MTK-generated ODEFunction evaluates more slowly than hand-written function

[vyudu]

Seems like the MTK-generated is ~5x slower than a corresponding hand-written function

using ModelingToolkit
using BenchmarkTools
using SciMLBase
t = ModelingToolkit.t_nounits; D = ModelingToolkit.D_nounits

@parameters α β γ δ
@variables x(t) y(t)
    
eqs = [D(x) ~ α * x - β * x * y,
       D(y) ~ -γ * y + δ * x * y]
    
@mtkbuild sys = ODESystem(eqs, t)
f1 = ODEFunction(sys)
f2 = ODEFunction(sys; eval_expression = true)
f3 = ODEFunction{true, SciMLBase.FullSpecialize}(sys)
f4 = ODEFunction{true, SciMLBase.FullSpecialize}(sys; eval_expression = true)

function lotkavolterra!(du, u, p, t) 
    du[1] = p[1]*u[1] - p[2]*u[1]*u[2]
    du[2] = -p[4]*u[2] + p[3]*u[1]*u[2]
end

du = zeros(2); u = rand(2); p = rand(4); t_ = 0.

@btime f1(du,u,p,t_) # 93.335 ns
du = zeros(2)
@btime f2(du,u,p,t_) # 92.068 ns
du = zeros(2)
@btime f3(du,u,p,t_) # 88.889 ns
du = zeros(2)
@btime f4(du,u,p,t_) # 85.842 ns
du = zeros(2)
@btime lotkavolterra!(du,u,p,t_) # 17.368 ns

[baggepinnen]

All f functions are global variables, do the timings change if you interpolate those into the benchmarked expression?

[vyudu]

Ah yeah that's what was going on. Interpolating everything gives 5.500 ns for all the generated ones and 4.500 ns for the handwritten one. Not sure if that's expected, if so feel free to close this.

[baggepinnen]

Try interpolation also the input arrays to make sure there's no difference