CS 3733 Operating Systems, Spring 2007 Recitation Review

1. Week of January 22: 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 29: Timing and Static Variables
   In this recitation you experimented with the consequences of calling functions that use static variables.
3. Week of February 5: The Process Scheduling Simulator
   In this recitation you started using the simulator and got ready for Assignment 2.
4. Week of February 12: 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 19: 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.

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