1. Lab Project #4: PerfLab— Code Optimizations and Performance
Professor Hugh C. Lauer CS-2011, Machine Organization and Assembly Language
(Slides include copyright materials from Computer Systems: A Programmer’s Perspective, by Bryant and O’Hallaron, and from The C Programming Language, by Kernighan and Ritchie)
CS-2011, D-Term 2013
Lab Project #4: PerfLab

2. Objective and Approach
To gain a deeper understanding of how the performance of compiled code is affected by the way you handle the data …
… by modifying two image processing routines
I.e., rotate() and smooth()
CS-2011, D-Term 2013
Lab Project #4: PerfLab

3. We will build and run your submission using driver
Obtaining Perflab
See handout on course website
Click on “Lab Projects,” log in with your WPI user name and password
Click on perflab-handout.tar to download
You will get a tar file containing source code and makefile to build this project:–
kernels.c — the place where you will write your code
driver — the primary target of the makefile. Use this to run your code and get performance measurements
We will build and run your submission using driver
Other stuff — necessary to build and run
CS-2011, D-Term 2013
Lab Project #4: PerfLab

4. This Project Two functions to experiment with — rotate() and smooth()
For each one, you must:–
Write or modify some C code to traverse two image arrays most efficiently
Run them in the driver to get a performance measurement and a comparison against a baseline
Challenge:–
To achieve the greatest speedup
CS-2011, D-Term 2013
Lab Project #4: PerfLab

5. Background and resources
Anything we have learned about IA32 Assembly
Anything we have learned about caches and caching
Stuff from Chapter 5 that we have not covered in class
E.g., code motion, loop unrolling, blocking
Substituting adds for multiplies, etc.
Maximum gcc optimization levels
Anything else you can find
CS-2011, D-Term 2013
Lab Project #4: PerfLab

6. Working on Perflab Individually or two-person teams
Entirely in C source code
However, you may use your knowledge of IA32 Assembly
May be done on any Linux system
Possibly also on Macintosh systems
Unfortunately, not on Windows with Eclipse
Submission:–
A single file kernels.c
Due date:–April 28, 2013, 11:59 PM
CS-2011, D-Term 2013
Lab Project #4: PerfLab

7. Submit via Turnin Naming your file
<userID>-kernels.c for an individual
<userID1>-<userID2>-kernels.c for a team
Edit team_t team structure in kernels.c
Insert names and addresses of team members
Will be recognized by autograding system
This is called Perflab in Turnin system
CS-2011, D-Term 2013
Lab Project #4: PerfLab

8. Questions?
CS-2011, D-Term 2013
Lab Project #4: PerfLab