COMP 3000 Test 2 Study Guide 2011

Key Concepts

For this test, you should understand the following terms and how they interrelate:

• execve semantics
• how command line variables are processed by execve
• how environment variables are processed by execve
• signal handlers
• concurrent operation with fork
• scheduler and relationship to system calls
• priority scheduling
• round-robin scheduling
• mutual exclusion
• semaphores
• basic pthreads
• System V init scripts versus launchd
• mounting filesystems
• loopback mounting
• sparse files
• basic filesystem implementation
• VFS abstraction

In addition to reading the notes, be sure to review the assigned readings! You will also need to know the material covered in Test 1.

Sample Questions

Note: these questions are more open-ended than the ones that will be on the final test. There will also be a question session just before the test - the test will only be around 30 minutes long.

1. Without errors, what does the execve system call return?
2. Can a process modify its argument variables? Environment variables?
3. Who calls a signal handler?
4. If a parent and child process start printing "Parent\n" and "Child\n" to standard out, what will be the order of the output?
5. In race-demo, why does the consumer sometimes finish before the producer has done hardly anything?
6. What does pthread_join() do?
7. How is argc calculated? Note that argc is not specified by execve!
8. What parts of the kernel would you need to re-implement in userspace in order to simulate a loopback mount?
9. Why are sparse files tricky to copy?
10. what is the relationship between lost+found and fsck?