Due Date: February 7, 2019 [2019-02-07, Thursday of week 04]
The following guidelines are expected for all homework submissions:
- All homework must be typed. Homework which is not typed will be returned ungraded and will be
subject to the late homework guidelines as set out on the syllabus page. PLEASE DO NOT scribble
something on lined paper and rip it out of your spiral notebook — hanging chads went out
with the presidential election in 2000.
- I don't care too much about what font you use or how large your margins are; however, you might
want to check out a monospaced font for typing code, as it will be easy to see the indentations.
- Speaking of indenting, PLEASE DON'T USE TABS TO INDENT YOUR CODE. Tabs can often get interpreted
differently by different computers and applications, and could make code that is nicely formatted
on your computer look
all over the map on my computer or printer. USE SPACES INSTEAD.
You can set up almost every modern text editor to insert spaces whenever you press the TAB key, or
you can simply pound the spacebar.
- Work with a partner. I can't stress this enough; part of this policy is don't
split up the work – WORK TOGETHER on the assignment. This activity mimics
an industry code development model called
pair programming which is part of the Extreme
Programming software development method. Feel free to collaborate in your pairs as much as you
want, doing the entire assignment together.
- DO NOT share your work between groups. Doing so will count as plagiarism. If you wish to discuss
solutions with another group over coffee in the Lair, that's fine as long as it is kept at the
conceptual and you don't share your code between groups. Each group needs to turn in its
own version of the solutions.
- You only need to turn in one copy per group.
- Submit your homework through GitHub, in your repository, and be sure to make
me a contributor so I have been allowed access. I cannot evaluate what I
cannot see! If I cannot upload to your repo, you will not get a grade for the assignment.
Problems for Assignment #1
- What is the difference between an operating system and middleware?
- What is the relationship between threads and processes?
- Of all the topics previewed in chapter one of the text book, which one are you most looking forward
to learning more about? Why?
- Suppose thread A goes through a loop 100 times, each time performing one disk I/O operation, taking
10 milliseconds, and then some computation, taking 1 millisecond. While each 10-millisecond disk
operation is in progress, thread A cannot make any use of the processor. Thread B runs for 1 second,
purely in the processor, with no I/O. One millisecond of processor time is spent each time the
processor switches threads; other than this switching cost, there is no problem with the processor
working on thread B during one of thread A's I/O operations. (The processor and disk drive do not
contend for memory access bandwidth, for example.)
- Suppose the processor and disk work purely on thread A until its completion, and
then the processor switches to thread B and runs all of that thread. What will
the total elapsed time be?
- Suppose the processor starts out working on thread A, but every time thread A
performs a disk operation, the processor switches to B during the operation and
then back to A upon the disk operation's completion. What will the total elapsed
- In your opinion, which do you think is more efficient,
- Find and read the documentation for
pthread_cancel(). Then, using your
programming environment, use the information and the model provided in Figure 2.4 on page 26 of the
text book to write a program in which the initial (main) thread creates a second thread. The main
thread should read input from the keyboard, waiting until the user presses the Enter key. At that
point, it should kill off the second thread and print out a message reporting that it has done so.
Meanwhile, the second thread should be in an infinite loop, each time around sleeping five seconds
and then printing out a message. Try running your program. Can the sleeping thread print its
periodic messages while the main thread is waiting for keyboard input? Can the main thread read
input, kill the sleeping thread, and print a message while the sleeping thread is in the early part
of one of its five-second sleeps?
- Suppose a system has three threads (T1, T2, and T3) that are all available to run at time 0 and need
one, two, and three seconds of processing, respectively. Suppose each thread is run to completion
before starting another. Draw six different Gantt charts, one for each possible order the threads
can be run in. or each chart, compute the turnaround time of each thread; that is, the time elapsed
from when it was ready (time 0) until it is complete. Also, compute the average turnaround time for
each order. Which order has the shortest average turnaround time? What is the name of the scheduling
policy that produces this order?
- Google the
C standard library API and find out how to get information from the command line
by using a
printf() call to display a prompt, then another call [which you will look
up] to get the user input. Write a program in
C to prompt the user demographic information
including name, age, class year, and any three other data times you wish. Structure the program as
call-and-response program such that each data item is a single question with a single
answer. When all data has been obtained, display the data on the console. Each data item must be
on a separate line, and it must be appropriately labeled. The output must be done using a single