Troubleshooting

Our PyTorch code uses custom CUDA extensions to speed up some of the network layers. Getting these to run can sometimes be a hassle.

This page aims to give guidance on how to diagnose and fix run-time problems related to these extensions.

Before you start

Try Docker first! Ensure you can successfully run our models using the recommended Docker image. Follow the instructions in README.md to get it running.
Can't use Docker? Read on..

Installing dependencies

Make sure you've installed everything listed on the requirements section in the README.md. The key components w.r.t. custom extensions are:

CUDA toolkit 11.1 or later (this is not the same as cudatoolkit from Conda).
- PyTorch invokes nvcc to compile our CUDA kernels.
ninja
- PyTorch uses Ninja as its build system.
GCC (Linux) or Visual Studio (Windows)
- GCC 7.x or later is required. Earlier versions such as GCC 6.3 are known not to work.

Why is CUDA toolkit installation necessary?

The PyTorch package contains the required CUDA toolkit libraries needed to run PyTorch, so why is a separate CUDA toolkit installation required? Our models use custom CUDA kernels to implement operations such as efficient resampling of 2D images. PyTorch code invokes the CUDA compiler at run-time to compile these kernels on first-use. The tools and libraries required for this compilation are not bundled in PyTorch and thus a host CUDA toolkit installation is required.

Things to try

Completely remove: $HOME/.cache/torch_extensions (Linux) or C:\Users\<username>\AppData\Local\torch_extensions\torch_extensions\Cache (Windows) and re-run StyleGAN3 python code.
Run ninja in $HOME/.cache/torch_extensions to see that it builds.
Inspect the build.ninja in the build directories under $HOME/.cache/torch_extensions and check CUDA tools and versions are consistent with what you intended to use.

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