Priority Cpu Scheduling Program In Java Code Example

Example: preemptive priority scheduling implementation in c

#include <iostream> #include <algorithm>  #include <iomanip> #include <string.h>  using namespace std;  struct process {     int pid;     int arrival_time;     int burst_time;     int priority;     int start_time;     int completion_time;     int turnaround_time;     int waiting_time;     int response_time; };  int main() {      int n;     struct process p[100];     float avg_turnaround_time;     float avg_waiting_time;     float avg_response_time;     float cpu_utilisation;     int total_turnaround_time = 0;     int total_waiting_time = 0;     int total_response_time = 0;     int total_idle_time = 0;     float throughput;     int burst_remaining[100];     int is_completed[100];     memset(is_completed,0,sizeof(is_completed));      cout << setprecision(2) << fixed;      cout<<"Enter the number of processes: ";     cin>>n;      for(int i = 0; i < n; i++) {         cout<<"Enter arrival time of process "<<i+1<<": ";         cin>>p[i].arrival_time;         cout<<"Enter burst time of process "<<i+1<<": ";         cin>>p[i].burst_time;         cout<<"Enter priority of the process "<<i+1<<": ";         cin>>p[i].priority;         p[i].pid = i+1;         burst_remaining[i] = p[i].burst_time;         cout<<endl;     }      int current_time = 0;     int completed = 0;     int prev = 0;      while(completed != n) {         int idx = -1;         int mx = -1;         for(int i = 0; i < n; i++) {             if(p[i].arrival_time <= current_time && is_completed[i] == 0) {                 if(p[i].priority > mx) {                     mx = p[i].priority;                     idx = i;                 }                 if(p[i].priority == mx) {                     if(p[i].arrival_time < p[idx].arrival_time) {                         mx = p[i].priority;                         idx = i;                     }                 }             }         }          if(idx != -1) {             if(burst_remaining[idx] == p[idx].burst_time) {                 p[idx].start_time = current_time;                 total_idle_time += p[idx].start_time - prev;             }             burst_remaining[idx] -= 1;             current_time++;             prev = current_time;                          if(burst_remaining[idx] == 0) {                 p[idx].completion_time = current_time;                 p[idx].turnaround_time = p[idx].completion_time - p[idx].arrival_time;                 p[idx].waiting_time = p[idx].turnaround_time - p[idx].burst_time;                 p[idx].response_time = p[idx].start_time - p[idx].arrival_time;                  total_turnaround_time += p[idx].turnaround_time;                 total_waiting_time += p[idx].waiting_time;                 total_response_time += p[idx].response_time;                  is_completed[idx] = 1;                 completed++;             }         }         else {              current_time++;         }       }      int min_arrival_time = 10000000;     int max_completion_time = -1;     for(int i = 0; i < n; i++) {         min_arrival_time = min(min_arrival_time,p[i].arrival_time);         max_completion_time = max(max_completion_time,p[i].completion_time);     }      avg_turnaround_time = (float) total_turnaround_time / n;     avg_waiting_time = (float) total_waiting_time / n;     avg_response_time = (float) total_response_time / n;     cpu_utilisation = ((max_completion_time - total_idle_time) / (float) max_completion_time )*100;     throughput = float(n) / (max_completion_time - min_arrival_time);      cout<<endl<<endl;      cout<<"#P\t"<<"AT\t"<<"BT\t"<<"PRI\t"<<"ST\t"<<"CT\t"<<"TAT\t"<<"WT\t"<<"RT\t"<<"\n"<<endl;      for(int i = 0; i < n; i++) {         cout<<p[i].pid<<"\t"<<p[i].arrival_time<<"\t"<<p[i].burst_time<<"\t"<<p[i].priority<<"\t"<<p[i].start_time<<"\t"<<p[i].completion_time<<"\t"<<p[i].turnaround_time<<"\t"<<p[i].waiting_time<<"\t"<<p[i].response_time<<"\t"<<"\n"<<endl;     }     cout<<"Average Turnaround Time = "<<avg_turnaround_time<<endl;     cout<<"Average Waiting Time = "<<avg_waiting_time<<endl;     cout<<"Average Response Time = "<<avg_response_time<<endl;     cout<<"CPU Utilization = "<<cpu_utilisation<<"%"<<endl;     cout<<"Throughput = "<<throughput<<" process/unit time"<<endl;   }  /*  AT - Arrival Time of the process BT - Burst time of the process ST - Start time of the process CT - Completion time of the process TAT - Turnaround time of the process WT - Waiting time of the process RT - Response time of the process  Formulas used:  TAT = CT - AT WT = TAT - BT RT = ST - AT  */  }