CS 3733 Operating Systems, Fall 1999 Assignment 2

Warning: This is not for the current semester.

Parts 0 and 1 Due Tuesday, October 5, 1999
Parts 2 and 3 Due Tuesday, October 19, 1999

In this assignment you will explore the topic of CPU scheduling by using the scheduling simulator described in class. You can find out more about the simulator at the web site: /nsf/process_scheduling.html.
A copy of the simulator user's guide can be found at /nsf/ps_doc/psdoc.html.
These links are also available from the course web page.

You might want to read about the experiences students had with the simulator in a previous semester in a paper available at /nsf/pubs/process.html.

Part 0

In this part you will run the simulator remotely and create a remote log file.

Look for the link Run the simulator remotely with log placed on vip on the course web page. Use this link to run the simulator.

Click on the Open Log button. You will be prompted to enter your username. Enter the name you use to log into our Sun network.

Click Open Log again and the button should change to Close Log.

Click on Run Experiment and then Log All Table Data.

Click on Draw Graph and then the Log button on the graph. It may take a few seconds while the graph is converted into a GIF and then sent over the network.

Click on Draw Gantt Chart and choose the first one.

Adjust the size so that the entire chart is shown. You can use the Controls to change the height of the bars.

Click on the Log button on the Gantt chart.

Do the smae for the second Gantt chart.

Close the log file and then click on Show Remote Log.

If all went well, the log file should pop up in a new browser window.

Print out the log file and hand it in.

Part 1

If you have not already done so, create a web page for yourself.
The address of your web page should be http://www.cs.utsa.edu/~username. Create a course web page with web address http://www.cs.utsa.edu/~username/cs3733/index.html. This should be globally accessible. Your course web page should be very simple without much graphics so that it will load quickly over a phone line.

Make a cs3733/assign2/part1, directory under your public_html directory. The permissions of the public_html, cs3733, assign2, and part1 directories should be drwxr-xr-x.

Make a directory somewhere in your account for this assignment called assign2. Do not put this under public_html. The permissions of this directory should be set so that only you have access to it. Make a subdirectory called part1. Copy all of the files from /usr/local/courses/java/psfiles/ into your part1 directory. Edit the psconfig file and change my name to yours. Make sure that your path includes /usr/local/courses/java/bin. Run the simulator using runps which is a script in this directory. This will run the simulator using Java 2. A few of the machines in the lab will not run Java 2. If you find a machine that will not, send me a mail message about which machine it is. You can use runps1 on these machines instead.

Run the simulator in the same way you did for Part 0. This will create a log file in your part1 directory along with three GIF files.

Copy these files into your assign2/part1 directory under you public_html. Set the permissions so that they are all world readable. Put a link to the log file in your course web page. Make sure you (and others) can access this log file through your link. Print out the log file and turn it in.

When you have completed Parts 0 and 1 of this assignment, send me email with the subject CS 3733 Assignment 2, Parts 0 and 1 complete.

Part 2

Consider 100 processes all arriving at the same time. They all have the same duration of 1000 units and constant I/O bursts of 5000 units. CPU burst times are uniformly distributed between 1 and 100. Do an experiment comparing FCFS and SJF for these processes. Concentrate on comparing average waiting time. Create an HTML log containing tables of statistics, graphs, and Gantt charts.

Also include in the HTML log file an analysis of the results. What do you conclude from this? Is the result what you would have predicted? Why did it turn out the way it did?

Estimate the load average for each of the runs. The load average is defined as the average number of processes in the ready queue. This information is not directly availble from the simulation statistics, but can be calcualted as the total waiting time divided by the time for the experiment.

Turn in a printout of your log file.

Part 3

Design an experiment which will test the following hypothesis: Create processes that have both short and long CPU burst times. Do all of your runs using the same sets of processes. Try to choose parameters so that the load average is between .5 and 2 for both FCFS and SJF and the average waiting time for these two algorithms is as different as possible. You may have to experiment with parameters to make this occur. I/O burst times should be considerably longer than CPU burst times.

Include tables, graphs and Gantt charts where appropriate and write up your results in the HTML log file created by the simulator. Print out and hand in the log file.

Be prepared to move the log files and associated GIF files for Parts 2 and 3 to a place accessible from your course web page. Do not move them yet.

If you have a machine at home with Java installed, you can run the simualtor at home by downloading the simulator code. Click here for more details.