https://github.com/sbstndb/nbody_k

A simple 3D naïve NBody simulation using Kokkos enabling CUDA or OpenMP backend
https://github.com/sbstndb/nbody_k

cuda kokkos nbody openmp simulation

Last synced: 21 days ago
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A simple 3D naïve NBody simulation using Kokkos enabling CUDA or OpenMP backend

• Host: GitHub
• URL: https://github.com/sbstndb/nbody_k
• Owner: sbstndb
• Created: 2024-08-09T19:55:13.000Z (6 months ago)
• Default Branch: main
• Last Pushed: 2024-08-10T22:03:08.000Z (6 months ago)
• Last Synced: 2024-11-23T00:28:53.267Z (3 months ago)
• Topics: cuda, kokkos, nbody, openmp, simulation
• Language: C++
• Homepage:
• Size: 23.4 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Introduction

Here is a simple NBody simulator. It uses a naive algorithm - in a O(n²) complexity. 

The aim of this project is to have a first look at the Kokkos library.

From the [Kokkos](https://github.com/kokkos) github repo : 

> The Kokkos C++ Performance Portability Ecosystem is a production level solution for writing modern C++ applications in a hardware agnostic way.

Thanks to Kokkos, you can compile this code for multiple backends like OpenMP, CUDA, HIP. 

**Disclaimer:** Please note that this project is a work in progress and may contain errors or programming oversights due to its experimental nature. Your understanding and feedback are appreciated as we continue to develop and refine this code.

# Prerequisites

The code use Kokkos as a performance portability library. Then, you must have it to compile the project.

I suggest you to install it and read the documentation for further understanding. 

# Compilation

Compile the code by specifying your kokkos install directory with the following commands : 

```

cmake -B build -S . -DKokkos_ROOT=/usr/local/lib64/cmake/Kokkos

cmake --build build/

```

I Suggest you to read the Kokkos documentation if you want to compile with a specific backend. 

# Usage

You can currently launch the SOA version named `NBody_SOA` with :

```

./build/NBody_3D -N 10240 -nrepeat 100 -f 100 -d 0.001

```

With the following arguments : 

- `-n` particles

- `-nrepeat` iterations

- `d` timestep

- `f` frames - each frame consume `nrepeat` iterations and save the values in the `frames` directory

# Todo 

### To-Do List

- [ ] Refactoring

- [ ] Hierarchical parallelism with Kokkos

- [ ] Shared memory kernels with scratch pads

- [ ] Kokkos::SIMD usage

- [ ] Barnes-Hut implementation

- [ ] Fast Multipole Method (FMM) implementation

- [ ] Add periodic boundary conditions

- [ ] Python animation generator

- [x] Set up the CMake build system

- [x] Test the code on different backends (CUDA, OpenMP, Serial)