• Concordia University

• COMP 346

COMP 346: Operating Systems - Winter 2020

Instructors: Dr. Aiman Hanna, Dr. Hakim Mellah,

Prof. Kerly Titus

24-hour Take-home Final Examination

Submission Due date and time (EXACT):

Wednesday, April 22nd 9:00 AM EST

Exam Rules: Please read very carefully:

1. General Information

Date and time of exam release: Tuesday, April 21, 2020 at 9:00 AM EST

Deadline for exam submission: Wednesday, April 22, 2020 at 9:00 AM EST

Exam is a 24-hours exam. You must submit your solution by 9:00 AM on Wednesday April 22. Submission

received at, or after 9:01 AM EST, will be rejected and a FNS grade will automatically be issued for the course.

[In fact, the system will reject any submissions beyond 9:00 AM EST]. After the exam, you may be called for

an oral evaluation. If you are called for an online oral evaluation, you MUST present yourself for this

evaluation. Failing to do that will result in your grade being suspended and eventually an FNS grade is assigned.

Quality of Submission: You will be marked based on correctness, comprehension, completeness and quality

of produced work.

Submissions: You need to submit your solution in a file named <Your-ID#_Your-Name>.pdf (or .doc. These are

the only two allowed formats). For instance: 9080332_Mike_Simon.pdf. The file must include you name, ID,

and you must sign it. The solution MUST follow the order of the questions (i.e. Question 1 solution, then

Question 2, etc.). You must submit that file to Moodle of your section under the titled: Final Exam Submission.

 VERY IMPORTANT: You will also need to sign this exam document itself and include it with your

submission as well. Your exam will not be marked unless this exam is signed and returned back.

If we do not submit these two signatures; we will have to ask you for it manually before your exam can be

considered. This request will cost you 10% of the mark (no exceptions will ever be considered)! So; in simple

words, return the exam signed, and return the answer document signed.

2. Terms and Conditions

The exam is an individual exam. The Exam is open-book. You can consult any materials, including textbooks,

notes, Moodle materials, tutorial notes, and online materials. However; you are NOT permitted to

communicate with any persons neither offline nor online (or through any other type of communication),

including your classmates.C o m p 3 4 6 – T a k e - h o m e F i n a l E x a m i n a t i o n © C o n c o r d i a U n i v e r s i t y – W i n t e r 2 0 2 0

N o P u b l i c a t i o n s o r c o p y i n g a l l o w e d w i t h o u t w r i t t e n p e r m i s s i o n f r o m A L L

i n s t r u c t o r s . - P a g e 2 | 10

In simple words, plagiarism will NOT be tolerated under any conditions and it will officially be reported to

the University for disciplinary actions.

3. Questions that arise during the exam

It is important to note that there will be no support from the instructors or the TAs during the exam. The exam

contents are clear; however, in case you find anything ambiguous, you must express your assumptions very

clearly and continue with the solution. We may however send you some announcements if needed through

Moodle and the mailing list, so you should check from time to time. In simple words, Avoid hesitations! The

text of the exam is very clear and the requirements are detailed carefully. You should not send requests to

your professors requesting clarifications. They may not even have a chance to see these requests on-time.

4. Academic Integrity

Concordia University takes academic integrity very seriously and expects its students to do the same.

You need to declare and sign the following:

I understand that any form of cheating, or plagiarism, as well as any other form of dishonest behaviour,

intentional or not, related to the obtention of gain, academic or otherwise, or the interference in evaluative

exercises committed by a student is an offence under the Academic Code of Conduct.

I understand that the above actions constitute an offence by anyone who carries them out, attempts to carry

them out or participates in them.

By way of example only, academic offences include:

• Plagiarism;

• Contribution by a student (or anyone else) to another student’s work with the knowledge that such work may

be submitted by the other student as their own;

• Unauthorized collaboration;

• Obtaining the questions or answers to an exam or other unauthorized resource;

• Use of another person’s exam during anexam;

• Communication with anyone (in any shape or form) during an exam and any unauthorized assistance during an exam;

• Impersonation;

• Falsification of a document, a fact, data, or reference.

For more information about academic misconduct and academic integrity, refer to the Academic Code of

Conduct and Concordia University’s Academic Integrity webpage.

I have neither given nor received unauthorized aid on this exam and I agree to adhere to the specific

Terms and Conditions that govern this exam.

Exam is ©Concordia University. I will NOT publish this exam (or any extracts or texts of it) in any form

or shape online or elsewhere, or pass it to anyone in any form or shape, neither now nor at any future

point. I understand that publications of this exam requires prior written permission from ALL instructors

of the course and that this permission is NOT given at this time.

Student Name Signature:

----------------------------------

ID #: -------------------------------- ----------------------------------C o m p 3 4 6 – T a k e - h o m e F i n a l E x a m i n a t i o n © C o n c o r d i a U n i v e r s i t y – W i n t e r 2 0 2 0

N o P u b l i c a t i o n s o r c o p y i n g a l l o w e d w i t h o u t w r i t t e n p e r m i s s i o n f r o m A L L

i n s t r u c t o r s . - P a g e 3 | 10

Question 1: [10 Points]:

Assume a system that is capable of supporting multiprogramming, where the following measures are

defined:

- Turnaround Time: Total time to complete a process;

- Throughput: Average number of processes completed per time period T, which is defined as 12ms

(milliseconds).

- CPU Utilization: % of time where CPU is being utilized (not idle) before N processes are

completed.

- Wait Time: Total amount of time a ready process (a ready process is a process that requires CPU

execution) is waiting (for the CPU) from the moment it is ready until it terminates.

Assume that all processes in the system have similar behavior, where a process spends ½ of its time

performing I/O and ½ of the time performing execution. The system is capable of overlapping execution

time for a process with I/O time of another. The system is utilizing also RR for scheduling with a time

quantum of 3ms (ignore context switch time; i.e. assume it takes 0 ms). Show the Gantt Chart for all your

answers.

A) Assume that each process has a total time of 48ms, and for each period of 12ms, each process

does/perform an I/O for the first ½ of a period (6ms), then follows with CPU operations (execution)

during the 2nd ½ of a period (6ms). All processes arrive at time t=0.

i) Which number of running process (1 process, 2 processes, or 4 processes) produces best CPU

utilization? Show all your work.

ii) What is the throughput if 2 processes are running?

iii) What is the average wait time if 4 processes are running? Give the wait time for P1, P2, P3 and

P4.

iv) What is the average turnaround time for 4 processes? Give the turnaround time for P1, P2, P3

and P4.

B) Now assume that four processes, P1, P2, P3 and P4, will run, and all of them arrive at time t=0. Each

of these processes has a total time of 24ms, with the exception of P4, which has 60ms. Assume

also that for each of these processes, the first and last quarter of a period (that is the first and last

3ms) are I/O, and that the second and third quarters are executions.

i) What is the system throughput?

v) What is the average wait time for the processes? Give the wait time for P1, P2, P3 and P4.

ii) What is the CPU utilization (during the time these processes are running until they terminate)?

iii) What is the average turnaround time for the processes? Give the turnaround time for P1, P2, P3

and P4.C o m p 3 4 6 – T a k e - h o m e F i n a l E x a m i n a t i o n © C o n c o r d i a U n i v e r s i t y – W i n t e r 2 0 2 0

N o P u b l i c a t i o n s o r c o p y i n g a l l o w e d w i t h o u t w r i t t e n p e r m i s s i o n f r o m A L L

i n s t r u c t o r s . - P a g e 4 | 10

Question 2: [8 Points]:

Given the following code, where id indicates a process number (or ID), launch() indicates concurrent start

of the processes passed on its parameters, and N is an integer representing the number of processes that

will be launched (i.e. processes that will run on that system).

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