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An Embedded Language for Accelerated Array Computations

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Data.Array.Accelerate defines an embedded language of array computations for high-performance computing in Haskell. Computations on multi-dimensional, regular arrays are expressed in the form of parameterised collective operations (such as maps, reductions, and permutations). These computations are online-compiled and executed on a range of architectures.

For more details, see our papers:

There are also slides from some fairly recent presentations:

Chapter 6 of Simon Marlow's book Parallel and Concurrent Programming in Haskell contains a tutorial introduction to Accelerate.

Trevor's PhD thesis details the design and implementation of frontend optimisations and CUDA backend.

Table of Contents

A simple example

As a simple example, consider the computation of a dot product of two vectors of single-precision floating-point numbers:

dotp :: Acc (Vector Float) -> Acc (Vector Float) -> Acc (Scalar Float)
dotp xs ys = fold (+) 0 (zipWith (*) xs ys)

Except for the type, this code is almost the same as the corresponding Haskell code on lists of floats. The types indicate that the computation may be online-compiled for performance — for example, using Data.Array.Accelerate.CUDA.run it may be on-the-fly off-loaded to a GPU.

Availability

Package accelerate is available from

  • Hackage: accelerate — install with cabal install accelerate
  • GitHub: AccelerateHS/accelerate - get the source with git clone https://github.com/AccelerateHS/accelerate.git

Additional components

The following supported addons are available as separate packages on Hackage and included as submodules in the GitHub repository:

  • accelerate-cuda Backend targeting CUDA-enabled NVIDA GPUs — requires the NVIDIA CUDA SDK and hardware with compute capability 1.2 or greater (see the table on Wikipedia)
  • accelerate-examples Computational kernels and applications showcasing the use of Accelerate as well as a regression test suite (supporting function and performance testing)
  • accelerate-io Fast conversion between Accelerate arrays and other array formats (including Repa arrays)
  • accelerate-fft Fast Fourier transform implementation, with optimised implementation for the CUDA backend
  • accelerate-backend-kit Simplified internal AST to get going on writing backends
  • accelerate-buildbot Build bot for automatic performance & regression testing

Install them from Hackage with cabal install PACKAGENAME.

The following components are experimental and incomplete incomplete:

  • accelerate-llvm A framework for constructing backends targeting LLVM IR, with concrete backends for multicore CPUs and NVIDIA GPUs.

The following components are incomplete and not currently maintained. Please contact us if you are interested in working on them!

Requirements

  • Glasgow Haskell Compiler (GHC), 7.8.3 or later
  • For the CUDA backend, CUDA version 5.0 or later
  • Haskell libraries as specified in the accelerate.cabal and optionally accelerate-cuda.cabal files.

Documentation

  • Haddock documentation is included in the package and linked from the Hackage page.
  • Online documentation is on the GitHub wiki.
  • The idea behind the HOAS (higher-order abstract syntax) to de-Bruijn conversion used in the library is described separately.

Examples

The GitHub repository contains a submodule accelerate-examples, which provides a range of computational kernels and a few complete applications. To install these from Hackage, issue cabal install accelerate-examples. The examples include:

  • An implementation of canny edge detection
  • An interactive mandelbrot set generator
  • An N-body simulation of gravitational attraction between solid particles
  • An implementation of the PageRank algorithm
  • A simple ray-tracer
  • A particle based simulation of stable fluid flows
  • A cellular automata simulation
  • A "password recovery" tool, for dictionary lookup of MD5 hashes

Mandelbrot Raytracer

Accelerate users have also built some substantial applications of their own. Please feel free to add your own examples!

  • Henning Thielemann, patch-image: Combine a collage of overlapping images
  • apunktbau, bildpunkt: A ray-marching distance field renderer
  • klarh, hasdy: Molecular dynamics in Haskell using Accelerate
  • Alexandros Gremm used Accelerate as part of the 2014 CSCS summer school (code)

Mailing list and contacts

The maintainers of Accelerate are Manuel M T Chakravarty [email protected] and Trevor L McDonell [email protected].

Citing Accelerate

If you use Accelerate for academic research, you are encouraged (though not required) to cite the following papers (BibTeX):

  • Manuel M. T. Chakravarty, Gabriele Keller, Sean Lee, Trevor L. McDonell, and Vinod Grover. Accelerating Haskell Array Codes with Multicore GPUs. In DAMP '11: Declarative Aspects of Multicore Programming, ACM, 2011.

  • Trevor L. McDonell, Manuel M. T. Chakravarty, Gabriele Keller, and Ben Lippmeier. Optimising Purely Functional GPU Programs. In ICFP '13: The 18th ACM SIGPLAN International Conference on Functional Programming, ACM, 2013.

  • Robert Clifton-Everest, Trevor L. McDonell, Manuel M. T. Chakravarty, and Gabriele Keller. Embedding Foreign Code. In PADL '14: The 16th International Symposium on Practical Aspects of Declarative Languages, Springer-Verlag, LNCS, 2014.

Accelerate is primarily developed by academics, so citations matter a lot to us. As an added benefit, you increase Accelerate's exposure and potential user (and developer!) base, which is a benefit to all users of Accelerate. Thanks in advance!

What's missing?

Here is a list of features that are currently missing:

  • Preliminary API (parts of the API may still change in subsequent releases)

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