From 1256ff450875f7eb82ea62ef0fbdf6ea9d9bc2e9 Mon Sep 17 00:00:00 2001 From: Lanre Shittu <136805224+Shizoqua@users.noreply.github.com> Date: Mon, 6 Jul 2026 20:40:34 +0100 Subject: [PATCH] Clarify CUDA/CuPy install requirements in docs (#8106) Signed-off-by: Shizoqua --- docs/source/installation.md | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/docs/source/installation.md b/docs/source/installation.md index 2d9e2a7f0e..ea4ec4058c 100644 --- a/docs/source/installation.md +++ b/docs/source/installation.md @@ -4,6 +4,7 @@ - [Installation Guide](#installation-guide) - [Table of Contents](#table-of-contents) + - [GPU-enabled installation (CUDA and CuPy)](#gpu-enabled-installation-cuda-and-cupy) - [From PyPI](#from-pypi) - [Milestone release](#milestone-release) - [Weekly preview release](#weekly-preview-release) @@ -30,12 +31,33 @@ Ignite](https://pytorch.org/ignite/), please follow the instructions: - [Installing the recommended dependencies](#installing-the-recommended-dependencies) -The installation commands below usually end up installing CPU variant of PyTorch. To install GPU-enabled PyTorch: +--- + +## GPU-enabled installation (CUDA and CuPy) + +The installation commands below usually end up installing the CPU variant of PyTorch. To install GPU-enabled PyTorch: 1. Install the latest NVIDIA driver. 1. Check [PyTorch Official Guide](https://pytorch.org/get-started/locally/) for the recommended CUDA versions. For Pip package, the user needs to download the CUDA manually, install it on the system, and ensure CUDA_PATH is set properly. 1. Continue to follow the guide and install PyTorch. -1. Install MONAI using one the ways described below. +1. Install MONAI using one of the ways described below. + +Installing GPU-enabled PyTorch is enough to run models and transforms on the GPU. Some transforms, +however, additionally use [CuPy](https://cupy.dev/) for GPU-accelerated array operations (for example +when a transform converts a CUDA tensor via `convert_to_cupy`). If CuPy is not installed, these code +paths raise `OptionalImportError: import cupy (No module named 'cupy')`. + +CuPy is provided through the `cucim` extra, so installing MONAI with that extra pulls in a compatible +CuPy build: + +```bash +pip install 'monai[cucim]' +``` + +If you prefer to install CuPy directly, note that the PyPI package name is CUDA-version specific +(e.g. `cupy-cuda12x` for CUDA 12.x, `cupy-cuda11x` for CUDA 11.x) rather than plain `cupy`. See the +[CuPy installation guide](https://docs.cupy.dev/en/stable/install.html) for the correct package for +your CUDA toolkit. --- @@ -298,3 +320,6 @@ O(N log N) alternatives to windowed self-attention). Install with `pip install 'monai[hyena]'`. - `pip install 'monai[all]'` installs all the optional dependencies. +- The `cucim` extra also provides [CuPy](https://cupy.dev/), which is required by GPU-accelerated + transforms. See [GPU-enabled installation (CUDA and CuPy)](#gpu-enabled-installation-cuda-and-cupy) + for details.