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pySDC using GPUs¶

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Installation¶

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In order to start playing on GPU, install pySDC and its dependencies, ideally in developer mode. +First start by setting up a virtual environment, e.g. by using [Miniconda](https://docs.conda.io/en/latest/miniconda.html). +Then also add the CuPy Package (the cuda-toolkit will be installed automatically):

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conda create -n pySDC +conda activate pySDC +conda install -c conda-forge –file requirements.txt +conda install -c conda-forge cupy

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When this is done (and it can take a while), you have your setup to run pySDC on the GPU.

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Changes in the problem_classes¶

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Now you have to change a little bit in the problem_classes. The first and easy step is to change the datatype. +To use pySDC on the GPU with CuPy you must use the [cupy-datatype](../../implementations/datatype_classes/cupy_mesh.py). +The next step is to import cupy in the problem_class. In the following you have to exchange the NumPy/SciPy functions with the CuPy functions. +A [Comparison Table](https://docs.cupy.dev/en/latest/reference/comparison.html) is given from CuPy to do that. +For example: The above steps can be traced using the files +[HeatEquation_ND_FD_forced_periodic.py](../../implementations/problem_classes/HeatEquation_ND_FD_forced_periodic.py) +and [HeatEquation_ND_FD_forced_periodic_gpu.py](../../implementations/problem_classes/HeatEquation_ND_FD_forced_periodic.py) +Now you are ready to run pySDC on the GPU.

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Run pySDC on the GPU¶

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You have to configure a script to run it. You can see at the file [heat.py](heat.py) that the parameters are the +same for GPU and CPU. Only the import for the problem_class changed.

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More examples¶

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Further examples can found with Allen-Cahn: +* problem: [AllenCahn_2D_FD.py](../../implementations/problem_classes/AllenCahn_2D_FD.py) and [AllenCahn_2D_FD_gpu.py](../../implementations/problem_classes/AllenCahn_2D_FD_gpu.py) +* problem: [AllenCahn_2D_FFT.py](../../implementations/problem_classes/AllenCahn_2D_FFT.py) and [AllenCahn_2D_FFT_gpu.py](../../implementations/problem_classes/AllenCahn_2D_FFT_gpu.py)

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  • Script to run pySDC: [ac-fft.py](ac-fft.py)

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Running large problems on GPU¶

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This project contains some infrastructure for running and plotting specific problems. +The main file is run_experiment and can be configured using command line arguments. +For instance, use

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srun -n 4 python work_precision.py --config=GS_USkate --procs=1/1/4 --useGPU=True --mode=run
+mpirun -np 8 python work_precision.py --config=GS_USkate --procs=1/1/4 --useGPU=True --mode=plot
+python work_precision.py --config=GS_USkate --procs=1/1/4 --useGPU=True --mode=video
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to first run the problem, then make plots and then make a video for Gray-Scott with the U-Skate configuration (see arXiv:1501.01990).

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To do a parallel scaling test, you can go to JUWELS Booster and use, for instance,

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This will generate jobscripts and submit the jobs. Notice that you have to wait for the jobs to complete before you can plot them.

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To learn more about the options for the scripts, run them with –help.

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