Create a disk scheduling simulator in C. Your program disksked will accept a starting track number and eight tracks to read. disksked will simulate FCFS, STFS, SCAN and C_SCAN and produce a report of which tracks will be read in which order and the amount of head movement for each track.

Learning Objectives

Demonstrate understanding of the four disk scheduling algorithms documented in the text.

For each scheduling algorithm, correctly output (in order) the tracks to be read, the amount of head

movement for each track read and the total head movement for all eight tracks.

Assignment

Create and edit disksked.c using the text editor of your choice. Here are the basic requirements for disksked.c:

Usage: ./disksked START T1 T2 T3 T4 T5 T6 T7 T8 

START is the current track of the disk read-write head.

T1-T8 are tracks to be read. Your disksked must process exactly eight track values.

All track values tested for grading will be integers between 0 and 256

All track values are read by your program from the commandline as shown above.

You are to emulate the following disk scheduling algorithms with the following modifications where noted:

First Come First Served (FCFS) Tracks are processed in the order received, from the starting track to each of the 8

tracks in order on the command-line from left to right.

Shortest Seek Time First (SSTF)

Tracks are processed from the absolute value of the shortest distance from the current track, beginning with the starting

track.

If there are two tracks that are equal distance from the current track, choose the first one (the earliest one in the list) and

move there first.

SCAN

Re-order the tracks, so that from the current track, move to higher numbered tracks

first, then reverse to the lower tracks. Process all of the higher numbered tracks in ascending order, then move to the

lowest numbered track and process the lower numbered tracks in ascending order.

Do not move to track 0 or to the end of the disk during your scan. Some of you might recognize this variant of the SCAN

algorithm as the LOOK algorithm.

Circular SCAN (C-SCAN)

Re-order the tracks, so that from the current track, move to higher numbered tracks

first in ascending order (as in SCAN), but then reverse direction and process the lower

numbered tracks in descending order.

Some might recognize this variant as the C-LOOK algorithm.

Generate a report that contains four lines, in this order: FCFS, SSTF, SCAN and C_SCAN.

For each algorithm simulated, output (all on one line):

the algorithm name followed by a colon and a space

"Start:" followed by the starting track number and a space

the eight tracks in order of processing, each followed by a colon and the count

of tracks needed to move to that track, each followed by a single space

"Total:" and the number of total tracks moved during the simulation.

Sample Output

name@name-Ubuntu:~/cs3100/lab6$ ./disksked 53 98 183 37 122 14 124 65 67 FCFS: Start:53 98:45 183:85 37:146 122:85 14:108 124:110 65:59 67:2 Total:640 SSTF: Start:53 65:12 67:2 37:30 14:23 98:84 122:24 124:2 183:59 Total:236 SCAN: Start:53 65:12 67:2 98:31 122:24 124:2 183:59 14:169 37:23 Total:322 C_SCAN: Start:53 65:12 67:2 98:31 122:24 124:2 183:59 37:146 14:23 Total:299 name@name-Ubuntu:~/cs3100/lab6$

Files

Here is a list of the files created or modified in this lab:

disksked.c

Additional Requirements

Please write this program as simply as possible. Do not add any prompts, output or any file I/O except as specified. It is ok for you to generate debugging information while you are testing but use an environment variable as a flag so that I don't see any extraneous output when I run your program. Ask about this if you have questions. Alternatively, simply remember to remove all instrumentation prior to turning in your assignment. Your grade will depend on your adherence to these requirements.

Upload only disksked.c to