15-347/18-347 Spring '98
Notes on Assignments and Exams

Final Exam

• Get your own postscript copy of the exam as a memento of the course.
• Better yet, here is the official solution.

A review session will be held in Wean Hall 7500 on Sunday evening, May 10, starting at 7:00 pm.

As usual, the exam will be open book, open notes, etc. All answers will be written on the exam sheets. You may bring calculators.

All material will be covered. Particular emphasis will be on:

• Things we've covered since Exam 2. This includes pipelining, exceptions, superscalar processors, multimedia computing, networking, and multiprocessing. The depth of coverage will be greater for things you've encountered in labs and homeworks vs. things you've just heard lectures about.
• Things that caused problems on Exams 1 and 2. This includes things like caches, and machine-level data structures and referencing.
• Things that combine different themes of the course, e.g., I/O bandwidth requirements for multimedia applications.

Copies of old exams and (in some cases) their solutions are available. These old exams have somewhat different coverage than our course, so don't use them as your sole means of studying.

• Exam #1, Spring '96 Postscript
• Exam #2, Spring '96 Postscript
• Final Exam, Spring '96 Postscript
• Exam #1, Spring '97 Postscript, Solution
• Exam #2, Spring '97 Postscript Solution
• Final Exam, Spring '97 Postscript Solution

Homework 4

Unlike other assignments this term, you must work on this one individually. The problems are similar to ones that have appeared on past exams. They should serve as useful practice for the final exam.

Clarifications & Corrections:

• The hard copy version handed out in class had some incorrect entries for the TLB table (page 1), and the cache table (page 2). None affected the answers to the problems. The online version has been corrected.
• The assignment does not explicitly state whether the cache is virtually or physically addressed. But, there's enough information present to determine which form is used.

Lab 3

Part I (Prologue)

• Writeup for Prologue:
  • Gigantic Postscript file that will probably break your printer.
  • More reasonable Adobe Acrobat file.
• Formatted solution sheets in Postscript format. You will fill these in by hand and turn them in.

You will be using two version of the simulator in the directory AFS740/sim. Here are some considerations in using these programs:

• You must run these on one of the class alpha machines.
• You must telnet from a host that supports the X11 interface.
• You must be connected to the program directory while running the programs
• The two program examples, along with the example programs shown in class, are available in the demos subdirectory.
• For example, you can run the good simulator on the first program by connecting to the simulator directory and giving the command:
  ./solve_tk demos/pipe1.O &

Part II

• By 3pm Thursday, April 16, you should make an electronic handin of your stages.c code using the handin procedure described in the lab writeup. We will run our tests on your code and give you diagnostics on how well your code does. The correctness of this initial solution will count 10% of your overall lab grade. The more significant incentive is that it will give you a chance to fix your code for the final handin.
• By 3pm Thursday, April 23, you should make the final handin, both electronic and hardcopy. Follow the instructions in the Lab writeup. Hand in a new electronic version even if your code is the same as your earlier version.

An electronic version of the lab description is available in postscript. Note that there is both electronic and hard-copy submissions for this lab.

Exam 2

Covered material included topics up through Lecture #16 of March 10 (not March 17 as originally posted), as well as the instruction encoding coverage of Lecture #17 of March 12. The main coverage was on Alpha assembly-level programming and the relationship between C code and the machine code by a C compiler. Some things particularly to review include:

• Alpha instructions and assembly code
• Stack frames, register usage
• Structure, union, and array allocations including alignment constraints
• Pointer computations, array indexing, memory referencing
• Why compilers having trouble optimizing some types of code
• Encoding & decoding Alpha instructions.

• Exam #1 (Postscript exam, Text solution), Problems 1, 3, 4, 8
• Final (Postscript exam, Text solution), Problems 4, 12

Lab 2

Homework 3

The files you need for this assignment are in the directory HOME347/asst/h3.

The extra credit portion of this assignment will be worth 25% of the total weight for this assignment.

NOTE: gcc generates some floating point loads and stores in the compiled version of swapC for the following (obscure) reason: the Alpha 21164 can issue two memory operations simultaneously only if one is an integer load/store and the other is a float point load/store. Hence this is a machine-specific performance optimization. You do not need to worry about this issue in your writeup of the assignment.

NOTE: gcc also has some problems compiling code that uses the include file sys/time.h, such as the file etime.c from Asst 1. Here are two workarounds:

• Use cc instead of gcc. The generated assembly code is a little harder to read, but it's not too bad. In fact cc generally produces more efficient code.
• Include the options -nostdinc -I/usr/include on the command line for gcc. That forces gcc to use the same include files as does cc.

Exam 1

Lab 1

This lab requires use of the dinero cache simulator from Wisconsin. Compiled versions of the code for various CPU types is available in the directory HOME347/labs/lab1/dinero/bin. If you don't like any of the choices there, you can get a copy of the source code and compile it yourself. The code is in the archive file HOME347/labs/lab1/dinero.tar.

You'll want to use scripting languages to automate the running of the experiments and the extraction of the results. Check out the scripts block.csh and block.pl in the directory HOME347/scripts/.

The trace files you'll be using are in the directory HOME347/trace-files/. You should make symbolic links to them rather than making copies, since they are quite large.

Here is a postscript version of the solutions.

Homework 2

The files you need for this assignment are in the directory HOME347/asst/h2.

If you know LaTeX and want to generate your solution by modifying the assignment write-up, you can retrieve the files h2.tex and prob.sty from the assignment directory.

Here is a postscript version of the solutions. The C code for the arithmetic functions is available in the file solve-numbers.c.

Homework 1

The files for this assignment are in the directory HOME347/asst/h1.