Spring 2012»CSCI 340 Homework 2

CSCI 340 Homework 2

Assigned Date: Wednesday, Feb. 8, 2012
Due Date: Monday, Feb. 20, 2012
Due Time: 10:50am

Last modified on February 20, 2012, at 12:16 PM (see updates)

This is a solo assignment. You must work alone.

Purpose

This assignment focuses on Process Management with C, and in particular:

  • Learn and apply the C programming language for systems development (on Unix environments).
  • Understand the concept of process (vs. thread), as well as key elements of process description and control, states, and scheduling algorithms.

Assignment

Create a process management simulation in C that implements a First Come First Serve (FCFS) scheduler.

Read in process information from an ASCII file. The name of the file will be provided as input to your program, using C command-line arguments.

int main(int argc, char *argv[])
(
   // argc equals the number of arguments received
   // argv is an array containing all command line arguments
   // argv[0] is set to the name of the program
}
 

For example, see [1].

Input

The first line of the input file contains the number of processes that will be used in the simulation.

Each subsequent line of the input file will contain 3 integers describing a single process to be run. The first integer is the process ID, the second integer is the arrival time of the process, and the third integer is the required execution time of the process (remember, we are simulating execution). You should ignore anything past the third integer on each line (e.g., we may use this feature to implement input-file comments). The file may contain an arbitrary number of processes.

Example file contents:

3        # number of processes to schedule
0 1 4    # first process has ID=0, arrives at second 1, and needs 4 secs of CPU time
1 3 2    # ...
2 6 7
 

You may only assume that processes are sorted by arrival time.

Details

Processes and their related information should be stored in ProcessBlockRecords (PBR) organized as a queue in order of their arrival time. The PBRs should be represented as C structs, and the queue as a dynamic array.

struct PBR
{
   int processID;
   int processArrivalTime;
   int remainingRunTime;
};
 

Instead of maintaining actual time in your program, you should use a counter and treat every increment made as the passing of 1 second.

Simulation time starts at 0 seconds.

In a real system, each process would perform some sort of work while executing, but, for simplicity, this simulation will omit this.

Scheduling

For now, implement First Come First Serve (FCFS) to allocate the CPU to the processes. There will be no time quantum/slice, therefore the implemented algorithm will be non-preemptive.

Output

Your program should output the following for each process:

Process n was allocated the CPU at time p seconds.
Process n completed at time q seconds.
 

where n, p, q are int values.

Upon completion of the simulation, i.e., when all processes have finished executing, your program should output the following statistics:

Simulation Statistics:

Average wait time: x seconds
Average turnaround time: y seconds
Average execution time: z seconds
 

where x, y, z are float values.

Average wait time: Average (across all processes) of elapsed time between a process' arrival time and the moment it is allocated the CPU.

Average turnaround time: Average (across all processes) of elapsed time between a process' arrival time and its completion.

Average execution time: Average of all the processes' run times.

So, for the above input example, the output should be:

Process 0 was allocated the CPU at time 1 seconds.
Process 0 completed at time 5 seconds.
Process 1 was allocated the CPU at time 5 seconds.
Process 1 completed at time 7 seconds.
Process 2 was allocated the CPU at time 7 seconds.
Process 2 completed at time 14 seconds.

Simulation Statistics:

Average wait time: 1.0000 seconds
Average turnaround time: 5.3333 seconds
Average execution time: 4.3333 seconds
 

Documentation

Follow the Golden Rule of Style: "A program should be as easy for a human being to read and understand as it is for a computer to execute." [2]

In general, you should comment any variable, obscure statement, block of code, etc. you create.

Also, you should comment why something is being done, e.g.,

numStudents += 1;   /* we have processed one more student */
 

as opposed to how it is done, e.g.,

numStudents += 1;   /* increment numStudents by one */
 

Finally, your code should always include opening comments as follows.

(NOTE: Angle brackets signify information that needs to be filled out. Remove the angle brackets!)

/*
   Author:     <Your Name(s)>
   Email:      <Your email address(es)>
   Class:      CSCI 340, Section 1
   Assignment: HMWK2
   Due Date:   <The assignment's due date>

   Certification of Authenticity <remove one of the following>:     

      I certify that this lab is entirely my own work.

      I certify that this lab is my own work, but I received
      some assistance from:  <Name(s)>

   TASK:   <Provide a simple, yet complete description of the task being
           performed by this program. It may be several sentences long.>

   INPUT:  <Describe the input to this program.  Be thorough.>

   OUTPUT: <Describe the output to this program.  Be thorough.>

*/

 

Submissions

You will submit your assignment via the stono submit command, as follows:

% submit csci340 hmwk2 fcfs.c

or as follows (if you include a C header file):

% submit csci340 hmwk2 fcfs.c fcfs.h

No other submission mechanism will be accepted (e.g., email).

Grading

Your assignment will be graded based on the documentation, formatting, and correctness of your source code. Also the completeness / thoroughness of your work, and how well you followed the homework instructions.

Reference

  1. Cprogramming.com, Accepting command line arguments, accessed on-line, March 20, 2011.
  2. Cooper, D. and Clancy, M. (1985) "Oh! Pascal", 2nd ed., W.W. Norton & Company, New York, p. 42.