Data-parallelism on CUDA using Transducers.jl and for loops (FLoops.jl)
Author JuliaFolds
26 Stars
Updated Last
2 Years Ago
Started In
October 2020


Dev Buildkite status Run tests w/o GPU

FoldsCUDA.jl provides Transducers.jl-compatible fold (reduce) implemented using CUDA.jl. This brings the transducers and reducing function combinators implemented in Transducers.jl to GPU. Furthermore, using FLoops.jl, you can write parallel for loops that run on GPU.


FoldsCUDA exports CUDAEx, a parallel loop executor. It can be used with the parallel for loop created with FLoops.@floop, Base-like high-level parallel API in Folds.jl, and extensible transducers provided by Transducers.jl.


findmax using FLoops.jl

You can pass CUDA executor FoldsCUDA.CUDAEx() to @floop to run a parallel for loop on GPU:

julia> using FoldsCUDA, CUDA, FLoops

julia> using GPUArrays: @allowscalar

julia> xs = CUDA.rand(10^8);

julia> @allowscalar xs[100] = 2;

julia> @allowscalar xs[200] = 2;

julia> @floop CUDAEx() for (x, i) in zip(xs, eachindex(xs))
           @reduce() do (imax = -1; i), (xmax = -Inf32; x)
               if xmax < x
                   xmax = x
                   imax = i

julia> xmax

julia> imax  # the *first* position for the largest value

extrema using Transducers.TeeRF

julia> using Transducers, Folds

julia> @allowscalar xs[300] = -0.5;

julia> Folds.reduce(TeeRF(min, max), xs, CUDAEx())
(-0.5f0, 2.0f0)

julia> Folds.reduce(TeeRF(min, max), (2x for x in xs), CUDAEx())  # iterator comprehension works
(-1.0f0, 4.0f0)

julia> Folds.reduce(TeeRF(min, max), Map(x -> 2x)(xs), CUDAEx())  # equivalent, using a transducer
(-1.0f0, 4.0f0)

More examples

For more examples, see the examples section in the documentation.

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