Weird Performance of SMatrix and Matrix on instruct!

[Roger-luo]

Weird Performance of SMatrix and Matrix on instruct!

[Roger-luo]

It will be more obvious when you pack a few instruct together, e.g using chained put blocks.

using StaticArrays, BenchmarkTools
U = @SMatrix rand(ComplexF64, 2, 2)
st = rand(ComplexF64, 1<<20)

julia> @benchmark foreach(k->instruct2!($st, $U, 2), 1:100)
BenchmarkTools.Trial:
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     180.581 ms (0.00% GC)
  median time:      186.595 ms (0.00% GC)
  mean time:        186.496 ms (0.00% GC)
  maximum time:     193.396 ms (0.00% GC)
  --------------
  samples:          27
  evals/sample:     1

julia> @benchmark foreach(k->instruct2!($st, $(Matrix(U)), 2), 1:100)
BenchmarkTools.Trial:
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     169.435 ms (0.00% GC)
  median time:      187.297 ms (0.00% GC)
  mean time:        188.134 ms (0.00% GC)
  maximum time:     208.341 ms (0.00% GC)
  --------------
  samples:          27
  evals/sample:     1

[Roger-luo]

But SMatrix should be faster

julia> @benchmark foreach(k->instruct3!($st, $U, 2), 1:100)
BenchmarkTools.Trial:
  memory estimate:  80 bytes
  allocs estimate:  1
  --------------
  minimum time:     10.900 ns (0.00% GC)
  median time:      13.812 ns (0.00% GC)
  mean time:        24.196 ns (38.99% GC)
  maximum time:     50.778 μs (99.92% GC)
  --------------
  samples:          10000
  evals/sample:     998

julia> @benchmark foreach(k->instruct3!($st, $(Matrix(U)), 2), 1:100)
BenchmarkTools.Trial:
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     63.906 ns (0.00% GC)
  median time:      67.717 ns (0.00% GC)
  mean time:        71.838 ns (0.00% GC)
  maximum time:     212.529 ns (0.00% GC)
  --------------
  samples:          10000
  evals/sample:     976