Sunday, March 11, 2012

IMPLEMENTATION OF DISK SCHEDULING ALGORITHMS


Ex. No. :11

IMPLEMENTATION OF DISK SCHEDULING ALGORITHMS


AIM:
            To write a ‘C’ program to implement the Disk Scheduling algorithm for First Come First Served (FCFS), Shortest Seek Time First (SSTF), and SCAN.

PROBLEM DESCRIPTION:
              Disk Scheduling is the process of deciding which of the cylinder request is in the ready queue is to be accessed next.
              The access time and the bandwidth can be improved by scheduling the servicing of disk I/O requests in good order.
Access Time:
               The access time has two major components:  Seek time and Rotational Latency.           
Seek Time:
               Seek time is the time for disk arm to move the heads to the cylinder containing the desired sector.
Rotational Latency:
              Rotational latency is the additional time waiting for the disk to rotate the desired sector to the disk head.
Bandwidth:
              The disk bandwidth is the total number of bytes transferred, divided by the total time between the first request for service and the completion of the last transfer.
ALGORITHM:
  1. Input the maximum number of cylinders and work queue and its head starting position.
  2.  First Come First Serve Scheduling (FCFS) algorithm – The operations are performed in order requested.
  3.  There is no reordering of work queue.
  4. Every request is serviced, so there is no starvation.
  5. The seek time is calculated.
  6. Shortest Seek Time First Scheduling (SSTF) algorithm – This algorithm selects the request with the minimum seek time from the current head position.
  7. Since seek time increases with the number of cylinders traversed by the head, SSTF chooses the pending request closest to the current head position.
  8. The seek time is calculated.
  9. SCAN Scheduling algorithm – The disk arm starts at one end of the disk, and moves toward the other end, servicing requests as it reaches each cylinder, until it gets to the other end of the disk.
  10. At the other end, the direction of head movement is reversed, and servicing continues.
  11. The head continuously scans back and forth across the disk.
  12. The seek time is calculated.
  13. Display the seek time and terminate the program

Program :

#include<stdio.h>
#include<math.h>

void fcfs(int noq, int qu[10], int st)
{
 int i,s=0;
 for(i=0;i<noq;i++)
 {
  s=s+abs(st-qu[i]);
  st=qu[i];
  }
 printf("\n Total seek time :%d",s);
}

void sstf(int noq, int qu[10], int st, int visit[10])
{
 int min,s=0,p,i;
 while(1)
{
  min=999;
  for(i=0;i<noq;i++)
   if (visit[i] == 0)
    {
      if(min > abs(st - qu[i]))
       {
        min = abs(st-qu[i]);
        p = i;
        }
      }
 if(min == 999)
  break;
  visit[p]=1;
  s=s + min;
  st = qu[p];
  }
 printf("\n Total seek time is: %d",s);
 }

void scan(int noq, int qu[10], int st, int ch)
{
 int i,j,s=0;
 for(i=0;i<noq;i++)
 {
  if(st < qu[i])
  {
   for(j=i-1; j>= 0;j--)
   {
    s=s+abs(st - qu[j]);
    st = qu[j];
    }
   if(ch == 3)
   {
   s = s + abs(st - 0);
   st = 0;
   }
  for(j = 1;j < noq;j++)
  {
   s= s + abs(st - qu[j]);
   st = qu[j];
   }
  break;
 }
}
printf("\n Total seek time : %d",s);
}

int main()
{
 int n,qu[20],st,i,j,t,noq,ch,visit[20];
 printf("\n Enter the maximum number of cylinders : ");
 scanf("%d",&n);
 printf("enter number of queue elements");
 scanf("%d",&noq);
 printf("\n Enter the work queue");
 for(i=0;i<noq;i++)
 {
  scanf("%d",&qu[i]);
  visit[i] = 0;
  }
 printf("\n Enter the disk head starting posision: \n");
 scanf("%d",&st);
 while(1)
 {
  printf("\n\n\t\t MENU \n");
  printf("\n\n\t\t 1. FCFS \n");
  printf("\n\n\t\t 2. SSTF \n");
  printf("\n\n\t\t 3. SCAN \n");
  printf("\n\n\t\t 4. EXIT \n");
  printf("\nEnter your choice: ");
  scanf("%d",&ch);
  if(ch > 2)
   {
   for(i=0;i<noq;i++)
   for(j=i+1;j<noq;j++)
   if(qu[i]>qu[j])
   {
    t=qu[i];
    qu[i] = qu[j];
    qu[j] = t;
    }
   }
   switch(ch)
    {
    case 1: printf("\n FCFS \n");
            printf("\n*****\n");
            fcfs(noq,qu,st);
            break;

    case 2: printf("\n SSTF \n");
            printf("\n*****\n");
            sstf(noq,qu,st,visit);
            break;
    case 3: printf("\n SCAN \n");
            printf("\n*****\n");
            scan(noq,qu,st,ch);
            break;
    case 4: exit(0);
 }
 }
}

Output

"disksche.c" 122L, 2076C written
[anandh@localhost ~]$ cc disksche.c
[anandh@localhost ~]$ ./a.out

 Enter the maximum number of cylinders : 200
enter number of queue elements5

 Enter the work queue23
89
132
42
187

 Enter the disk head starting posision:
100
                



                  MENU

                 1. FCFS

                 2. SSTF

                 3. SCAN

                 4. EXIT

Enter your choice: 1

 FCFS

*****

 Total seek time : 421

                 MENU

                 1. FCFS

                 2. SSTF

                 3. SCAN

                 4. EXIT

Enter your choice: 2

 SSTF

*****

 Total seek time is: 273

                 MENU

                 1. FCFS

                 2. SSTF

                 3. SCAN

                 4. EXIT

Enter your choice: 3

 SCAN

*****

 Total seek time : 287

                 MENU

                 1. FCFS

                 2. SSTF

                 3. SCAN

                 4. EXIT

Enter your choice: 4



 Result:
                       Thus the C program to implement the Disk scheduling algorithms namely FCFS, SSTF,
  and SCAN algorithms was written and executed. The obtained outputs were verified.   

24 comments:

  1. very helpfull.....tanx a lot.........

    ReplyDelete
    Replies
    1. Engineer Portal - Prem Sasi Kumar Arivukalanjiam: Implementation Of Disk Scheduling Algorithms >>>>> Download Now

      >>>>> Download Full

      Engineer Portal - Prem Sasi Kumar Arivukalanjiam: Implementation Of Disk Scheduling Algorithms >>>>> Download LINK

      >>>>> Download Now

      Engineer Portal - Prem Sasi Kumar Arivukalanjiam: Implementation Of Disk Scheduling Algorithms >>>>> Download Full

      >>>>> Download LINK O0

      Delete
  2. how do the prog set up for a disk request file...?

    ReplyDelete
  3. thank u for the prog..

    ReplyDelete
  4. Thank you so much , Sir !!!!!

    ReplyDelete
  5. Can v write the same algorithm using linked list implementation in c? How

    ReplyDelete
    Replies
    1. Yes using doubly linked list we can!

      Delete

Slider

Image Slider By engineerportal.blogspot.in The slide is a linking image  Welcome to Engineer Portal... #htmlcaption

Tamil Short Film Laptaap

Tamil Short Film Laptaap
Laptapp

Labels

About Blogging (1) Advance Data Structure (2) ADVANCED COMPUTER ARCHITECTURE (4) Advanced Database (4) ADVANCED DATABASE TECHNOLOGY (4) ADVANCED JAVA PROGRAMMING (1) ADVANCED OPERATING SYSTEMS (3) ADVANCED OPERATING SYSTEMS LAB (2) Agriculture and Technology (1) Analag and Digital Communication (1) Android (1) Applet (1) ARTIFICIAL INTELLIGENCE (3) aspiration 2020 (3) assignment cse (12) AT (1) AT - key (1) Attacker World (6) Basic Electrical Engineering (1) C (1) C Aptitude (20) C Program (87) C# AND .NET FRAMEWORK (11) C++ (1) Calculator (1) Chemistry (1) Cloud Computing Lab (1) Compiler Design (8) Computer Graphics Lab (31) COMPUTER GRAPHICS LABORATORY (1) COMPUTER GRAPHICS Theory (1) COMPUTER NETWORKS (3) computer organisation and architecture (1) Course Plan (2) Cricket (1) cryptography and network security (3) CS 810 (2) cse syllabus (29) Cyberoam (1) Data Mining Techniques (5) Data structures (3) DATA WAREHOUSING AND DATA MINING (4) DATABASE MANAGEMENT SYSTEMS (8) DBMS Lab (11) Design and Analysis Algorithm CS 41 (1) Design and Management of Computer Networks (2) Development in Transportation (1) Digital Principles and System Design (1) Digital Signal Processing (15) DISCRETE MATHEMATICS (1) dos box (1) Download (1) ebooks (11) electronic circuits and electron devices (1) Embedded Software Development (4) Embedded systems lab (4) Embedded systems theory (1) Engineer Portal (1) ENGINEERING ECONOMICS AND FINANCIAL ACCOUNTING (5) ENGINEERING PHYSICS (1) english lab (7) Entertainment (1) Facebook (2) fact (31) FUNDAMENTALS OF COMPUTING AND PROGRAMMING (3) Gate (3) General (3) gitlab (1) Global warming (1) GRAPH THEORY (1) Grid Computing (11) hacking (4) HIGH SPEED NETWORKS (1) Horizon (1) III year (1) INFORMATION SECURITY (1) Installation (1) INTELLECTUAL PROPERTY RIGHTS (IPR) (1) Internal Test (13) internet programming lab (20) IPL (1) Java (38) java lab (1) Java Programs (28) jdbc (1) jsp (1) KNOWLEDGE MANAGEMENT (1) lab syllabus (4) MATHEMATICS (3) Mechanical Engineering (1) Microprocessor and Microcontroller (1) Microprocessor and Microcontroller lab (11) migration (1) Mini Projects (1) MOBILE AND PERVASIVE COMPUTING (15) MOBILE COMPUTING (1) Multicore Architecute (1) MULTICORE PROGRAMMING (2) Multiprocessor Programming (2) NANOTECHNOLOGY (1) NATURAL LANGUAGE PROCESSING (1) NETWORK PROGRAMMING AND MANAGEMENT (1) NETWORKPROGNMGMNT (1) networks lab (16) News (14) Nova (1) NUMERICAL METHODS (2) Object Oriented Programming (1) ooad lab (6) ooad theory (9) OPEN SOURCE LAB (22) openGL (10) Openstack (1) Operating System CS45 (2) operating systems lab (20) other (4) parallel computing (1) parallel processing (1) PARALLEL PROGRAMMING (1) Parallel Programming Paradigms (4) Perl (1) Placement (3) Placement - Interview Questions (64) PRINCIPLES OF COMMUNICATION (1) PROBABILITY AND QUEUING THEORY (3) PROGRAMMING PARADIGMS (1) Python (3) Question Bank (1) question of the day (8) Question Paper (13) Question Paper and Answer Key (3) Railway Airport and Harbor (1) REAL TIME SYSTEMS (1) RESOURCE MANAGEMENT TECHNIQUES (1) results (3) semester 4 (5) semester 5 (1) Semester 6 (5) SERVICE ORIENTED ARCHITECTURE (1) Skill Test (1) software (1) Software Engineering (4) SOFTWARE TESTING (1) Structural Analysis (1) syllabus (34) SYSTEM SOFTWARE (1) system software lab (2) SYSTEMS MODELING AND SIMULATION (1) Tansat (2) Tansat 2011 (1) Tansat 2013 (1) TCP/IP DESIGN AND IMPLEMENTATION (1) TECHNICAL ENGLISH (7) Technology and National Security (1) Theory of Computation (3) Thought for the Day (1) Timetable (4) tips (4) Topic Notes (7) tot (1) TOTAL QUALITY MANAGEMENT (4) tutorial (8) Ubuntu LTS 12.04 (1) Unit Wise Notes (1) University Question Paper (1) UNIX INTERNALS (1) UNIX Lab (21) USER INTERFACE DESIGN (3) VIDEO TUTORIALS (1) Virtual Instrumentation Lab (1) Visual Programming (2) Web Technology (11) WIRELESS NETWORKS (1)

LinkWithin