Department of Computer Science and Engineering
Lab Report
Course Title: Operating System Lab
Course Code: CSE-3632
Submitted by:
Name: Mahiah Kulsum
ID: C213260
Sec: 6BF
Submitted to:
Shefayatuj Johara Chowdhury
Lecturer
Date: 26/06/24
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First Come First Search (FCFS) Algorithm, Assignments of Operating Systems
The implementation of the first come first search (fcfs) algorithm in c++. Fcfs is a scheduling algorithm in which processes are executed in the order of their arrival, with the first process that arrives being the first one to be executed. The code for the fcfs algorithm, which takes in the number of processes, their burst times, and arrival times, and then calculates the waiting time, turnaround time, and average waiting and turnaround times for each process. The document also includes a section for generating a gantt chart to visualize the scheduling of the processes. This document could be useful for students studying operating systems, computer architecture, or algorithms, as it provides a practical implementation of a fundamental scheduling algorithm.
Typology: Assignments
2023/2024
1 / 19
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Department of Computer Science and Engineering
Lab Report
Course Title: Operating System Lab
Course Code: CSE- 3632
Submitted by:
Name: Mahiah Kulsum
ID: C
Sec: 6BF
Submitted to:
Shefayatuj Johara Chowdhury
Lecturer
Date : 26/06/
1. First Come First Search(FCFS)
include
include
using namespace std;
define s 100
struct Process { int id; int burstTime; int arrivalTime; }; bool compareArrivalTime ( const Process& a, const Process& b) { return a.arrivalTime < b.arrivalTime; } int main () { int n, wt[s], tat[s], avwt = 0 , avtat = 0 ; cout << "Total number of processes" << endl; cin >> n; Process processes[s]; cout << "Enter Process Burst Time and Arrival Time" << endl; for ( int i = 0 ; i < n; i++) { cout << "P[" << i + 1 << "]:"; processes[i].id = i + 1 ; cin >> processes[i].burstTime >> processes[i].arrivalTime; } // Sort processes based on arrival time sort(processes, processes + n, compareArrivalTime); wt[ 0 ] = 0 ; for ( int i = 1 ; i < n; i++) { wt[i] = processes[i - 1 ].burstTime + wt[i - 1 ]; } cout << "\nProcess\t\tBurst Time\tArrival Time\tWaiting Time\tTurnaround Time"; for ( int i = 0 ; i < n; i++) { tat[i] = processes[i].burstTime + wt[i]; avwt += wt[i]; avtat += tat[i]; cout << "\nP[" << processes[i].id << "]\t\t" << processes[i].burstTime << "\t\t" << processes[i].arrivalTime << "\t\t" << wt[i] << "\t\t" << tat[i]; }
2. Shortest Job First(SJF)
include
using namespace std; int main () { int p, i, j, sum = 0 , min, index; float awt = 0 , atat = 0 ; cout << "\nEnter number of process: "; cin >> p; int proc[p]; int *bt = new int [p]; int *wt = new int [p]; int *gc = new int [p]; int *tat = new int [p]; int *tmp = new int [p]; cout << "\nEnter Burst time:\n"; for (i = 0 ; i < p; i++) { cin >> bt[i]; tmp[i] = bt[i]; } sort(bt, bt + p); cout << "\n========================================================\n"; cout << "\t\tGantt Chart"; cout << "\n========================================================\n"; for (j = 0 ; j <= p; j++) { min = 100 ; for (i = 0 ; i < p; i++) { if (min > tmp[i] && tmp[i] != - 1 ) { min = tmp[i]; index = i;
gc[j] = sum; wt[j] = sum; sum += tmp[index]; tat[j] = sum; tmp[index] = - 1 ; //indicate process executed if (j == p) break ; cout << 'P' << index + 1 << " | "; proc[j] = index + 1 ; } cout << "\n------------------------------------------------------ --\n"; sum = 0 ; for (j = 0 ; j <= p; j++) { if (gc[j] < 10 ) cout << 0 ; cout << gc[j] << " "; sum += gc[j]; } cout << endl; atat = (sum *1.0) / p; cout << "\n------------------------------------------------------ --"; cout << "\nProcess\t\tCBT\tWaiting Time\tTurn Around Time"; cout << "\n------------------------------------------------------ --\n"; for (i = 0 ; i < p; i++) { cout << "P[" << proc[i] << "]\t\t" << bt[i] << "\t" << wt[i] << "\t\t" << tat[i] << endl; awt = awt + wt[i]; } awt = (awt *1.0) / p; cout << "\n\nTotal Waiting Time: " << awt;
cout << "Enter the time quantum: "; cin >> t; for (i = 0 ; i < n; i++) { b[i] = bur[i] / t; if ((bur[i] % t) != 0 ) b[i] += 1 ; m += b[i]; } cout << "\n\t\tRound Robin Scheduling\n"; cout << "\nGantt Chart\n"; for (i = 0 ; i < m; i++) cout << "--------"; cout << "\n"; a[ 0 ] = 0 ; while (j < m) { if (x == n - 1 ) x = 0 ; else x++; if (bur[x] >= t) { bur[x] - = t; a[j + 1 ] = a[j] + t; if (b[x] == 1 ) { p[s] = x; k[s] = a[j + 1 ]; s++; } j++; b[x] - = 1 ; cout << " P" << (x + 1 ) << " |"; } else if (bur[x] != 0 ) { a[j + 1 ] = a[j] + bur[x]; bur[x] = 0 ; if (b[x] == 1 ) { p[s] = x; k[s] = a[j + 1 ]; s++; }
j++; b[x] - = 1 ; cout << " P" << (x + 1 ) << " |"; } } cout << "\n"; for (i = 0 ; i < m; i++) cout << "--------"; cout << "\n"; for (j = 0 ; j <= m; j++) cout << a[j] << "\t"; for (i = 0 ; i < n; i++) { for (j = i + 1 ; j < n; j++) { //ascending order if (p[i] > p[j]) { temp = p[i]; p[i] = p[j]; p[j] = temp; temp = k[i]; k[i] = k[j]; k[j] = temp; } } } for (i = 0 ; i < n; i++) { wat[i] = k[i] - bur1[i]; tur[i] = k[i]; } for (i = 0 ; i < n; i++) { ttur += tur[i]; twat += wat[i]; } cout << "\n\n"; for (i = 0 ; i < 30 ; i++) cout << "-"; cout << "\nProcess\tBurst\tTrnd\tWait\n"; for (i = 0 ; i < 30 ; i++) cout << "-"; for (i = 0 ; i < n; i++)
4. Banker's Algorithm
include
using namespace std; int main () { int p,r,i,j,k; cout<<"Enter the number of processes: "; cin>>p; cout<<"Enter the number of resources: "; cin>>r; int alloc[p][r],max[p][r],avail[r]; cout<<"Enter the allocation matrix:"<>alloc[i][j]; } } cout<<"Enter the maximum matrix:"<>max[i][j]; } } cout<<"Enter the available resources:"<>avail[i]; } int finish[p],safe[p],a= 0 ; for (k= 0 ;k for (k= 0 ;k avail[j]) { f = 1 ; break ; } } if (f== 0 ) { safe[a++]=i; for (y= 0 ;y"; cout<< " P" < h++; pageFaults--; } } pageFaults++; //miss hole if((pageFaults <= frames) && (h == 0 )) { temp[m] = incomingStream[m]; } else if(h == 0 ) { temp[(pageFaults - 1 ) % frames] = incomingStream[m];// Replace the oldest page } cout << "\n"; cout << incomingStream[m] << "\t\t\t"; for(n = 0 ; n < frames; n++) { if(temp[n] != - 1 ) cout << temp[n] << "\t\t\t"; else cout << "- \t\t\t"; } } cout << "\n\nPage Faults:\t" << pageFaults; cout << "\nHits :\t" << pages - pageFaults; return 0 ; }
Output:
6. Least Recently Used (LRU) Page Replacement
include
using namespace std; int main () { int incomingStream[ 100 ]; int numPages, frames,h; cout<<"Enter the number of pages: "; cin>>numPages; cout<<"Enter the page references: "; for ( int i = 0 ; i < numPages; ++i) { cin>>incomingStream[i]; } cout<<"Enter the number of frames: "; cin>>frames; int pageFaults = 0 ; int hitCount = 0 ; int m, n, s, pages; pages = numPages; cout<<"Incoming"; for ( int i = 0 ; i < frames; ++i) { cout<<"Frame "<
Output:
7. Optimal Page Replacement(OPR)
include
using namespace std; int search(int key, int frame_items[], int frame_occupied) { for (int i = 0 ; i < frame_occupied; i++) if (frame_items[i] == key) return 1 ; return 0 ; } void printOuterStructure(int max_frames){ printf("Ref str "); for(int i = 0 ; i < max_frames; i++) printf("Frame%d ", i+ 1 ); }
void printCurrFrames(int item, int frame_items[], int frame_occupied, int max_frames){ cout << "\n" << item << "\t\t"; for(int i = 0 ; i < max_frames; i++){ if (i < frame_occupied) cout << frame_items[i] << "\t\t"; else cout << "- \t\t"; } } int predict(int ref_str[], int frame_items[], int refStrLen, int index, int frame_occupied) { int result = - 1 , farthest = index; for (int i = 0 ; i < frame_occupied; i++) { int j; for (j = index; j < refStrLen; j++) { if (frame_items[i] == ref_str[j]) { if (j > farthest) { farthest = j; result = i; } break; } } if (j == refStrLen) return i; } return (result == - 1 )? 0 : result; } void optimalPage(int ref_str[], int refStrLen, int frame_items[], int max_frames) { int frame_occupied = 0 ; printOuterStructure(max_frames);