Multi-level queue scheduling algorithm

EXPERIMENT

OBJECTIVE

*Write a C program to simulate multi-level queue scheduling algorithm considering the following scenario. All

the processes in the system are divided into two categories – system processes and user processes. System

processes are to be given higher priority than user processes. The priority of each process ranges from 1 to 3.

Use fixed priority scheduling for all the processes.

DESCRIPTION

Multi-level queue scheduling algorithm is used in scenarios where the processes can be classified into groups

based on property like process type, CPU time, IO access, memory size, etc. In a multi-level queue scheduling

algorithm, there will be 'n' number of queues, where 'n' is the number of groups the processes are classified

into. Each queue will be assigned a priority and will have its own scheduling algorithm like round-robin

scheduling or FCFS. For the process in a queue to execute, all the queues of priority higher than it should be

empty, meaning the process in those high priority queues should have completed its execution. In this

scheduling algorithm, once assigned to a queue, the process will not move to any other queues.

coding

main()

{

int p[20],bt[20], su[20], wt[20],tat[20],i, k, n, temp;

float wtavg, tatavg;

clrscr();

printf("Enter the number of processes --- ");

scanf("%d",&n);

for(i=0;i<n;i++)

{

p[i] = i;

printf("Enter the Burst Time of Process %d --- ", i);

scanf("%d",&bt[i]);

printf("System/User Process (0/1) ? --- ");

scanf("%d", &su[i]);

}

for(i=0;i<n;i++)

for(k=i+1;k<n;k++)

if(su[i] > su[k])

{

temp=p[i];

p[i]=p[k];

p[k]=temp;

temp=bt[i];

bt[i]=bt[k];

bt[k]=temp;

temp=su[i];

su[i]=su[k];

su[k]=temp;

}

wtavg = wt[0] = 0;

tatavg = tat[0] = bt[0];

for(i=1;i<n;i++)

{

wt[i] = wt[i-1] + bt[i-1];

tat[i] = tat[i-1] + bt[i];

wtavg = wtavg + wt[i];

tatavg = tatavg + tat[i];

}

printf("\nPROCESS\t\t SYSTEM/USER PROCESS \tBURST TIME\tWAITING TIME\tTURNAROUND TIME");

for(i=0;i<n;i++)

printf("\n%d \t\t %d \t\t %d \t\t %d \t\t %d ",p[i],su[i],bt[i],wt[i],tat[i]);

printf("\nAverage Waiting Time is --- %f",wtavg/n);

printf("\nAverage Turnaround Time is --- %f",tatavg/n);

getch();

}