CS 3733 Operating Systems, Spring 2005 Recitation Review

1. Week of January 24: Using the system
   In this recitation you learned how to compile programs on the Linux system and you write the get_filesize function.
2. Week of January 31: Timing and Static VariablesA
   In this recitation you experimented with the consequences of calling functions that use static variables.
3. Week of February 7: The Process Scheduling Simulator
   In this recitation you started using the simulator and got ready for Assignment 2.
4. Week of February 14: The Process Scheduling Simulator continued
   In this recitation you modified the simulator input to do 5 experiments.
   There were 10 processes with short CPU bursts and 10 with longer ones.
   The algorithms used were FCFS, SJF, RR 1, RR 5 and RR 10.
   You should have found that in this case SJF had the best average waiting time and FCFS was next. Increasing the quantum for the RR produced better average waiting times and if it were allowed to increase above the largest CPU burst it would be identical to FCFS.
5. Week of February 28: Threads
   In this recitation you learned how to compile and run threads under Linux and Solaris.
   Some of the things you should have experienced:
   6. Here you had a parent and child each calculating a value and adding it to a sum. Since each had its own sum variable, the value did not represent the sum of the values calculated. The program is here.
   7. Having the parent wait for the child to finish would not help here.
   8. When the same is done with two threads, the threads share the same sum variable so the sum represents the sum of the two values. The original process joins the thread before doing its calculation so there is no interference. The program is here.
   9. If the thread is not joined, what happens depends on how the original process and the thread are scheduled. You probably found that under Linux the program usually gave the correct answer.
   12. Under Linux, if the reference to -lpthread was removed, the program would not compile.
   15. When run under Solaris with the join commented out you probably found that most of the time the original process printed its results and exited before the thread had a chance to execute.
   16. When run under Solaris, the original program ran as expected.
   19. When you try to compile under Solaris without the -lpthread, the compile is successful but the program fails on the pthread_create.
6. Week of March 7: Ring Simulator Introduction
   In this recitation you started using the simulator.
7. Week of March 21: Ring Simulator
   In this recitation you continued using the simulator. You should have found the following:
   • For the original ring, the order of the output is not predictable.
   • The order may change depending on how the processes are scheduled.
   • If each parent waits for its child before printing, the statements come out in reverse order of process creation.
   • If printing is not atomic, messages get jumbled up.
8. Week of March 28: Bounded Buffer Simulator
   In this recitation you should have found that an internal inconsistency may occur long before its effect (the external inconsistency) is seen.
9. Week of April 4: Network Communication
   In this recitation you learned how to compile network programs under Linux. You experimented with multiple connections to the server and found that with multiple clients connecting to the same server, you cannot predict which client gets the messages typed at the server.
10. Week of April 11: Disk Head Simulator
    In this recitation you started using the simulator.