Using PyTorch on Berzelius

• Introduction
• Installing PyTorch via Conda/Mamba
• Installing PyTorch via pip
• Installing PyTorch via Apptainer
• Performance Optimization

Introduction

PyTorch is an open-source machine learning library for Python that provides a flexible and efficient framework for building and training deep neural networks. PyTorch is commonly used for various machine learning tasks, including deep learning, natural language processing (NLP), computer vision, reinforcement learning, and more.

You can install PyTorch on Berzelius using different ways, such as Conda/Mamba and pip, following PyTorch official installation instructions. You can also install and utilize PyTorch through Apptainer container.

Installing PyTorch via Conda/Mamba

It is a good practice to specify the version of the main package to install (PyTorch in this case).

module load Mambaforge/23.3.1-1-hpc1-bdist
mamba create --name pytorch_2.1.0
mamba activate pytorch_2.1.0
mamba install pytorch=2.1.0 torchvision torchaudio pytorch-cuda=11.8 -c pytorch -c nvidia

To check if PyTorch detects the GPU:

python -c "import torch; print('GPU available: ' + str(torch.cuda.is_available()))"

Installing PyTorch via pip

module load Mambaforge/23.3.1-1-hpc1-bdist
mamba create --name pytorch_2.1.0
mamba activate pytorch_2.1.0
pip3 install torch==2.1.0 torchvision torchaudio --index-url https://download.pytorch.org/whl/cu118

Installation instructions for old versions of PyTorch are provided here.

Installing PyTorch via Apptainer

We can build an Apptainer image using the following definition file pytorch_2.0.1.def. To learn more refer to the Apptainer User Guide.

Bootstrap: docker
From: nvidia/cuda:11.7.1-cudnn8-devel-ubuntu22.04

%environment

export PATH=/opt/mambaforge/bin:$PATH
export PYTHONNOUSERSITE=True

%post

apt-get update && apt-get install -y --no-install-recommends \
git \
nano \
wget \
curl

# Install Mambaforge
cd /tmp
curl -L -O "https://github.com/conda-forge/miniforge/releases/latest/download/Mambaforge-$(uname)-$(uname -m).sh"
bash Mambaforge-$(uname)-$(uname -m).sh -fp /opt/mambaforge -b
rm Mambaforge*sh

export PATH=/opt/mambaforge/bin:$PATH

mamba install python==3.10 pytorch==2.0.1 torchvision torchaudio torchdata torchtext pytorch-cuda=11.7 -c pytorch -c nvidia -y

# Pin packages
cat <<EOT > /opt/mambaforge/conda-meta/pinned
pytorch==2.0.1
EOT

mamba install matplotlib jupyterlab -y

We build the image from the definition file:

apptainer build pytorch_2.0.1 pytorch_2.0.1.def

The Apptainer image can be easily extended with more packages and software by modifying the definition file and rebuilding the image.

Performance Optimization

We expect jobs properly utilizing the GPUs on Berzelius. Particularly inefficient jobs will be automatically terminated. Please read Berzelius GPU Usage Efficiency Policy for more details.

There are many performance profilers and profiling tools that allow you to analyze the runtime behavior of your Python code, identify bottlenecks, and optimize performance.

One example workflow of code optimization is as follows.

1. Use line_profiler to identify the bottleneck.

2. Locate the most inefficient part of your code and optimize it.

3. Rerun the code.

Please read PyTorch Performance Tuning Guide for the possible optimizations which can accelerate training and inference of deep learning models in PyTorch.