GPU acceleration seemingly not used in headless rendering with EGL

Hi,

I am running pyrender in a Docker container with nvidia runtime. (nvidia/cudagl:10.2-runtime-ubuntu18.04)

I can check that the GPU passthrough works by seeing the output of nvidia-smi.

Pyrender works fine with PYOPENGL_PLATFORM=egl, and I can produce the expected image. I know that Pyrender is at least checking the presence of the GPU because if I fail to enable the GPU in the container it exits with an error.

So - functionally it seems all fine.

However: I don’t think that the GPU is actually being used. When I run my program (which is producing a video using pyrender) I can see the CPU is pegged at 100% - while I would expect that the execution should be GPU bound. Moreover, the performance that I see is compatible with the speed of software rendering.

I did a deep dive into the code, trying to isolate where is the problem. I use flags = FLAT. I disabled the reading of the depth buffer (it took 40ms per frame), optimized to some extent the caching of the program, etc., until I had to realize that the bottleneck is the drawing (glDrawElementsInstanced). If I understand correctly, calling this should not be a CPU-bound operation, as the GPU will do most of the work.

So I’m thinking that somehow PyRender is not actually using the acceleration.

How can I debug this issue?

One question that I have is the following: where can I check that the renderer is actually a hardware rendererer? in platforms/ I didn’t see an obvious place where to get the name of the renderer.

I am using Python packages:

PyOpenGL (3.1.0)
PyOpenGL-accelerate (3.1.0)
pyrender (0.1.43, /project/pyrender)

Docker base image nvidia/cudagl:10.2-runtime-ubuntu18.04 plus APT packages libglfw3-dev libgles2-mesa-dev freeglut3-dev.

nvidia-smi from the container:

+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.100      Driver Version: 440.100      CUDA Version: 10.2     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce RTX 208...  Off  | 00000000:65:00.0  On |                  N/A |
| 35%   35C    P8    21W / 260W |    536MiB / 11018MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
+-----------------------------------------------------------------------------+