Introduction to FCFS disk scheduling :
The simplest form of disk scheduling is, of course, the first-come, first-served (FCFS) algorithm. This algorithm is intrinsically fair, but it generally does not provide the fastest service. Consider, for example, a disk queue with requests for I/O to blocks on cylinders 98, 183, 37, 122, 14, 124, 65, 67. If the disk head is initially at cylinder 53, it will first move from 53 to 98, then to 183, 37, 122, 14, 124, 65, and finally to 67, for a total head movement of 640 cylinders.
C program for FCFS disk scheduling :
OUTPUT :
The simplest form of disk scheduling is, of course, the first-come, first-served (FCFS) algorithm. This algorithm is intrinsically fair, but it generally does not provide the fastest service. Consider, for example, a disk queue with requests for I/O to blocks on cylinders 98, 183, 37, 122, 14, 124, 65, 67. If the disk head is initially at cylinder 53, it will first move from 53 to 98, then to 183, 37, 122, 14, 124, 65, and finally to 67, for a total head movement of 640 cylinders.
C program for FCFS disk scheduling :
#include<stdio.h>
int main()
{
int
queue[20],n,head,i,j,k,seek=0,max,diff;
float avg;
printf("Enter the max range of
disk\n");
scanf("%d",&max);
printf("Enter the size of queue
request\n");
scanf("%d",&n);
printf("Enter the queue of disk
positions to be read\n");
for(i=1;i<=n;i++)
scanf("%d",&queue[i]);
printf("Enter the initial head
position\n");
scanf("%d",&head);
queue[0]=head;
for(j=0;j<=n-1;j++)
{
diff=abs(queue[j+1]-queue[j]);
seek+=diff;
printf("Disk head
moves from %d to %d with seek %d\n",queue[j],queue[j+1],diff);
}
printf("Total seek time is
%d\n",seek);
avg=seek/(float)n;
printf("Average seek time is
%f\n",avg);
return 0;
}
OUTPUT :
This comment has been removed by the author.
ReplyDeletewhere did u use the max variable?
ReplyDeletemax no of cylinders in disk
Deletewhat is the use of the abs shows declaration function please give me a solution
Deleteabs means modulus...makes a negative number positive
ReplyDeleteNice Web site for Educaion https://www.wisdommaterials.com
ReplyDelete