C++ Program For PRIORITY WITH NON - PREEMPTIVE Scheduling Algorithm || dot clu

C++ Program For PRIORITY WITH  NON - PREEMPTIVE Scheduling Algorithm

It is important to distinguish preemptive from non-preemptive schedulingalgorithms. Preemption means the operating system moves a process from running to ready without the process requesting it. Without preemption, the system implements ``run to completion (or yield or block)''.

Non-Preemptive Scheduling

Non-Preemptive Scheduling means once a process starts its execution or the CPU is processing a specific process it cannot be halted or in other words we cannot preempt (take control) the CPU to some other process.

A computer system implementing this cannot support the execution of process in a multi task fashion. It executes all the processes in a sequential manner.

It is not practical as all processes are not of same priority and are not always known to the system in advance.

Source Code:

1. #include <iostream>
2. using namespace std;
3. 
   
4. int main()
5. {   
6.  int n;
7.     cout<<"enter your toal no. of process ";
8.     cin>>n;
9.     float total,wait[n];
10.     float p[n],twaiting=0,waiting=0;
11.     int proc;
12.     int stack[n];
13.     float brust[n],arrival[n],sbrust,temp[n],top=n,prority[n];
14.     int i;
15.     for(i=0;i<n;i++)
16.     {
17.         p[i]=i;
18.         stack[i]=i;
19.         cout<<"\nenter arival time "<<i+1<<": ";
20.         cin>>arrival[i];
21.         cout<<"enter brust time "<<i+1<<": ";
22.         cin>>brust[i];
23.         cout<<"enter prority time "<<i+1<<": ";
24.         cin>>prority[i];
25.         cout<<"\n";      
26.         temp[i]=arrival[i];
27.         sbrust=brust[i]+sbrust;              
28.     }
29.     for(i=0;i<sbrust;i++)
30.     {    
31.         //section 1
32.         proc=stack[0];
33.         if(temp[proc]==i)
34.         {
35.           
36.             twaiting=0;
37.         }
38.         else
39.         {    
40.             twaiting=i-(temp[proc]);
41.          }
42.            temp[proc]=i+1;    
43.            wait[proc]=wait[proc]+twaiting;
44.             waiting=waiting+(twaiting);
45.             brust[proc]=brust[proc]-1;
46.                            
47.         if(brust[proc]==0)
48.         {
49.             for(int x=0;x<top-1;x++)
50.             {
51.                 stack[x]=stack[x+1];   
52.             }
53.             top=top-1;       
54.         for(int z=0;z<top-1;z++)
55.         {   
56.             if((prority[stack[0]]>prority[stack[z+1]]) && (arrival[stack[z+1]] <= i+1))
57.             {
58.                    int t=stack[0];
59.             stack[0]=stack[z+1];
60.             stack[z+1]=t;
61.             }
62.                 }
63.         }  
64.     }
65. cout<<"\nAverage waiting time is: "<<waiting/n;
66. float tu=(sbrust+waiting)/n;
67. cout<<endl<<"Average turnaround time is: "<<tu;
68. return 0;
69. }