Benchmarks

Here are some simple benchmarks. Take them with a grain of salt since they run on virtual machines in the cloud to generate the documentation automatically.

First-derivative operators

Periodic domains

Let's set up some benchmark code.

using BenchmarkTools
using LinearAlgebra, SparseArrays
using SummationByPartsOperators, DiffEqOperators

BLAS.set_num_threads(1) # make sure that BLAS is serial to be fair

T = Float64
xmin, xmax = T(0), T(1)

D_SBP = periodic_derivative_operator(derivative_order=1, accuracy_order=2,
                                     xmin=xmin, xmax=xmax, N=100)
x = grid(D_SBP)
D_DEO = CenteredDifference(derivative_order(D_SBP), accuracy_order(D_SBP),
                           step(x), length(x)) * PeriodicBC(eltype(D_SBP))

D_sparse = sparse(D_SBP)

u = randn(eltype(D_SBP), length(x)); du = similar(u);
@show D_SBP * u ≈ D_DEO * u ≈ D_sparse * u

function doit(D, text, du, u)
  println(text)
  sleep(0.1)
  show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D, $u))
  println()
end
doit (generic function with 1 method)

First, we benchmark the implementation from SummationByPartsOperators.jl.

doit(D_SBP, "D_SBP:", du, u)
D_SBP:
BenchmarkTools.Trial: 10000 samples with 993 evaluations.
 Range (minmax):  35.081 ns62.564 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     35.877 ns               GC (median):    0.00%
 Time  (mean ± σ):   36.062 ns ±  1.059 ns   GC (mean ± σ):  0.00% ± 0.00%

     ▃▆█▆▁                                                 
  ▂▄██████▇▆▅▄▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▂▂▁▁▁▁▁▁▁▂▁▁▂▁▁▂▂▂ ▃
  35.1 ns         Histogram: frequency by time        41.8 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

Next, we compare this to the runtime obtained using a sparse matrix representation of the derivative operator. Depending on the hardware etc., this can be an order of magnitude slower than the optimized implementation from SummationByPartsOperators.jl.

doit(D_sparse, "D_sparse:", du, u)
D_sparse:
BenchmarkTools.Trial: 10000 samples with 651 evaluations.
 Range (minmax):  190.602 ns267.813 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     201.668 ns                GC (median):    0.00%
 Time  (mean ± σ):   202.581 ns ±   4.391 ns   GC (mean ± σ):  0.00% ± 0.00%

                   ▂▄▆███▅▄▄▂▂▁▁▁            ▁               ▂
  ▄▃▅▅▅▆▄▆▆▅▆▇▇▄▆▅▇███████████████▇▇▇█▇█▇▇▇█████▇▇▆▆▇▆▅▆▅▆▆▅ █
  191 ns        Histogram: log(frequency) by time        220 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

Finally, we benchmark the implementation of the same derivative operator in DiffEqOperators.jl.

doit(D_DEO, "D_DEO:", du, u)
D_DEO:
┌ Warning: #= /home/runner/.julia/packages/DiffEqOperators/lHq9u/src/derivative_operators/convolutions.jl:412 =#:
`LoopVectorization.check_args` on your inputs failed; running fallback `@inbounds @fastmath` loop instead.
Use `warn_check_args=false`, e.g. `@turbo warn_check_args=false ...`, to disable this warning.
@ DiffEqOperators ~/.julia/packages/LoopVectorization/QgYWB/src/condense_loopset.jl:1166
┌ Warning: #= /home/runner/.julia/packages/DiffEqOperators/lHq9u/src/derivative_operators/convolutions.jl:460 =#:
`LoopVectorization.check_args` on your inputs failed; running fallback `@inbounds @fastmath` loop instead.
Use `warn_check_args=false`, e.g. `@turbo warn_check_args=false ...`, to disable this warning.
@ DiffEqOperators ~/.julia/packages/LoopVectorization/QgYWB/src/condense_loopset.jl:1166
BenchmarkTools.Trial: 10000 samples with 73 evaluations.
 Range (minmax):  837.329 ns106.266 μs   GC (min … max): 0.00% … 98.70%
 Time  (median):     859.685 ns                GC (median):    0.00%
 Time  (mean ± σ):   917.929 ns ±   2.076 μs   GC (mean ± σ):  4.50% ±  1.97%

   ▂▄▇███▆▅▄▃▃▂▂▂▂▂▃▄▃▂▂▁▂▂▂▁ ▁                               ▂
  ▆███████████████████████████████▇▇▇▆▇▇▇▇▇▇██████▆▇▇▇▆▆▆▆▆▅▅ █
  837 ns        Histogram: log(frequency) by time       1.04 μs <

 Memory estimate: 416 bytes, allocs estimate: 6.

These results were obtained using the following versions.

using InteractiveUtils
versioninfo()

using Pkg
Pkg.status(["SummationByPartsOperators", "DiffEqOperators"],
           mode=PKGMODE_MANIFEST)
Julia Version 1.6.7
Commit 3b76b25b64 (2022-07-19 15:11 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, generic)
Environment:
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager
      Status `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl/docs/Manifest.toml`
  [9fdde737] DiffEqOperators v4.45.0
  [9f78cca6] SummationByPartsOperators v0.5.61 `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl`

Bounded domains

We start again by setting up some benchmark code.

using BenchmarkTools
using LinearAlgebra, SparseArrays
using SummationByPartsOperators, BandedMatrices

BLAS.set_num_threads(1) # make sure that BLAS is serial to be fair

T = Float64
xmin, xmax = T(0), T(1)

D_SBP = derivative_operator(MattssonNordström2004(), derivative_order=1,
                            accuracy_order=6, xmin=xmin, xmax=xmax, N=10^3)
D_sparse = sparse(D_SBP)
D_banded = BandedMatrix(D_SBP)

u = randn(eltype(D_SBP), size(D_SBP, 1)); du = similar(u);
@show D_SBP * u ≈ D_sparse * u ≈ D_banded * u

function doit(D, text, du, u)
  println(text)
  sleep(0.1)
  show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D, $u))
  println()
end
doit (generic function with 1 method)

First, we benchmark the implementation from SummationByPartsOperators.jl.

doit(D_SBP, "D_SBP:", du, u)
D_SBP:
BenchmarkTools.Trial: 10000 samples with 199 evaluations.
 Range (minmax):  420.482 ns594.432 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     425.523 ns                GC (median):    0.00%
 Time  (mean ± σ):   427.212 ns ±   8.815 ns   GC (mean ± σ):  0.00% ± 0.00%

      ▄█                                                     
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  420 ns           Histogram: frequency by time          469 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

Again, we compare this to a representation of the derivative operator as a sparse matrix. No surprise - it is again much slower, as in periodic domains.

doit(D_sparse, "D_sparse:", du, u)
D_sparse:
BenchmarkTools.Trial: 10000 samples with 7 evaluations.
 Range (minmax):  4.453 μs 10.268 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     4.478 μs                GC (median):    0.00%
 Time  (mean ± σ):   4.506 μs ± 203.226 ns   GC (mean ± σ):  0.00% ± 0.00%

  ▇   ▂                                                     ▁
  █▅██▇▆▆▅▅▅▆▆▇▅▅▅▅▁▃▁▃▃▃▁▄▄▃▄▁▁▃▁▄▃▄▄▁▃▃▄▃▄▁▃▁▁▁▅▃▃▄▄▅▅▆▄ █
  4.45 μs      Histogram: log(frequency) by time       5.7 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

FInally, we compare it to a representation as banded matrix. Disappointingly, this is still much slower than the optimized implementation from SummationByPartsOperators.jl.

doit(D_banded, "D_banded:", du, u)
D_banded:
BenchmarkTools.Trial: 10000 samples with 5 evaluations.
 Range (minmax):  6.638 μs 16.094 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     6.658 μs                GC (median):    0.00%
 Time  (mean ± σ):   6.835 μs ± 919.710 ns   GC (mean ± σ):  0.00% ± 0.00%

   ▇█▆▄▅▄▄▄▄▁▃▄▄▆▇▆▆▄▅▄▄▇▄▃▄▄▄▁▁▃▁▃▄▃▃▃▁▃▃▃▅▇▆▆▆▆▅▆▆▄▅▅▅▄▆▆ █
  6.64 μs      Histogram: log(frequency) by time      12.4 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

These results were obtained using the following versions.

using InteractiveUtils
versioninfo()

using Pkg
Pkg.status(["SummationByPartsOperators", "BandedMatrices"],
           mode=PKGMODE_MANIFEST)
Julia Version 1.6.7
Commit 3b76b25b64 (2022-07-19 15:11 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, generic)
Environment:
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager
      Status `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl/docs/Manifest.toml`
  [aae01518] BandedMatrices v0.17.18
  [9f78cca6] SummationByPartsOperators v0.5.61 `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl`

Dissipation operators

We follow the same structure as before. At first, we set up some benchmark code.

using BenchmarkTools
using LinearAlgebra, SparseArrays
using SummationByPartsOperators, BandedMatrices

BLAS.set_num_threads(1) # make sure that BLAS is serial to be fair

T = Float64
xmin, xmax = T(0), T(1)

D_SBP = derivative_operator(MattssonNordström2004(), derivative_order=1,
                            accuracy_order=6, xmin=xmin, xmax=xmax, N=10^3)
Di_SBP  = dissipation_operator(MattssonSvärdNordström2004(), D_SBP)
Di_sparse = sparse(Di_SBP)
Di_banded = BandedMatrix(Di_SBP)
Di_full   = Matrix(Di_SBP)

u = randn(eltype(D_SBP), size(D_SBP, 1)); du = similar(u);
@show Di_SBP * u ≈ Di_sparse * u ≈ Di_banded * u ≈ Di_full * u

function doit(D, text, du, u)
  println(text)
  sleep(0.1)
  show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D, $u))
  println()
end
doit (generic function with 1 method)

At first, let us benchmark the derivative and dissipation operators implemented in SummationByPartsOperators.jl.

doit(D_SBP, "D_SBP:", du, u)
doit(Di_SBP, "Di_SBP:", du, u)
D_SBP:
BenchmarkTools.Trial: 10000 samples with 201 evaluations.
 Range (minmax):  391.433 ns716.164 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     396.617 ns                GC (median):    0.00%
 Time  (mean ± σ):   398.052 ns ±   9.498 ns   GC (mean ± σ):  0.00% ± 0.00%

       ▆█                                                     
  ▂▂▂▄███▄▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▁▂▁▁▁▂▁▁▂▁▂▁▂▁▂▂▂▁▁▂▁▂▂▁▁▁▂▂▂▂▂▂▂▂▂ ▃
  391 ns           Histogram: frequency by time          438 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
Di_SBP:
BenchmarkTools.Trial: 10000 samples with 10 evaluations.
 Range (minmax):  1.062 μs 2.895 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     1.072 μs               GC (median):    0.00%
 Time  (mean ± σ):   1.077 μs ± 56.648 ns   GC (mean ± σ):  0.00% ± 0.00%

       █▁                                                   
  ▂▂▂▆▆██▅▅▅▃▃▂▂▂▂▁▁▁▂▁▁▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▂▁▂▁▂▁▁▂▁▁▁▁▂▁▂▂▂▂ ▃
  1.06 μs        Histogram: frequency by time        1.15 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Next, we compare the results to sparse matrix representations. It will not come as a surprise that these are again much (around an order of magnitude) slower.

doit(Di_sparse, "Di_sparse:", du, u)
doit(Di_banded, "Di_banded:", du, u)
Di_sparse:
BenchmarkTools.Trial: 10000 samples with 6 evaluations.
 Range (minmax):  5.135 μs  8.910 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     5.176 μs                GC (median):    0.00%
 Time  (mean ± σ):   5.205 μs ± 207.102 ns   GC (mean ± σ):  0.00% ± 0.00%

  ▄█   ▁▁                                                    ▁
  ██▇███▆▅▇▆▃▆▆▇▅▄▅▅▄▅▁▁▁▁▃▃▁▁▁▃▁▃▁▁▃▁▁▁▃▁▃▁▁▄▁▁▁▁▁▁▃▁▃▅▅▆▆ █
  5.13 μs      Histogram: log(frequency) by time      6.57 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.
Di_banded:
BenchmarkTools.Trial: 10000 samples with 5 evaluations.
 Range (minmax):  6.172 μs 13.824 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     6.192 μs                GC (median):    0.00%
 Time  (mean ± σ):   6.403 μs ± 396.694 ns   GC (mean ± σ):  0.00% ± 0.00%

  █              ▅▆    ▁                                ▁
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  6.17 μs      Histogram: log(frequency) by time      7.92 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Finally, let's benchmark the same computation if a full (dense) matrix is used to represent the derivative operator. This is obviously a bad idea but 🤷

doit(Di_full, "Di_full:", du, u)
Di_full:
BenchmarkTools.Trial: 10000 samples with 1 evaluation.
 Range (minmax):  136.816 μs333.224 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     138.159 μs                GC (median):    0.00%
 Time  (mean ± σ):   140.088 μs ±   5.678 μs   GC (mean ± σ):  0.00% ± 0.00%

   ▅█▆▅▃▂▁▁▁               ▁▁▁▁▁▁▂▁▁                          ▂
  ███████████▇▇▆▆▆▅▅▅▄▆▆▆▆███████████████▇▇▆▅▄▆▅▄▄▅▄▆▅▅▆▆▄▅▆▆ █
  137 μs        Histogram: log(frequency) by time        161 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

These results were obtained using the following versions.

using InteractiveUtils
versioninfo()

using Pkg
Pkg.status(["SummationByPartsOperators", "BandedMatrices"],
           mode=PKGMODE_MANIFEST)
Julia Version 1.6.7
Commit 3b76b25b64 (2022-07-19 15:11 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, generic)
Environment:
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager
      Status `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl/docs/Manifest.toml`
  [aae01518] BandedMatrices v0.17.18
  [9f78cca6] SummationByPartsOperators v0.5.61 `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl`

Structure-of-Arrays (SoA) and Array-of-Structures (AoS)

SummationByPartsOperators.jl tries to provide efficient support of

To demonstrate this, let us set up some benchmark code.

using BenchmarkTools
using StaticArrays, StructArrays
using LinearAlgebra, SparseArrays
using SummationByPartsOperators

BLAS.set_num_threads(1) # make sure that BLAS is serial to be fair

struct Vec5{T} <: FieldVector{5,T}
  x1::T
  x2::T
  x3::T
  x4::T
  x5::T
end

# Apply `mul!` to each component of a plain array of structures one after another
function mul_aos!(du, D, u, args...)
  for i in 1:size(du, 1)
    mul!(view(du, i, :), D, view(u, i, :), args...)
  end
end

T = Float64
xmin, xmax = T(0), T(1)

D_SBP = derivative_operator(MattssonNordström2004(), derivative_order=1,
                            accuracy_order=4, xmin=xmin, xmax=xmax, N=101)
D_sparse = sparse(D_SBP)
D_full   = Matrix(D_SBP)
101×101 Matrix{Float64}:
 -141.176    173.529   -23.5294   …    0.0         0.0       0.0
  -50.0        0.0      50.0           0.0         0.0       0.0
    9.30233  -68.6047    0.0           0.0         0.0       0.0
    3.06122    0.0     -60.2041        0.0         0.0       0.0
    0.0        0.0       8.33333       0.0         0.0       0.0
    0.0        0.0       0.0      …    0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    ⋮                             ⋱                          ⋮
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0           0.0         0.0       0.0
    0.0        0.0       0.0      …    0.0         0.0       0.0
    0.0        0.0       0.0          -8.33333     0.0       0.0
    0.0        0.0       0.0          60.2041      0.0      -3.06122
    0.0        0.0       0.0           0.0        68.6047   -9.30233
    0.0        0.0       0.0         -50.0         0.0      50.0
    0.0        0.0       0.0      …   23.5294   -173.529   141.176

At first, we benchmark the application of the operators implemented in SummationByPartsOperators.jl and their representations as sparse and dense matrices in the scalar case. As before, the sparse matrix representation is around an order of magnitude slower and the dense matrix representation is far off.

println("Scalar case")
u = randn(T, size(D_SBP, 1)); du = similar(u)
println("D_SBP")
show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D_SBP, $u))
println("\nD_sparse")
show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D_sparse, $u))
println("\nD_full")
show(stdout, MIME"text/plain"(), @benchmark mul!($du, $D_full, $u))
Scalar case
D_SBP
BenchmarkTools.Trial: 10000 samples with 984 evaluations.
 Range (minmax):  56.213 ns100.462 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     56.803 ns                GC (median):    0.00%
 Time  (mean ± σ):   57.155 ns ±   1.883 ns   GC (mean ± σ):  0.00% ± 0.00%

   ▂██                                                       
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  56.2 ns         Histogram: frequency by time         65.8 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_sparse
BenchmarkTools.Trial: 10000 samples with 231 evaluations.
 Range (minmax):  319.385 ns529.130 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     328.017 ns                GC (median):    0.00%
 Time  (mean ± σ):   330.202 ns ±  10.649 ns   GC (mean ± σ):  0.00% ± 0.00%

       ▁▄▇█▇                                                 
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  319 ns           Histogram: frequency by time          372 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_full
BenchmarkTools.Trial: 10000 samples with 10 evaluations.
 Range (minmax):  1.705 μs 4.072 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     1.722 μs               GC (median):    0.00%
 Time  (mean ± σ):   1.734 μs ± 98.862 ns   GC (mean ± σ):  0.00% ± 0.00%

  ▇                                                       ▂
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  1.71 μs      Histogram: log(frequency) by time     2.38 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Next, we use a plain array of structures (AoS) in the form of a two-dimensional array and our custom mul_aos! implementation that loops over each component, using mul! on views. Here, the differences between the timings are less pronounced.

println("Plain Array of Structures")
u_aos_plain = randn(T, 5, size(D_SBP, 1)); du_aos_plain = similar(u_aos_plain)
println("D_SBP")
show(stdout, MIME"text/plain"(), @benchmark mul_aos!($du_aos_plain, $D_SBP, $u_aos_plain))
println("\nD_sparse")
show(stdout, MIME"text/plain"(), @benchmark mul_aos!($du_aos_plain, $D_sparse, $u_aos_plain))
println("\nD_full")
show(stdout, MIME"text/plain"(), @benchmark mul_aos!($du_aos_plain, $D_full, $u_aos_plain))
Plain Array of Structures
D_SBP
BenchmarkTools.Trial: 10000 samples with 10 evaluations.
 Range (minmax):  1.380 μs 3.083 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     1.394 μs               GC (median):    0.00%
 Time  (mean ± σ):   1.399 μs ± 63.109 ns   GC (mean ± σ):  0.00% ± 0.00%

     ▂▆█                                                  
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  1.38 μs        Histogram: frequency by time        1.51 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_sparse
BenchmarkTools.Trial: 10000 samples with 9 evaluations.
 Range (minmax):  2.380 μs  4.892 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     2.467 μs                GC (median):    0.00%
 Time  (mean ± σ):   2.484 μs ± 119.036 ns   GC (mean ± σ):  0.00% ± 0.00%

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  2.38 μs         Histogram: frequency by time        3.12 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_full
BenchmarkTools.Trial: 10000 samples with 3 evaluations.
 Range (minmax):  8.913 μs 17.109 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     8.983 μs                GC (median):    0.00%
 Time  (mean ± σ):   9.031 μs ± 368.772 ns   GC (mean ± σ):  0.00% ± 0.00%

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  8.91 μs      Histogram: log(frequency) by time      11.3 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Now, we use an array of structures (AoS) based on reinterpret and standard mul!. This is much more efficient for the implementation in SummationByPartsOperators.jl. In Julia v1.6, this is also more efficient for sparse matrices but less efficient for dense matrices (compared to the plain AoS approach with mul_aos! above).

println("Array of Structures (reinterpreted array)")
u_aos_r = reinterpret(reshape, Vec5{T}, u_aos_plain); du_aos_r = similar(u_aos_r)
@show D_SBP * u_aos_r ≈ D_sparse * u_aos_r ≈ D_full * u_aos_r
mul!(du_aos_r, D_SBP, u_aos_r)
@show reinterpret(reshape, T, du_aos_r) ≈ du_aos_plain
println("D_SBP")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos_r, $D_SBP, $u_aos_r))
println("\nD_sparse")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos_r, $D_sparse, $u_aos_r))
println("\nD_full")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos_r, $D_full, $u_aos_r))
Array of Structures (reinterpreted array)
D_SBP * u_aos_r ≈ D_sparse * u_aos_r ≈ D_full * u_aos_r = true
reinterpret(reshape, T, du_aos_r) ≈ du_aos_plain = true
D_SBP
BenchmarkTools.Trial: 10000 samples with 496 evaluations.
 Range (minmax):  218.857 ns292.351 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     221.099 ns                GC (median):    0.00%
 Time  (mean ± σ):   222.508 ns ±   6.029 ns   GC (mean ± σ):  0.00% ± 0.00%

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  219 ns        Histogram: log(frequency) by time        258 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_sparse
BenchmarkTools.Trial: 10000 samples with 185 evaluations.
 Range (minmax):  556.989 ns784.168 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     571.611 ns                GC (median):    0.00%
 Time  (mean ± σ):   573.906 ns ±  10.884 ns   GC (mean ± σ):  0.00% ± 0.00%

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  557 ns           Histogram: frequency by time          620 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_full
BenchmarkTools.Trial: 10000 samples with 4 evaluations.
 Range (minmax):  7.416 μs 19.008 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     7.484 μs                GC (median):    0.00%
 Time  (mean ± σ):   7.650 μs ± 846.643 ns   GC (mean ± σ):  0.00% ± 0.00%

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  7.42 μs      Histogram: log(frequency) by time      12.5 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Next, we still use an array of structures (AoS), but copy the data into a plain Array instead of using the reinterpreted versions. There is no significant difference to the previous version in this case.

println("Array of Structures")
u_aos = Array(u_aos_r); du_aos = similar(u_aos)
@show D_SBP * u_aos ≈ D_sparse * u_aos ≈ D_full * u_aos
mul!(du_aos, D_SBP, u_aos)
@show du_aos ≈ du_aos_r
println("D_SBP")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos, $D_SBP, $u_aos))
println("\nD_sparse")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos, $D_sparse, $u_aos))
println("\nD_full")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_aos, $D_full, $u_aos))
Array of Structures
D_SBP * u_aos ≈ D_sparse * u_aos ≈ D_full * u_aos = true
du_aos ≈ du_aos_r = true
D_SBP
BenchmarkTools.Trial: 10000 samples with 487 evaluations.
 Range (minmax):  218.725 ns361.189 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     224.177 ns                GC (median):    0.00%
 Time  (mean ± σ):   225.129 ns ±   5.889 ns   GC (mean ± σ):  0.00% ± 0.00%

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  219 ns        Histogram: log(frequency) by time        256 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_sparse
BenchmarkTools.Trial: 10000 samples with 181 evaluations.
 Range (minmax):  583.635 ns853.972 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     598.691 ns                GC (median):    0.00%
 Time  (mean ± σ):   601.217 ns ±  13.691 ns   GC (mean ± σ):  0.00% ± 0.00%

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  584 ns           Histogram: frequency by time          660 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_full
BenchmarkTools.Trial: 10000 samples with 4 evaluations.
 Range (minmax):  7.452 μs 18.540 μs   GC (min … max): 0.00% … 0.00%
 Time  (median):     7.504 μs                GC (median):    0.00%
 Time  (mean ± σ):   7.546 μs ± 344.233 ns   GC (mean ± σ):  0.00% ± 0.00%

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  7.45 μs      Histogram: log(frequency) by time      9.48 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Finally, let's look at a structure of arrays (SoA). Interestingly, this is slower than the array of structures we used above. On Julia v1.6, the sparse matrix representation performs particularly bad in this case.

println("Structure of Arrays")
u_soa = StructArray(u_aos); du_soa = similar(u_soa)
@show D_SBP * u_soa ≈ D_sparse * u_soa ≈ D_full * u_soa
mul!(du_soa, D_SBP, u_soa)
@show du_soa ≈ du_aos
println("D_SBP")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_soa, $D_SBP, $u_soa))
println("\nD_sparse")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_soa, $D_sparse, $u_soa))
println("\nD_full")
show(stdout, MIME"text/plain"(), @benchmark mul!($du_soa, $D_full, $u_soa))
Structure of Arrays
D_SBP * u_soa ≈ D_sparse * u_soa ≈ D_full * u_soa = true
du_soa ≈ du_aos = true
D_SBP
BenchmarkTools.Trial: 10000 samples with 417 evaluations.
 Range (minmax):  237.254 ns303.974 ns   GC (min … max): 0.00% … 0.00%
 Time  (median):     239.249 ns                GC (median):    0.00%
 Time  (mean ± σ):   240.052 ns ±   4.297 ns   GC (mean ± σ):  0.00% ± 0.00%

   ▃▆▇█▇▆▄▃▂▁                                                 ▂
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  237 ns        Histogram: log(frequency) by time        260 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.
D_sparse
BenchmarkTools.Trial: 10000 samples with 1 evaluation.
 Range (minmax):  214.151 μs 11.808 ms   GC (min … max):  0.00% … 61.65%
 Time  (median):     223.568 μs                GC (median):     0.00%
 Time  (mean ± σ):   279.165 μs ± 488.971 μs   GC (mean ± σ):  11.00% ±  6.14%

   ▃██▄▃▃▃▂▁                                        ▁▄▅▄▂▁▁    ▂
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  214 μs        Histogram: log(frequency) by time        370 μs <

 Memory estimate: 328.25 KiB, allocs estimate: 10504.
D_full
BenchmarkTools.Trial: 10000 samples with 1 evaluation.
 Range (minmax):  176.491 μs 13.073 ms   GC (min … max):  0.00% … 52.70%
 Time  (median):     183.583 μs                GC (median):     0.00%
 Time  (mean ± σ):   236.160 μs ± 464.883 μs   GC (mean ± σ):  12.21% ±  6.16%

  ▃▆█▅▃▃▃▂▁ ▁                                        ▄▄▄▃▂▁▁   ▂
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  176 μs        Histogram: log(frequency) by time        322 μs <

 Memory estimate: 328.25 KiB, allocs estimate: 10504.

These results were obtained using the following versions.

using InteractiveUtils
versioninfo()

using Pkg
Pkg.status(["SummationByPartsOperators", "StaticArrays", "StructArrays"],
           mode=PKGMODE_MANIFEST)
Julia Version 1.6.7
Commit 3b76b25b64 (2022-07-19 15:11 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, generic)
Environment:
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager
      Status `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl/docs/Manifest.toml`
  [90137ffa] StaticArrays v1.9.3
  [09ab397b] StructArrays v0.6.18
  [9f78cca6] SummationByPartsOperators v0.5.61 `~/work/SummationByPartsOperators.jl/SummationByPartsOperators.jl`