Extremely high cpu usage when using nix-shell with cuPy

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1

I’ve been trying to replace the processing backend of numpy with cuPy to accelerate my project. When I try to enter the shell.nix after adding cuPy as a package, my CPU usage maxes out at 100% (Intel® Core™ i7-14650HX × 24) during the compiling process. After a while, all applications including the terminal crashes. I’ve faced the same issue with the pytorch package before as well. (This issue seems to be present in other python packages with gpu acceleration functionality, might be because I’m using an nvidia GPU) You can see the shell.nix file below:

{ pkgs ? import <nixpkgs> {} }:
pkgs.mkShell {
  name = "python-env";
  buildInputs = with pkgs.python312Packages; [
    pkgs.python312
    numpy
    cupy
    pandas
    matplotlib
    scikit-learn

    venvShellHook
  ];
  venvDir = "venv";
  src = null;
}
2

It does look like cuPy runs on the integrated GPU (Intel) instead of your dedicated GPU (Nvidia).

hardware acceleration needs to be enabled / set for the Nvidia GPU.
Maybe have a look at that post: Nvidia open breaks hardware acceleration - #3 by TLATER

You prolly can try to run nvidia-smi when running your python project to check if it’s running on the Nvidia GPU and confirm your issue.

3

Cuda is unfortunately completely unrelated to vaapi (in fact the nvidia-vaapi-driver needs cuda to function), so nothing in that thread will help here.

1 Like
4

Indeed, it seems like nix is trying to build the cupy packages on a device other than my dGPU. However, I’ve been trying to build the package in discrete graphics mode (iGPU isn’t recognized) to begin with, so it would seem that nix doesn’t recognize the dGPU. Here’s the output for nvidia-smi during the build process:

+-----------------------------------------------------------------------------------------+
| NVIDIA-SMI 570.124.04             Driver Version: 570.124.04     CUDA Version: 12.8     |
|-----------------------------------------+------------------------+----------------------+
| GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
| Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
|                                         |                        |               MIG M. |
|=========================================+========================+======================|
|   0  NVIDIA GeForce RTX 4060 ...    Off |   00000000:01:00.0  On |                  N/A |
| N/A   44C    P4             13W /   55W |    1371MiB /   8188MiB |      0%      Default |
|                                         |                        |                  N/A |
+-----------------------------------------+------------------------+----------------------+

+-----------------------------------------------------------------------------------------+
| Processes:                                                                              |
|  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
|        ID   ID                                                               Usage      |
|=========================================================================================|
|    0   N/A  N/A            9278      G   ...me-shell-47.4/bin/gnome-shell        785MiB |
|    0   N/A  N/A            9726      G   ...-xwayland-24.1.6/bin/Xwayland          2MiB |
|    0   N/A  N/A           10197      G   ...r-user/nodev/bin/zen-twilight        285MiB |
|    0   N/A  N/A           11673      G   ...Ptr --variations-seed-version         91MiB |
|    0   N/A  N/A           41133      G   .../per-user/nodev/bin/alacritty         24MiB |
|    0   N/A  N/A           43902      G   .../per-user/nodev/bin/alacritty         24MiB |
+-----------------------------------------------------------------------------------------+

I’m unsure about how I can make nix-shell recognize the dGPU though. Is there any specific environment variable that needs to be explicitly set beforehand?

5

To be sure, are you using Nixos or Nix?

If Nixos, could you share your configuration.nix?