Links to sections on this page:
This is a senior-level undergraduate class in computer operating systems.
We will cover the principles underlying the design of various subsystems of
modern operating systems, ranging from process management and virtual memory
to file systems and access control. Instruction in these principles will be augmented
a series of projects in which students develop these subsystems within the
context of an instructional operating system.
- B. Kernighan and D. Ritchie,
C Programming Language,
2nd Edition, Prentice Hall, 1988. (Since the C programming language
is a proper subset of the C++ programming language, if you know C++,
you pretty much know C already. However, things available in C++,
such as strings and streams, are not be available in C. So, you need
to know how to do things such as manipulating
null-terminated array of characters and performing I/O in C.)
- Scott Chacon, Pro Git (a free online book).
You may want to use git when you do your programming assignments.
- Joe Topjian, Unix for the Beginning Mage.
(If you are not familiar with Unix, please read this tutorial as soon as possible.)
- David Rusling, The Linux Kernel.
(This is for your reading pleasure. We will not cover this book in our class.)
Syllabus / Topics Covered
The following schedule and topics are tentative and are subject to change
without notice (and it's based on a 15-week semester).
- Wk 1-2: Introduction to Operating Systems (OSID Ch 1)
- A Brief History of Operating Systems
- A Simple OS
- Beyond a Simple OS
- Wk 3-4: Multithreaded Programming (OSID Ch 2)
- Why Threads
- Programming with Threads
- Thread Safety
- Wk 5-6: Basic Operating Systems Concepts (OSID Ch 3)
- Context Switching
- I/O Architecture
- Dynamic Storage Allocation
- Linking and Loading
- Wk 7-8: Operating-System Design (OSID Ch 4)
- Wk 8-9: Process Management (OSID Ch 5)
- Threads Implementations
- Wk 10-11: File Systems (OSID Ch 6)
- The Basics of File Systems
- Crash Resilency
- Directories and Naming
- Multiple Disks
- Flash Memory
- Case Studies
- Wk 12-13: Memory Management (OSID Ch 7)
- Memory Management in the Early Days
- Hardware Support for Virtual Memory
- OS Issues
- Wk 14: Operating-System Design (OSID Ch 4)
- Virtual Machines
- Wk 15: Process Management (OSID Ch 5)
At the end of very book chapters, there are exercises.
Students should treat them as additional resources.
These exercises will not be collected, graded, or dicsussed, although
students are encouraged to work on them if there is time.
You will be expected to complete a sequence of kernel programming
assignments which develop various components of a real operating system:
process management, file systems, and virtual memory.
All projects will require a fairly strong background in C programming,
which you are expected to pick up on your own. There will be 1 to 2
warmup programming assignments at the beginning of the semester
to make sure that you are up to speed with C and doing multi-threading in C.
All kernel programming assignments are extremely difficult
and can be very very time-consuming.
You can do these assignments in teams of two or three students.
Since the kernel programming assignments are interrelated,
you must pick a team at the beginning of the semester and
stick with the team till the end of the semester.
If you'd prefer, you can do the kernel assignments by yourself.
For more information, please see the projects web page.
A midterm and a final examination will be given.
The date of the midterm examination will be posted near the
top of the class home page.
The date of the final examination is firm and it is also listed near the
top of the class home page.
Any scheduling conflicts regarding the midterm exam date must
be resolved with the instructor at least one week
before the exam date.
Unless otherwise specified, all exams will take place in the lecture class room
of your respective section.
If an exam is to take place in a room different from the lecture class room,
information will be explicited provided in the corresponding item in the
General Information section of the class web page.
I often get questions such as (1) can I get a copy of an old exam
and (2) what types of questions should I expect? The answer to
question (1) is "no". I'm sorry, but I do not give out old exams.
That's just my policy. The answer to question (2) is the following.
There are three types of exam questions that I usually ask.
The first type is a calculation-type question. Pretty much
anything that can be calculated/computed by running an algorithm
can be asked in an exam. For example, I can ask you to compute
a schedule using a particular scheduling algorithm. I can also
ask you to calculate average waiting time for a particular scheduling
policy. (Calculators will not be permitted during exams, but you can
leave your answers as fractions for non-integer answers.)
I may also ask you about what a data structure (e.g., tree, hash table, etc.)
would look like after certain operations have been performed on it.
Usually, for this type of questions, you must get the answer
right and there is not much room for partial credits.
The second type is multiple-choice questions. Unless explicitly
stated, every multiple choice questions has one or more correct answers.
(Even if a question asks, "which statements are correct",
it can have one or more correct answers.)
Please check all the correct ones and don't check any of the incorrect ones.
There is a penalty for selecting incorrect answers (you will lose 1 point
for every such selection). Please note that an incorrect statement
can never be a correct answer (unless the question asks you to
select statements that are incorrect).
The scoring of multiple-choice questions is as follows.
Multiple-choice questions are worth 2 points each and you are
given 5 selections for each such question. It can have 1 to 4 correct answers.
If a multiple-choice question has 1, 2, or 4 correct answers,
for each correct answer that you have selected, the number of points
you will get would equal 2 divided by the total number of correct answers.
If it has 3 correct answers, you will get 1 point for
selecting one of the correct answers and you will get 0.5 point each for selecting
additional correct answers. Therefore, if you mark all the correct answers
and don't mark any of the incorrect answers, you will get 2 points. But
if you have selected incorrect answers, we will subtract 1 point for each
such selected. In the end, if the total score for a problem is below zero,
a score of zero will be assigned.
Let's look at a concrete example. If a problem has 3 correct answers and you
selected 2 correct ones and one incorrect one. You will get 1.5 points
for the correct answers and -1 point for the incorrect answer. So, you
will end up with 0.5 point. On the other hand, if you have only selected
one of the correct answers and didn't select anything else, you will end up with 1 point.
The third type is to ask you to give the best answer
for a given question. (If a question says, "In N words or less...",
it's giving you a hint that the answer should be N words
or less. You don't have to answer in N words or less. There is one
exception though. If the question is of the fill-in-the-blanks
type where N is small, then you must not use more than N words.)
For this type of question, you get credit for including the "best answer".
You may get deductions for including "bad answers".
What you need to demonstrate is that you can distinguish between answers of different quality
and write down the best answer.
(For these questions, there is no need to
write complete English sentences when you answer exam
questions. Just give me the important stuff!)
Let me give a couple of silly examples (with questions
that's not in the scope of any exam).
Can you tell why the first answers above are better than
the second answers?
If a question does not mention weenix explicitly,
you must not give a weenix-specific answer.
Most weenix-related questions are mostly high-level questions, testing about
your understanding of weenix. Although I may ask you about the purpose and
usage of a specific field inside a particular important kernel data structure.
If a lecture slide has a grey X in the lower left hand corner, I will not ask questions from that slide.
If a lecture slide does NOT have the grey X, then it's possible that I will ask questions from that side
(you need to figure out if it's LIKELY that I will ask questions from that slide or not;
please do not ask me whether a particular slide is likely or not because I won't give you an answer for it).
In order to be fair to the entire class, we can only grade based on what you put down on the exam paper.
We must not take into consideration what's in your mind when you wrote your answers. We have to assume
that you wrote what you meant and meant what you wrote.
- "For programming assignments (well, this
is not our policy, I'm just using this as an example),
when is 'plagiarism' considered taking place?
If your answer is "when you take
someone else's work and claim it to be yours", then you
will get full credit. If your answer is, "when you submit
someone else's work", you probably will not get full credit
(since you are allowed to use code given to you in another
class that you have taken if you cite it properly).
- "What is the fairness policy of
this class?" If your answer is, "whatever the instructor
offer to one student, he must offer it to the rest of the
class," then you will get full credit. If your answer is,
"the instructor must be fair to every student," you
probably will not get much partial credit.
In general, better answers may score more points.
If you give very high level and generic answer that's generally true
or basically just repeat the question,
you probably will get very little partial credit for it! You need to
answer a specific question with a specific answer.
On the other hand, if the question called for a general answer and
the answer you gave only applies to some specific examples,
you probably will get very little partial credit for your answer.
You must not give examples to answer general questions.
If I asked a question straight from the lecture slides,
the best/correct answer is the one on the lecture slides.
If you disagree with what's on the slides, you must complain when
you are studying for the exam, i.e., before the exam.
Once the exam starts, it's too late to complain that you don't
like the answer on the lecture slides. In an exam, if you
give an answer that's different from the lecture slides, you
may receive partial credits, at the discretion the TA.
Finally, I reserve the right to ask about things that I think
you should know and not on lecture slides.
I often get questions about how to study for exams. Here's
what I would say about my exams.
I mentioned on the exams lecture slides that
our exams are mainly about "knowledge about course material" AND "critical thinking".
I think a lot of students lost points in multiple choice questions because they were not careful about reading questions and answers.
If you are not very careful in reading multiple choice answers and you select an incorrect answer,
you would lost 1 point and these points do add up.
Since all students in CS 402 are grad students, it's reasonable to ask everyone to "think critically".
For every "wrong" answer in a multiple choice question, if you think carefully (based on your knowledge about the course material),
you should be able to say, "Obviously, this is wrong because of this and that",
i.e., you should be able to form an argument that clearly show that a particular answer is incorrect.
So, you definitely need to know the course material well enough so you can form those arguments.
You also need to read every question and every answer very carefully so you won't choose an incorrect answer.
One thing I would recommend is to form a study group to study for exams.
You can form a study group with your kernel teammates or teammates from another team.
You can come up with your own true/false question when you read lecture slides and ask
other students to figure out whether your statement is true or false.
If someone answered "false", he/she must give an explanation why the answer is false.
If you get into the habit of identifying exactly why a particular statement is false,
I think you will be able to do the same during exams.
The grading breakdown is as follows:
The above percentages will be used to calculate a numeric score.
|| (extra credit)
Two methods will be used to calculate your final letter grade:
Your class letter grade will be the
higher grade based on (1) or (2).
||Use a modified curve (i.e., we won't
necessarily assign an equal number of failing grades as
passing grades) based on the numeric score calculated above
||Use the following fixed scale
(to encourage cooperation and friendly association amongst students):
|91% or higher
Please also note the following:
- No other methods will be considered. (So, please do not ask the
instructor to take how
much you have improved since the beginning of the semester into account.
You are expected to try your best from the beginning!)
- According to the above guidelines, it should be clear that it is possible
to get a grade of C or below for individuals who perform very poorly
(i.e., you should not assume a B- or even C+ if you perform very poorly,
according to the guidelines above.)
However, we hope that everyone will perform well.
- We will not assign incompletes unless you miss the final exam for
documented illness or documented family emergency (in accordance with USC policy).
All project assignments must be turned in on time.
Late submissions will receive severe penalties. Due to clock skews,
electronic submissions of projects assignments will
be accepted within 15 minutes after the specified deadlines without
For a project assignment,
if you submit within the next 24 hours, you will receive 90% of your grade.
Although right after midnight of the submission deadline,
you will lose 1% every 5 minutes.
When the penalty reaches the day limit, it flattens out.
For example, if your submission has a timestamp that is 32 minutes after
the grace period, 7% will be deducted from your assignment after grading;
if your submission has a timestamp that is 1 day, 7 hours, 30 minutes,
and 1 second after the grace period, you will receive a score of zero
(and your assignment will not be graded).
The figure below summarize the deductions for warmup assignment 1, warmup assignment 2, and kernel assignment 3.
For kernel assignment 1 and kernel assignment 2, beyond one day late, you can still
submit and receive a 50% deduction, if you inform the instructor before these assignments are graded.
This goes all the way to the next assignment submission deadline.
The idea here is that since kernel 2 depends on kernel 1, if your kernel 1 is not
working, you may end up spending all your time to get it to work in the next
couple of weeks and have no time to work on kernel 2. This way, you still get
50% of your kernel 1 score and will enable you to complete kernel 2 also at a 50% deduction.
The figure below summarize the deductions for kernel assignment 1 and kernel assignment 2.
(Please note that this policy does NOT apply to kernel assignment 3.)
If you are unable to complete a assignment due
to illness or family emergency, please see the instructor as soon as
possible to get an extension. A doctor's note
is required as proof of illness or emergency.
In general, when you get sick,
it's best to see a doctor and get a note just in case you may need it later.
Note From A Doctor
Recently, there has been a change in the policy at the
Student Health Center regarding giving a "note from the doctor"
for you to bring to a faculty
member so that you can be execused from deadlines. Basically,
they will not give you such a note any more.
What they would give you is an Authorization for Disclosure
of Medical Information form. With this form, you give them
permissions to discuss your illness with me.
So, if you visit a doctor at the Student Health Center,
please make sure you fill out one of these forms, check the
"limited discussion with faculty" checkbox, get it stamped,
signed, and dated by someone there (a clerk/receptionist
would sign at the "witness" line), and bring it back to me.
This would satisfy the "note from a doctor" requirement so
that you can get an extension.
If you visit a doctor somewhere else, please either bring a
"note from the doctor" or a similar authrozation letter so
I can contact them.
All requests to change grading of programming assginments
must be submitted in writing within one week
of the time the initial grade was announced to you. Requests must be specific
and explain why you feel your answer deserves additional credit.
A request to re-grade an assignment can result in the entire assignment
being re-evaluated and as a result the score of any part of
the assignment be increased or lowered as appropriate.
If you have made multiple submissions and after you have received your grade
and you noticed that what we graded wasn't the submission you wanted us to
grade, you may ask us to to grade a different submission. In this case, we
will deduct 20 points. By default, we will grade the last submission.
What you should do is to go through the verification procedure
and make sure that we are grading the submission you want us to grade.
If you discover that the submission we are grading is not the one you want us to
grade and if you tell us soon after grading starts, there would be no penalty.
Each TA is required to use one standard when grading all the exams in
his/her section. Therefore, regrade for exams is not about arguing for points
but about whether the TA has made a mistake in grading or not. If you think the
TA has made a mistake, you should write down (on the cover page of the exam)
which problem/subproblem needs to be regraded and why you think the TA has made
a mistake. Plese limit the description of your rationale to be only one sentence
long (e.g., "my answer is also correct", "I deserve more partial credit", etc.).
There is no need to discuss your answer or your rationale with the TA
since the TA is required to grade entirely based on what you wrote
on the exam paper (and thus must ignore everything you said during a regrade session).
Please be familiar with the grading rules for multiple choice questions.
The TA must stick to those rules when giving points for multiple choice questions.
After the regrade appointment is over, the TA will look over your answers in
order to determine if a mistake was made (i.e., the actual regrade only happens
after your regrade appointment). If a mistake was made, the TA will
need the instructor's approval in order to return points to you.
If I approve of a grade change, I will send you a private e-mail
informing you that I have updated my grading records.
Please understand that if your grade stays the same, I will not send you an e-mail.
Therefore, if you don't get such an e-mail from me, it means that your grade did not change.
To be fair to all, we must assume that you wrote what you meant
and meant what you wrote. Every student gets a maximum of one regrade
appointment. So, please use your time wisely during a regrade session and not
spending much time telling the TA what you were thinking when you were writing
down your answers since the TA must grade based on what you wrote and not what you were thinking..
My office hours are held two hours each week. Please feel free to come to chat
with me to clarify lecture material and get hints about programming assignments.
You do not need an appointment to see me during office hours.
Regarding lecture materials, please understand the purpose of office hours is to clarify lecture materials.
I will not repeat lecture materials during office hours. If you miss a lecture, it's your responsibility to
figure out how to make up for the missing lecture materials. Since lectures are recorded for the DEN section,
you should review DEN lecture videos before you ask me to clarify lecture materials.
If you need to see me outside of office hours, it's best that you make an
appointment (and reserve a timeslot) so I can make sure to be in my office when you visit.
Making an appointment is not a big deal! Just send an e-mail to me and tell me
when you are available to meet and go from there.
There are three ways to get extra credit in this class.
When calculating your extra credit points for programming assignments,
we apply the early submission extra credit first (by multiplication)
and the Google Group extra credit at the end (by addition).
- Post timely (i.e., within 24 hours of the original post), useful, and insightful answers to the
class Google Group
in response to questions posted by other students regarding
kernel programming assignments.
- The maximum number of extra credit points
you can get is 10 points for each of the kernel assigments
(on a 100-point scale).
- You can lose extra points you have earned if you post something
unprofessional to the class Google Group or exhibit poor
Please always be courteous and professional.
- The instructor (or the TA)
will decide to award extra credit or not at his discretion and
will keep track of scores. (Harrassing the TAs or course producers is considered
- You probably won't get extra credit points if you repeat exactly what others
have already posted (so, you should always try to add something useful to what
others have posted).
- You probably won't get extra credit points if you respond to a post
24 hours beyond the time of the original post (unless you have something
very insightful to add).
- If you want to be considered for extra credit, you have to reply to an existing post
(i.e., do not start a new thread).
- You definitely won't get extra credit points if you respond to a post
via private e-mail.
- If you post something good, it's your responsibility to verify that it
has been posted to the Google Group.
- To encourage you to do your programming assignments early,
you will get extra credit if
you turn in programming assignment 2 or 3 days early.
The figure below summarize the early submission extra credit schemes.
- If your submission is more than 72 hours before the posted deadline,
you get an extra 10%, i.e., your actual score will be 1.1 times your
graded assignment score.
- If your submission is between 48 and 72 hours before the posted
you get an extra 5%, i.e., your actual score will be 1.05 times your
graded assignment score.
- Earn class participation extra credit.
Please note that due to my fairness policy,
I cannot offer any individual extra credit work.
Implicit Student Agreement
Unless otherwise specified, programming assignments and exams must be that of the individual student
(for group programming assignments, the work must be completely that of the group members).
It is often productive to study with other students. However, if any portions of the
programming assignments are found to be shared between two (or more)
students, zero credit will be given to all students concerned and all students
will be disciplined. This policy is in the interest of those students who
do their own work, which hopefully applies to all of you in this class.
This policy also holds for programming assignments. In
this class, we will use sophisticated automated program checkers to detect
cheating. Be aware that the program checkers have demonstrated very good
results and are widely used within the academic community. Any student
caught cheating will be given zero credit and will be disciplined.
It is the students responsibility to submit their assignments
electronically in time.
For students who satisfied the prerequisite at other universities
or through work experience, this course assumes that you understand
data structures, basic algorithms, and UNIX programming. You should
be able to write large programs in C. No special assistance or
consideration will be offered if your background is inadequate.
During the semester you are responsible for completing the assigned
readings, programming assignments, and exams.
You must keep up with the assigned readings.
If you come to class without having read the chapter for the
corresponding lecture, you're unlikely to learn anything at all from the lecture.
- You are expected to read the relevant textbook chapter thoroughly.
Not all details will be covered in class, and the exam may test material
covered in the textbook but not discussed in class.
- I expect you to attend every class meeting.
If you do happen to miss a session, you are responsible for finding out
what material was covered and if any administrative announcements were made.
Also, please be aware that all exams (in the summer session) are in-class,
so you will be expected to at least attend those lectures.
The instructor must treat all students equally and cannot
give special treatment to any particular student.
Therefore, please do not ask special favors from the
instructor because of your circumstances.
This may seem unfair to you because you believe that your
circumstances are special (understandably, everone does).
Other than the exceptions setup at the beginning of the semester (mostly for "remote DEN" students),
the rule the instructor must follow is that whatever
he offers you, he must offer to the entire class.
Auditing "unofficially" is not permitted for this class.
E-mail is a serious communication tool. For this class, you should
setup your e-mail server so that you do not drop any e-mail from me.
Pretty much all class related announcements will be sent through the
class Google Group.
Therefore, you are required to be a member of this Google Group.
As messages are posted to the class Google Group, you will receive e-mail
notifications and you should read all these class-related e-mails.
Please see instructions on how to get
on this group (you should do this as soon as possible).
You are strongly encouraged to send private e-mail messages to me if you have questions
about programming assignments or lectures. If the answer is appropriate for the entire class,
I would normally anonymize the reply and send the reply through the class Google Group and bcc
a copy to you. So, please don't be shy to ask questions!
One type of question I often get over e-mail or see in the class Google Group is:
Here is my understanding of X. Am I right (or is this correct)? Correct me if I'm wrong...
Although this type of question is perfectly fine during office hours, this is really not a good way
to ask questions over e-mail. If no one corrects you, you must not conclude
that you were correct! If you see "X" defined or described in lecture slides or in the textbook,
you should try to understand why it was stated that way.
A better question to ask over e-mail would be to ask about why it was stated that way.
Another type of question I often get is the following:
I am thinking about not following the spec or grading guidelines and would like to do this instead.
Is it acceptable (or is this okay)?
What you are really asking is whether you will receive full credit or not.
Please just stick to the spec and the grading guidelines.
Academic Integrity Policy
Please make sure you read the Academic
Integrity Policy of this course.
The diversity of the participants in this course is a valuable source of ideas, problem solving strategies, and engineering creativity.
I encourage and support the efforts of all of our students to contribute freely and enthusiastically.
We are members of an academic community where it is our shared responsibility to cultivate a climate where all students and
individuals are valued and where both they and their ideas are treated with respect, regardless of their differences, visible or invisible.
A link to the
USC Summer 2018 academic calendar
is provided here for your convenience.
A link to the
USC Summer 2018 CS schedule of classes
is provided here for your convenience.
(These resources below are provided for your information.
Please note that the instructor has not read most of them.
Please use these resources at your own risk!)
- C Programming
(by Steve Holmes at the University of Strathclyde in Glasgow, England)
- includes notes on make, separate compilation,
file I/O, etc.
- Makefile tutorial (at Colby College)
- Steve's Software Trek
(by Steve Karg) - includes some useful C/C++ source code for string
manipulation, INI file manipulation, etc.
- C Examples -
lots and lots of sample C code for basic stuff.
- C/C++ at USC
from USC ITSWeb
- Online Judge
online portal for IT interview
Just for fun (not all that related to our class):
- Ubuntu Linux
- cygwin (BSD system with X11R6 on Windows XP)
- Some Often-used UNIX Commands
- Unix commands (more complete, from University of Utah)
- UNIX Shell Programming (Chapter 2 of this book gives a good introduction to UNIX)
UNIXhelp for Users from the University of Edinburgh
UNIX Tutorial for Beginners from the University of Surrey
Introduction to the Unix Shell from the Canisius College
Introduction to C Shell Programming from the Canisius College
(compiling, linking, additional libraries, include files) from USC ITSWeb
Understanding C by learning assembly
- UNIX Documentation
(concepts, commands, X-Windows) from USC ITSWeb
- Editors on most UNIX systems
- Beej's Quick Guide to GDB
- Richard Stallman's gdb Tutorial
- GPROF Tutorial - How to use Linux GNU GCC Profiling Tool
- USC ITS Resources
- General information on operating systems, productivity applications,
Internet connectivity, e-mail and web publishing at USC, can be found
at the ITS software site.
You can click on your operating system and download useful software from there.
For example, for the Windows platform, you can find things like
X-Win32 and FileZilla there (looks like the very popular PuTTY
is no longer available for downloads from ITS, but you can get it from here).
- UNIX Computing Accounts for Students (SCF).
- Examples of using ssh and sftp at usc
(replace "mizar.usc.edu" with "nunki.usc.edu" when doing our warmup programming assignments).