hoge.jl

using BechmarkTools

# https://ja.coder.work/so/julia/715798

function test1!(foo1,foo2,foo3)
    foo3 = foo1 + foo2;
    return foo3
end

function test2!(foo1,foo2,foo3)
    @. foo3 = foo1 + foo2;
    return foo3
end

function test3!(foo1,foo2,foo3)
    for i in eachindex(foo2)
        foo3[i] = foo1[i] + foo2[i]
     end
    return foo3
end

N = 10000;
foo1 = rand(N,N);
foo2 = rand(N,N);

foo3 = similar(foo1);

@benchmark test1!(foo1,foo2,foo3)
@benchmark test2!(foo1,foo2,foo3)
@benchmark test3!(foo1,foo2,foo3)

"""
julia> @benchmark test1!(foo1,foo2,foo3)
BenchmarkTools.Trial: 
  memory estimate:  762.94 MiB
  allocs estimate:  2
  --------------
  minimum time:     344.411 ms (0.09% GC)
  median time:      376.076 ms (8.35% GC)
  mean time:        377.700 ms (8.30% GC)
  maximum time:     414.821 ms (17.22% GC)
  --------------
  samples:          14
  evals/sample:     1

julia> @benchmark test2!(foo1,foo2,foo3)
BenchmarkTools.Trial: 
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     139.872 ms (0.00% GC)
  median time:      142.623 ms (0.00% GC)
  mean time:        143.080 ms (0.00% GC)
  maximum time:     147.802 ms (0.00% GC)
  --------------
  samples:          35
  evals/sample:     1

julia> @benchmark test3!(foo1,foo2,foo3)
BenchmarkTools.Trial: 
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     131.975 ms (0.00% GC)
  median time:      133.445 ms (0.00% GC)
  mean time:        134.389 ms (0.00% GC)
  maximum time:     145.454 ms (0.00% GC)
  --------------
  samples:          38
  evals/sample:     1
"""