[SOLVED] C COMP 3500 Lab 2 Assignment

COMP 3500 Lab 2 Assignment
Instructions This lab assignment explores the data shared problem and process synchronization using Petersons solution.
Objectives of this assignment:
to work on a Unix based system
to dust off your programming skills in C
to understand the fork() function to create achild process
to understand the relationship (or lack of) between parent and child process
to experience the data shared problem
to deploy the Petersons solution to address the data shared problem
IMPOR T AN T:
1) Y our code will be tested and graded REMO TEL Y on the Engineering Unix ( T ux) machines. If the code does not work on those machines, you will not get any credit even if your code works on any other machine.
2) A late submission will get a 50% penalty if submitted right after the deadline. The next day, you cannot submit the lab.
3) Onesubmissionpergroup.
4) Writing and presentation of your report are considered to grade your lab (30%). Your conclusions must be
supported by the data/measurements you collect.
5) The quality of your code will be evaluated (80%).
6) Questions about this lab must be posted on Piazza if you need a timely answer benefiting all
students.
Use this file to answer the questions. Highlight your answers
Part I: Programming on Tux machines (10 points) Program Exercise 1:
Exercise 1: Download the program lab2-1.c. Compile it and execute it. Observe the code and observe the output. This program has a parent and child processes sharing a variable. This program is intended to increment the shared (common) variable counter *countptr. The parent process is supposed to increment *countptrbyincrementsof20whilethechildincrementsby2s. Asatisfactoryexecutionofthisprogrammay be: the child increments the counter *countptr twice (reaching 4), then the parent increments the counter *countptr thrice to reach finally 64. Answer the following questions:
1) Does the program really execute as supposed (or intended)? Justify/Explain
2) Is the variable *countptr really a shared (common) variable? In other words, are the changes made to *countptr by the child visible by the parent, and vice versa? Explain.

COMP 3500 Lab 2 Assignment
(90 points) Program Exercise 2:
The program lab2-2.c creates a genuine shared variable *countptr. Download, compile, and execute this program.
1)
2)
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Based on the execution, show that *countptr is now a genuine shared variable (countptr points to a zone shared by the parent and the child). Now, are the changes to *countptr made by the child visible by the parent?
Does the program really execute as supposed (or intended), i.e, the counter increases exclusively in increments of 2 or 20? Explain what is happening.
Without modifying the routine add_n(), use the Petersons solution to correct the program lab2-2.c. to execute as intended: the variable should increase by 2s or twentys
Hint: Besides the pointer countptr used to point to the shared memory zone, you need to map three other integers Interested[2] and Turn (Petersons variables); These variables may be shared exactly the way that the zone pointed by countptr is shared.
What to turn in? Electronic copy
Turn in separate files:
1) This file with answers when applicable
2) Program lab2-2..c (corrected)
3) A short report
A penalty of 10 points will be applied if these instructions are not followed.
1) Your report must:
a. state whether your code works. If is does work, state any issues you are aware of.
b. Good writing and presentation are expected.