Description
x Use gcc and gprof to profile a C program͛s performance͘
x Use Doxygen to document a C program.
Requirements
You are given two starter code files dotprod.zip and course.zip in the Assignment #9 folder in
the Avenue to Learn course shell.
Part A – Profiling Code
When you unzip dotprod.zip you will find a C program that conducts a dot product operation 1
billion times using a standard dot product algorithm. Improving the performance of linear
algebra operations such as dot product is actually very important in computer graphics (e.g.
video games) as operations like these are executed many times per second to generate
individual frames of animation.
Use gcc and gprof on the pascal server to profile the performance of the current program. Save
the results provided by gprof to a file called old_prof.txt.
Improve the performance of the program by creating and using a new dot product function in
place of the old dot product function. Right now the dot product function is implemented to
carry out the general dot product operation for vectors of a given length, and it uses a loop to
manage the number of calculations. This adds overhead to the function͛s execution, and that
overhead would be unnecessary if we only have dot products of vectors of length 3 (which
would not be unusual in a 3D game with coordinates x,y,z for example).
Create a function which assumes the vectors are both length 3. And then use the technique of
loop unrolling (see: https://en.wikipedia.org/wiki/Loop_unrolling#Early_complexity) to remove
the loop entirely. So your new function should consist of a single return statement that carries
out the dot product computation for vectors of length 3.
Use gcc and gprof on the pascal server to profile the performance of the new program. The
intention is that the new program is the same as the old program except using a new dot
product function you have creates instead. That said, if you do something like call both the old
and new functions in the loop conducting the dot product operation, or if you copy and paste
the loop testing the dot product function and have the 2nd loop test your version of the dot
product function, these would both be acceptable ways to test the function too. Save the
results provided by gprof to a file called new_prof.txt.
Save the new C program as dotprod.c. Zip the dotprod.c, old_prof.txt and new_prof.txt files
together into a file called dotprod.zip.
Part B – Using Doxygen
When you unzip course.zip you will find a C program with libraries for creating courses with
students. The main.c file is used to demonstrate these libraries.
Document this code using Doxygen comments. Be sure to document all files, functions
(parameters, return values), and typedef struct definitions.
Add additional regular comments to the function bodies where appropriate to make the code
easier to read. As discussed in-class, not every line should be commented, but brief descriptive
comments documenting what a section of code is doing (e.g. a loop) or interesting features
(e.g. why are both calloc and realloc being used in a function) is important.
Generate the Doxygen html documentation. Zip both your modified files and the Doxygen html
documentation in a file called course.zip.
Submission
As noted above, save your solution files in zip files called dotprod.zip and course.zip and submit
them to the Assignment #9 dropbox on Avenue to Learn.
Marking scheme
Component Description Marks
Profiling Before and after profiling results are provided with
expected value.
20
Optimization Optimized version of dot product function. 20
Doxygen Doxyen is used to comment the course program in the
expected ways.
40
Comments Regular comments are added to the function bodies of
the program as appropriate.
20
Total: 100
