04. [30p] GPU Monitoring
a. [0p] Clone Repository and Build Project
Clone the repository containing the tasks and change to this lab's task 04. Follow the instructions to install the dependencies and build the project from the README.md.
$ git clone https://github.com/cs-pub-ro/EP-labs.git $ cd EP-labs/lab_05/task_04
If you get a GLFW error from glfwCreateWindow(), the most likely cause is that the maximum OpenGL version supported on your system does not meet the minimum requirement for the application. Note however that this minimum required version of OpenGL 4.6 core was chosen arbitrarily and you can change it.
# note how the OpenGL core profile version is < 4.6 $ glxinfo | grep 'OpenGL core profile version' OpenGL core profile version string: 4.3 (Core Profile) Mesa 26.0.3-arch2.2
Modify the GLFW_CONTEXT_VERSION_MINOR window hint in main.cpp from 6 to 3 (or whatever you've got). Do the same for the major version if yours is way behind any normal standard.
Now the window will be created but the application will still crash during the shader compilation. Modify the first line in both the vertex and the fragment shader:
-#version 460 core +#version 430 core
b. [10p] Run Project and Collect Measurements
To run the project, simply run the binary generated by the build step. This will render a scene with a sphere. Follow the instructions in the terminal and progressively increase the number of vertices. Upon exiting the simulation with Esc, two .csv files will be created. You will use these measurements to generate plots.
Also pay close attention to your RAM!
Increase vertices until you have less than 10 FPS for good results.
c. [10p] Generate Plot
We want to interpret the results recorded. In order to do this, we need to visually see them in a suggestive way. Plot the results in such a way that they are suggestive and easy to understand.
- One single plot for all results
- Left OY axis shows FPS as a continuous variable
- Right OY axis shows time spent per event in ms
- OX axis follows the time of the simulation without any time ticks
- OX axis has ticks showing the number of vertices for each event that happens
- Every event marked with ticks on the OX axis has one stacked bar chart made of two components:
- a. a bottom component showing time spent copying buffers
- b. a top component showing the rest without the time spent on copying buffers
d. [10p] Interpret Results
Explain the results you have plotted. Answer the following questions:
- Why does the FPS plot look like downwards stairs upon increasing the number of vertices?
- Why does the FPS decrease more initially and the stabilizes itself at a higher value?
- What takes more to compute: generating the vertices, or copying them in the VRAM?
- What is the correlation between the number of vertices and the time to copy the Vertex Buffer?
- Why is the program less responsive on a lower number of frames?
e. [10p] Bonus Dedicated GPU
Go back to step b. and rerun the binary and make it run on your dedicated GPU. Redo the plot with the new measurements. You do not need to answer the questions again.
If you use AMD, you can use the DRI_PRIME=1 environment variable.
