CS 3733 Operating Systems, Spring 2003 Assignment 1 Comments

This assignment was graded on a basis of 30 points.
The results were disappointing as some students thought their programs were working, but they were not. Fewer than half of the students who checked the box indicating that everything was working correctly got full credit.

The sleeper program was designed to help you test your programs. Many students had no idea what the output of their programs should look like when run with the test files. You should not assume your program is working just because it produces output.

In order to test your programs, you must understand what they are supposed to do and what the output should look like. In Part 2, all of the children should be created and started running before the main (parent) process blocks. If there are still input lines available, then only waitpid with the WNOHANG option should be called.

Some general comments:

• You should be suspicious if your program reports the exit status of a child before the child has completed.
• You must use the macros to determine the exit status (return value) of the child.
• If the child exits normally with return value 0, then status will be 0.
• In any other case, status will be nonzero.
• First use WIFEXITED to see if it exited normally. Only in this case can you get a return value with WEXITSTATUS.
• The value you report as the exit status of sleeper should agree with the second parameter to sleeper.
• There should not be any lint warnings that you do not understand.
• 4 things you can do if you do not know what busy waiting means:
  1. Ask someone (like your instructor)
  2. Look it up in the index up PUP
  3. Look it up in the index up the Silberschatz book
  4. Do a Google search