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Switch DGMulti to Matrix{<:SVector} solution storage #1952

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Switch DGMulti to Matrix{<:SVector} solution storage #1952

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54f55e0
remove Octavian and matmul! (#1950)
jlchan May 23, 2024
d44f41a
bump StartUpDG compat to 1
jlchan May 23, 2024
c7b38bb
Merge branch 'main' into jc/dev_DGMulti
jlchan May 23, 2024
291f487
switch from StructArrays
jlchan May 23, 2024
a6170c6
Merge branch 'main' into jc/dev_DGMulti
jlchan May 24, 2024
99c9864
Merge branch 'main' into jc/dev_DGMulti
jlchan May 30, 2024
9a14f12
Merge branch 'main' into jc/dev_DGMulti
jlchan Jun 4, 2024
5bbf9e4
Merge branch 'main' into jc/dev_DGMulti
jlchan Sep 10, 2024
97c4c5d
Merge branch 'main' into jc/dev_DGMulti
jlchan Sep 15, 2024
c2fa8e9
Merge branch 'main' into jc/dev_DGMulti
jlchan Oct 14, 2024
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2 changes: 0 additions & 2 deletions Project.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@ LinearMaps = "7a12625a-238d-50fd-b39a-03d52299707e"
LoopVectorization = "bdcacae8-1622-11e9-2a5c-532679323890"
MPI = "da04e1cc-30fd-572f-bb4f-1f8673147195"
MuladdMacro = "46d2c3a1-f734-5fdb-9937-b9b9aeba4221"
Octavian = "6fd5a793-0b7e-452c-907f-f8bfe9c57db4"
OffsetArrays = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
P4est = "7d669430-f675-4ae7-b43e-fab78ec5a902"
Polyester = "f517fe37-dbe3-4b94-8317-1923a5111588"
Expand Down Expand Up @@ -82,7 +81,6 @@ LoopVectorization = "0.12.151"
MPI = "0.20"
Makie = "0.19, 0.20"
MuladdMacro = "0.2.2"
Octavian = "0.3.21"
OffsetArrays = "1.12"
P4est = "0.4.9"
Polyester = "0.7.10"
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1 change: 0 additions & 1 deletion src/Trixi.jl
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Expand Up @@ -53,7 +53,6 @@ using LinearMaps: LinearMap
using LoopVectorization: LoopVectorization, @turbo, indices
using StaticArrayInterface: static_length # used by LoopVectorization
using MuladdMacro: @muladd
using Octavian: Octavian, matmul!
using Polyester: Polyester, @batch # You know, the cheapest threads you can find...
using OffsetArrays: OffsetArray, OffsetVector
using P4est
Expand Down
15 changes: 8 additions & 7 deletions src/solvers/dgmulti/dg.jl
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Expand Up @@ -6,15 +6,15 @@
#! format: noindent

# out <- A*x
mul_by!(A) = @inline (out, x) -> matmul!(out, A, x)
mul_by!(A) = @inline (out, x) -> mul!(out, A, x)
mul_by!(A::T) where {T <: SimpleKronecker} = @inline (out, x) -> mul!(out, A, x)
mul_by!(A::AbstractSparseMatrix) = @inline (out, x) -> mul!(out, A, x)
function mul_by!(A::LinearAlgebra.AdjOrTrans{T, S}) where {T, S <: AbstractSparseMatrix}
@inline (out, x) -> mul!(out, A, x)
end

# out <- out + α * A * x
mul_by_accum!(A, α) = @inline (out, x) -> matmul!(out, A, x, α, One())
mul_by_accum!(A, α) = @inline (out, x) -> mul!(out, A, x, α, One())
function mul_by_accum!(A::AbstractSparseMatrix, α)
@inline (out, x) -> mul!(out, A, x, α, One())
end
Expand All @@ -33,6 +33,11 @@ mul_by_accum!(A::UniformScaling) = MulByAccumUniformScaling()
StructArrays.foreachfield(f, args...)
end

# Matrix{<:SVector} fallback
@inline function apply_to_each_field(f::F, args::Vararg{Any, N}) where {F, N}
f(args...)
end

# specialize for UniformScaling types: works for either StructArray{SVector} or Matrix{SVector}
# solution storage formats.
@inline apply_to_each_field(f::MulByUniformScaling, out, x, args...) = copy!(out, x)
Expand Down Expand Up @@ -136,12 +141,8 @@ function digest_boundary_conditions(boundary_conditions::NamedTuple{Keys, ValueT
return boundary_conditions
end

# Allocate nested array type for DGMulti solution storage.
function allocate_nested_array(uEltype, nvars, array_dimensions, dg)
# store components as separate arrays, combine via StructArrays
return StructArray{SVector{nvars, uEltype}}(ntuple(_ -> zeros(uEltype,
array_dimensions...),
nvars))
Comment on lines -139 to -144
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@chriselrod chriselrod May 23, 2024

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Out of curiosity, what's the motivation for the change and how does it perform?
The StructArray version should be SIMD-friendlier, while the Matrix{<:SVector} would be better if SIMD isn't possible.

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@jlchan jlchan May 24, 2024 •
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The motivation is due mainly to #1789. This impacts my specific Trixi solver DGMulti and locks Trixi.jl to a specific version of OrdinaryDiffEq. I looked at the array wrappers in RecursiveArrayTools.jl to try to address this, but it takes a lot more energy for me to figure out customizing broadcasting over custom arrays than just using Base.Array. I'm also concerned about changes like SciML/RecursiveArrayTools.jl#343.

My plan is to swap between Matrix{<:SVector{N, T}} and Array{T, 3} using unsafe_wrap, which is currently what Trixi does for other solvers too. My guess is that it won't be nearly as performant once we make these changes, since we have a few pieces of code which are accelerated by Octavian.jl and LoopVec.jl.

However, I'm less worried about efficiency at the moment and more about maintainability, which I think this would help with.

return zeros(SVector{nvars, uEltype}, array_dimensions...)
end

function reset_du!(du, dg::DGMulti, other_args...)
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6 changes: 0 additions & 6 deletions src/solvers/dgmulti/flux_differencing.jl
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Expand Up @@ -288,12 +288,6 @@ function compute_flux_differencing_SBP_matrices(dg::DGMultiFluxDiffSBP,
return Qrst_skew
end

# For flux differencing SBP-type approximations, store solutions in Matrix{SVector{nvars}}.
# This results in a slight speedup for `calc_volume_integral!`.
function allocate_nested_array(uEltype, nvars, array_dimensions, dg::DGMultiFluxDiffSBP)
return zeros(SVector{nvars, uEltype}, array_dimensions...)
end

function create_cache(mesh::DGMultiMesh, equations, dg::DGMultiFluxDiffSBP, RealT,
uEltype)
rd = dg.basis
Expand Down
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