"><span style="color: red;">Like</span></a><span style="color: #333333;"> us on Facebook.</span></span></div>

Optimal Page Replacement Program in C++[How to]

Optimal Page Replacement Goal:- Program for Optimal page replacement Method. Method:- Replace the page that will not be used for the...

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Life Cycle of a Process [Operating System]

<div dir="ltr" style="text-align: left;" trbidi="on"><h2 style="text-align: center;"><span class="Apple-style-span" style="color: #3d85c6; font-family: 'Trebuchet MS', sans-serif;">Life Cycle of a Process</span></h2><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Goal:- </span>How a process changes its state while execution ?</span></span></h3><h3 style="text-align: left;"><span class="Apple-style-span" style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Explanation:- </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">As we know a program in execution is a process.As a process </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">executes it changes state. The state of the process is defined by the current activity of that process. Each process may be in one of the following states:- </span></span></h3><h3 style="text-align: left;"><ol style="text-align: left;"><li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">New</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">Ready</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">Running</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">Waiting</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">Terminated</span></span></li>
</ol><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">The above five states are standard states for a process in which a process remain in their life cycle.These states are found on all systems but there can be difference of naming conventions.Except of these states there are two more states which we will discuss in this post. They are</span></span></h3><h3 style="text-align: left;"><ol style="text-align: left;"><li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Suspended Ready</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Suspended Wait.</span></li>
</ol><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">Figure-1 Shows the life cycle of a Process:-</span></span></h3><div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVJGs5AWGCvvczYOg_zghIQ0baLt-Kaj1K2Zi_y2k-ogYAP8qVE2cCkyA52Ilo2yfgNDbbNWSKlMr20EjFhuYEGMlNN9kLI4M9Gso2GDKBhy9zwfmoAhn61xhzIbN4GlsodO9IhRnzF9FU/s1600/process.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="347" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVJGs5AWGCvvczYOg_zghIQ0baLt-Kaj1K2Zi_y2k-ogYAP8qVE2cCkyA52Ilo2yfgNDbbNWSKlMr20EjFhuYEGMlNN9kLI4M9Gso2GDKBhy9zwfmoAhn61xhzIbN4GlsodO9IhRnzF9FU/s1600/process.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure-1 States of a Process<br />
<br />
</td></tr>
</tbody></table><script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-size: 19px;">Now we will start with description of each state:-</span></div><div><h3><ol style="text-align: left;"><li><span class="Apple-style-span" style="color: #6aa84f; font-family: 'Trebuchet MS', sans-serif;">New:-  </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">If the process is in new state that means either the process is under creation or is being created.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="color: #6aa84f;">Ready:-</span><span class="Apple-style-span" style="font-weight: normal;"><span class="Apple-style-span" style="color: #6aa84f;"> </span>After the successful creation of a process, it is placed in Ready state by Long Term Scheduler. In this state process will wait to be assigned to a processor.In this state we can have <span class="Apple-style-span" style="color: red;">a multiple no. of processes.</span></span></span></li>
<li><span class="Apple-style-span" style="color: #6aa84f; font-family: 'Trebuchet MS', sans-serif;">Running:- </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">From the Ready state one of the process is selected and it will be scheduled or Dispatched to the Running State by Short Term Scheduler. If a process is in Running state that means instructions of the process are being executed.   ****Only <span class="Apple-style-span" style="color: red;">one process will reside in memory(Running State)</span> at any point of time.</span></span></li>
<li><span class="Apple-style-span" style="color: #6aa84f; font-family: 'Trebuchet MS', sans-serif;">Waiting:-</span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> <span class="Apple-style-span" style="font-weight: normal;">If any running process require any input/output operation the process will be moved into wait state. ** In wait state, multiple process are there. Multiple process will perform their I/O simultaneously.</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="color: #6aa84f;">Terminated:- </span><span class="Apple-style-span" style="font-weight: normal;">The Process has finished execution.</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="color: #6aa84f;">Suspended Ready:-  </span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">When the large no. of process are created and resources are short enough to manage the process then some of the process will be suspended and moved to suspended ready state. Whenever the resources are sufficient the process are resume back to the ready state by Mid term Scheduler.</span></span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="color: #6aa84f;">Suspended Wait:- </span><span class="Apple-style-span" style="font-weight: normal;"> When resources are short enough to manage the process in wait/block state  then some of the process will be suspended and moved to suspended block state. Whenever the resources are sufficient the process are resume back to the wait state by MTS. </span></span></li>
</ol><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-weight: normal;">-->**When the Process is in Suspended Ready or Suspended wait, it reside in secondary memory or Backing Store.</span></span></h3><h3 style="text-align: left;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">So this is all about Life cycle of a process and if I really helped you please let me know via comment.</span></h3></div><div><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br />
</span></div><div><h3 style="background-color: white; color: #333333; font-family: Bitter, serif, sans-serif; font-weight: normal; margin: 0px 0px 10px;"><span style="font-size: large;"><span style="color: red; line-height: 19.1875px;">If you want to share more information about topic discussed above or find anything incorrect Please do comments.</span>  </span></h3></div><span style="font-family: Bitter, serif, sans-serif; font-size: large;"><b style="color: #333333;">For more Concepts Stay Connected</b><span style="color: #333333;">..</span><a href="http://www.facebook.com/codieehome" target="_blank"><span style="color: red;">Like</span></a><span style="color: #333333;"> us on Facebook.</span></span></div>

Life Cycle of a Process [Operating System]

Life Cycle of a Process Goal:- How a process changes its state while execution ? Explanation:- As we know a program in execution is a proces...

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Program For Banker's Algorithm (Safety Sequence) in C[How to]

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><h2 style="text-align: center;"><span style="color: #3d85c6; font-family: Trebuchet MS, sans-serif;">Banker's Algorithm</span></h2><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Goal:- </span> C program For Banker's Algorithm.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Method:-  </span>Simple Rules Of Banker Algorithm.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Explanation:-  </span>Banker's Algorithm is a deadlock avoidance algorithm that checks for safe or unsafe state of a System after allocating resources to a process.</span></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">When a new process enters into system ,it must declare maximum no. of instances of each resource  that it may need.After requesting operating system run banker's algorithm to check whether after allocating requested resources,system goes into deadlock state or not. If yes then it will deny the request of resources made by process else it allocate resources to that process.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">No. of requested resources (instances of each resource) may not exceed no. of available resources in operating system and when a process completes it must release all the requested and already allocated resources.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">For implementing Banker's algorithm we should have pre-knowledge about three things:-</span></span></h3><h3 style="text-align: left;"><ul style="text-align: left;"><li><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">How many instance of each resource a process could request. (Max)</span></span></li>
<li><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">How many instance of each resource is already allocated to that process(Allocated)</span></span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">How many instance of each resource is already available(Available).</span></li>
</ul><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">We can calculate need of each process from above information:-</span></span></h3><h3 style="text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal; text-align: center;">               Need=Max - Allocated.</span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">If need<=available then request will be accepted otherwise it is denied and it will check for next process in waiting queue.(See <a href="http://codieehome.blogspot.in/2014/11/life-cycle-of-process-operating-system.html" target="_blank"><span class="Apple-style-span" style="color: red;">Life Cycle Of a Process</span></a>)</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="color: #93c47d; font-weight: normal;">Safe or Unsafe State:-</span><span style="font-weight: normal;"> A system is in Safe state if its all process finish its execution or if any process is unable to aquire its all requested resources then system will be in Unsafe state. </span></span></h3><div><script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br />
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<h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Example:-  </span>To understand banker's algorithm,we consider a system with four processes P1 through P4 and three resource type A,B and C.Resource type has 10 instances,B has 5 instances and C has total 7 instances.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Current Scenario:-</span></span></h3><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiJqWaqQHflPwyt8nDoEI0yJoxTFBcCCeF01DGuGvcm89I2mi3lrCWX37tsdK7t28I6nbUMBsxbYLe8QUOP34zr1esJsj538CB_BumG7UYy7CFf4ow0m47MFseYBCK4lbcHnFWTyVxPXNf/s1600/CropperCapture%5B1%5D.Bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="186" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiJqWaqQHflPwyt8nDoEI0yJoxTFBcCCeF01DGuGvcm89I2mi3lrCWX37tsdK7t28I6nbUMBsxbYLe8QUOP34zr1esJsj538CB_BumG7UYy7CFf4ow0m47MFseYBCK4lbcHnFWTyVxPXNf/s640/CropperCapture%5B1%5D.Bmp" width="640"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Table-1</td></tr>
</tbody></table><h3 style="text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;"><br />
</span><span style="font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Need[P2] < Available..So P2 we allocate resources to P2. After Completion of P2 ,Scenario...</span></h3><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs9rjTJ5i9enrS1FYxxenjvRbFUqUwYRsNDj3vPik_dlsWgLzdNMxvFc9o5KWjpg89tcgcotgdE4IsD2Oki1q7Jr-cQKWaffhVzDvPh7BRV5Jtud1sfVdrYknSKRb8B_fpG3NclvIpIAeU/s1600/CropperCapture%255B4%255D.Png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="152" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs9rjTJ5i9enrS1FYxxenjvRbFUqUwYRsNDj3vPik_dlsWgLzdNMxvFc9o5KWjpg89tcgcotgdE4IsD2Oki1q7Jr-cQKWaffhVzDvPh7BRV5Jtud1sfVdrYknSKRb8B_fpG3NclvIpIAeU/s640/CropperCapture%255B4%255D.Png" width="640"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Table-2</td></tr>
</tbody></table><h3 style="text-align: left;"><span style="font-weight: normal;"><span style="font-family: 'Trebuchet MS', sans-serif;">Now Need[P4] < Available so P4 will complete its execution .After that--</span></span><br />
<span style="font-weight: normal;"></span></h3><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNDsdRu-hr9U40fMJOGqkkqrTGJfhpakz9OElauh2I_zWkCGIxpvjsiaHLZOVr7RHfFtqNRC998MAtMYRPUJU8wacIt9hoBi5uI90YDtN_AdmlyGkRJsDBa69hZa0xxlJIflSFhnVO-Yuu/s1600/CropperCapture%255B1%255D.Png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="124" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNDsdRu-hr9U40fMJOGqkkqrTGJfhpakz9OElauh2I_zWkCGIxpvjsiaHLZOVr7RHfFtqNRC998MAtMYRPUJU8wacIt9hoBi5uI90YDtN_AdmlyGkRJsDBa69hZa0xxlJIflSFhnVO-Yuu/s640/CropperCapture%255B1%255D.Png" width="640"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Table-3</td></tr>
</tbody></table><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">So P1 will execute and after that P3 will take resources.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">  <span style="color: red;">Safe Sequence is :-   P2 , P4, P1,P3</span> (we can obtain one more sequence if we allocate resources to P3 before P1 .)</span></span></h3><h3 style="text-align: left;"><span style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Program:-</span></h3><span style="font-size: large;"><script class="brush: java" type="syntaxhighlighter">
#include<stdio.h>

#include<conio.h>

void main()
 {
   int process,resource,i,j,instanc,k=0,count1=0,count2=0; //count,k variables are taken for counting purpose

printf("\n\t Enter No. of Process:-\n");

printf("\t\t");

scanf("%d",&process);                            //Entering No. of Processes

printf("\n\tEnter No. of Resources:-\n");

printf("\t\t");
   scanf("%d",&resource);                       //No. of Resources

int avail[resource],max[process][resource],allot[process][resource],need[process][resource],completed[process];

for(i=0;i<process;i++)
   completed[i]=0;                             //Setting Flag for uncompleted Process

printf("\n\tEnter No. of Available Instances\n");

for(i=0;i<resource;i++)
    {
     printf("\t\t");

scanf("%d",&instanc);

avail[i]=instanc;                        // Storing Available instances
    }

printf("\n\tEnter Maximum No. of instances of resources that a Process need:\n");

for(i=0;i<process;i++)
     {
        printf("\n\t For P[%d]",i);

for(j=0;j<resource;j++)
         {
            printf("\t");

scanf("%d",&instanc);

max[i][j]=instanc;               
         } 
     }     
    printf("\n\t Enter no. of instances already allocated to process of a resource:\n");

for(i=0;i<process;i++)
     {
        printf("\n\t For P[%d]\t",i);

for(j=0;j<resource;j++)
         {
            printf("\t\t");

scanf("%d",&instanc);

allot[i][j]=instanc;

need[i][j]=max[i][j]-allot[i][j];       //calculating Need of each process
         }  
    } 
    printf("\n\t Safe Sequence is:- \t");

while(count1!=process)
    {
    count2=count1;

for(i=0;i<process;i++)
     {

for(j=0;j<resource;j++)
        {
            if(need[i][j]<=avail[j])
              {
                 k++;
              }   
            
        }     
        if(k==resource && completed[i]==0 )
         {
           printf("P[%d]\t",i);

completed[i]=1;

for(j=0;j<resource;j++)
             {
            
               avail[j]=avail[j]+allot[i][j];
           
             }  
             count1++;
             
         }
         k=0;
       } 
 
         if(count1==count2)
         {
         printf("\t\t Stop ..After this.....Deadlock \n");

break; 
       }  
 }
   getch();
}

</script></span>

<div>
<h3 style="text-align: left;">
<i style="font-weight: normal;"><span style="font-family: Trebuchet MS, sans-serif;">         </span></i></h3><h3 style="text-align: left;">
<span style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif;"><span style="font-weight: normal;">Output:</span>-</span></h3></div><div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjURU779nuuB9ZhJr_U3w1E_CyVAPcpdJUcuDv9GcLG7PoLgstBen3GTC1BkGvBhZmvPUvSkRTH39f2B7AsqlGvtOgKWilSx7UdxtUDc3KVLTHaxCaL8Xp0239aTZaaSU729MWiMW_DJGGe/s1600/banker.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="617" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjURU779nuuB9ZhJr_U3w1E_CyVAPcpdJUcuDv9GcLG7PoLgstBen3GTC1BkGvBhZmvPUvSkRTH39f2B7AsqlGvtOgKWilSx7UdxtUDc3KVLTHaxCaL8Xp0239aTZaaSU729MWiMW_DJGGe/s640/banker.png" width="640"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Banker's Algorithm</td></tr>
</tbody></table></div><div>
<span style="background-color: white; color: red; font-family: Bitter, serif, sans-serif; font-size: large; line-height: 19.1875px;">If you want to share more information about topic discussed above or find anything incorrect Please do comments.</span><span style="background-color: white; color: #333333; font-family: Bitter, serif, sans-serif; font-size: large;">  </span></div><div>
<div>
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Program For Banker's Algorithm (Safety Sequence) in C[How to]

Banker's Algorithm Goal:- C program For Banker's Algorithm. Method:- Simple Rules Of Banker Algorithm. Explanation:- Banker...

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Program For FIFO Page Replacement Method[How to]

<div dir="ltr" style="text-align: left;" trbidi="on"><h2 style="text-align: center;"><span style="background-color: white; color: #3d85c6; font-family: Trebuchet MS, sans-serif;">FIFO Page Replacement</span></h2><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Goal:- </span>Program for FIFO page replacement Method.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Method:- </span>First in First out (Queue)</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">Explanation:- </span>This is the simplest page replacement algorithm.In a page replacement algorithm we decide when a page replacement occures then which frames are to be replaced.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">For evaluating an algorithm we take a particular string of memory references ,called<span style="color: red;"> reference string</span>.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">In FIFO page replacement algorithm- for each page we track the time when it was brought into the memory and when any replacement request comes then oldest page is chosen. </span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">If we choose a queue to hold all pages in memory then its more easy to understand and implement rather than tracking time of all pages.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">If we are using a queue in our implementation then :</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">                 1.Replacement of any page takes place at the head of the  queue and</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">                 2.Insertion of pages takes place at the tail of the queue.</span></span></h3><div><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">FIFO is easy to understand but there is no practical use of this algorithm in now-a-days because performance of FIFO is not always good.</span></span></h3></div><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="color: red; font-weight: normal;">Page Fault:- </span><span style="font-weight: normal;"> Page Fault is a interrput that occurs when a program request page that is not in real memory.Then this interrput sends signal to OS to fetch that page from Virtual memory and load it into RAM.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">**Program explained here counts the no. of page fault occurs  when a input reference string is implemented onto Memory according to FIFO replacement method.</span></span></h3><h3 style="text-align: left;"><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Example:-</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;"><span style="color: #93c47d;">               </span>Reference string- 7,0,1,2,0,3,0,4</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">                 No. of frames: 3</span></span></h3><h3><table align="center" border="1" cellpadding="10"><tbody>
<tr>   <th rowspan="2"><h3><span style="font-family: Trebuchet MS, sans-serif;">Frame NO.</span></h3></th>   <th colspan="9"><h3><span style="font-family: Trebuchet MS, sans-serif;">Reference String(Page Values)</span></h3></th> </tr>
<tr>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">Initially</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">7</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">1</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">2</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">3</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">0</span></h3></th>   <th><h3><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;">4</span></h3></th> </tr>
<tr>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">7</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">7</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">7</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">2</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">2</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">2</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">2</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">4</span></h3></td> </tr>
<tr>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">2</span></h3></td>    <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">0</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">0</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">0</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">0</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">3</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">3</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">3</span></h3></td> </tr>
<tr>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">3</span></h3></td>    <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">-1</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">1</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">1</span></h3></td>   <td><h3><span style="color: red; font-family: Trebuchet MS, sans-serif;">0</span></h3></td>   <td><h3><span style="font-family: Trebuchet MS, sans-serif;">0</span></h3></td> </tr>
</tbody></table></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">When any page value already presented in frames then no page fault will occur.</span></span></h3><h3 style="text-align: left;"><span style="font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Number of Page Fault occured with above string is 7 and shown in table and colored red.</span></span></h3><h3 style="text-align: left;"><span style="color: #93c47d; font-family: Trebuchet MS, sans-serif;"><span style="font-weight: normal;">Program:-</span></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>#include<stdio.h></i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>#include<conio.h></i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i> int main()</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>   {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      int a[10],count=0,i,j,k,n,m;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     </i></span><i style="font-family: 'Trebuchet MS', sans-serif;"> printf("\n\tEnter No. of Pages:\n");</i></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      printf("\t");</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      scanf("%d",&n);</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      printf("\n\tEnter values of Reference String :\n");</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      for(i=0;i<n;i++)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>       printf("\t");              </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>       scanf("%d",&a[i]);</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>       }</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     printf("\n\tEnter no. of frames:\n");</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      printf("\t");</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     scanf("%d",&m);</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     }</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     int count1[m];</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     for(i=0;i<m;i++)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>       count1[i]=-1;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     printf("\n Displaying Distribution-----------\n");</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>     for(i=0;i<n;i++)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>            k=0;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>            for(j=0;j<m;j++)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                if(a[i]==count1[j])</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                  {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                     k++;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                     count--;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                  }   </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             }     </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             count++;</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             if(count<=m && k==0)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                   count1[i]=a[i];</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                }   </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             else if(k==0)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                  {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                      count1[(count-1)%m]=a[i];</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>                  }</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>              printf("\n\t********************************\n"); </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             for(j=0;j<m;j++)</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>             {</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>              printf("\t");       </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>              printf("(%d)\t",count1[j]);</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>              }</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      } </i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      printf("\n\n\tTotal Page Faults %d",count);</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      getch();</i></span></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>      return 0;</i></span></h3><h3><i><span style="font-family: Trebuchet MS, sans-serif;"></span></i></h3><h3><span style="font-family: Trebuchet MS, sans-serif;"><i>}          </i></span></h3><h3 style="text-align: left;"><span style="color: #93c47d; font-family: 'Trebuchet MS', sans-serif; font-weight: normal;">Output:-</span></h3><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7FJdDSvfAX-srGt5CbydGAxRNdmD5BAgTozQIGZe7nC2tWr85PkBH6m9s_Laza1j0CSzNzE93rlcOiUYrPVQIsL40o3cLVMWb3QS0xUM3uFbsV-ptygXiplLF-zfLyBHCBMfTZS5n8V7R/s1600/pf.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="504" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7FJdDSvfAX-srGt5CbydGAxRNdmD5BAgTozQIGZe7nC2tWr85PkBH6m9s_Laza1j0CSzNzE93rlcOiUYrPVQIsL40o3cLVMWb3QS0xUM3uFbsV-ptygXiplLF-zfLyBHCBMfTZS5n8V7R/s640/pf.png" width="640" /></a></div><div><br />
<br />
</div><div><h3 style="background-color: white; color: #333333; font-family: Bitter, serif, sans-serif; font-weight: normal; margin: 0px 0px 10px;"><span style="font-size: large;"><span style="color: red; line-height: 19.1875px;">If you want to share more information about topic discussed above or find anything incorrect Please do comments.</span>  </span></h3></div></div>

Program For FIFO Page Replacement Method[How to]

FIFO Page Replacement Goal:- Program for FIFO page replacement Method. Method:- First in First out (Queue) Explanation:- This is the simples...

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