Operating Systems CIS 657

Operating Systems CIS 657
Any change in the submission format will cause deduction of points.
1. A single pdf file that includes the following:
Codes of every file you edited highlighting in yellow the changes for all Questions in
addition to a screenshot of the output.
2. A zipped folder for the code for each question.
3. A single video file that shows short code overview and the output running
Question 1:
In this question, you are required to simulate the starving problem that a process may suffer if all other
processes in the system have higher priority than its priority.
It is required to create at least two processes (P1 and P2) with priorities 40 and 35 for example. You
should create a third process (Pstarv) with less priority such as 25.
You need to put P1 and P2 in the sleep state every couple of seconds to simulate a context switch
between P1 and P2. When P1 sleeps, P2 will run and when P2 sleeps, P1 will run. Until now, Pstarv will
not be able to run since its priority is the lowest priority. You need to fix that. You are required to
change/update/increase the priority of Pstarv each time a context switch occurs.
So, after a number of context switches, Pstarv will finally be able to run to print its ID and print a
celebration message that it is finally running and celebrate that you will get a good grade as well.
Feel free to assume any missing information such as should you have a flag or an argument to decide
which process you are interested to avoid starvation, should you use shell commands or not, should you
increase the Pstarv priority by 1 or by 5…..… etc.
P1 and P2 are not supposed to know anything about the Pstarv process. Do not hardcode it inside P1 or
P2. So, you should not include the code of increasing the Pstarv priority in P1 nor P2.
Question 2:
You can think of the starvation problem in Question 1 but instead of incrementing the priority of the
Pstarv every time a context switch occurs, the priority increment of Pstarv should occur every two
seconds the Pstarv process is in the ready queue without getting the CPU.
To demonstrate this feature, you are required to just increment and print the “Pstarv priority” every two
seconds based on the clock and the clkinit (not the sleep function/system call).