Graph execution time as a function of the size of the input

There should be a way of graphing the execution time as a function of the size of the input, so that one can demonstrate the time complexity of the algorithm empirically in graphs like this:


The size of the input can't be determined automatically, but it could given by the user in the form of a tuple: `{input_size, input_value}` or some similar API. I understand that this might require a new top-level Benchee function, and that might be a change too big to implement.

But even if this change isn't possible, just plotting the execution time of all the inputs in the same graph would be a big improvement.

In my concrete example, I want to show that a an implementation of a programming language lexer (let's say, implementation 1) has complexity roughly linear on the size of the file while the alternative impelmentation (say, implementation 2) has supralinear complexity. I can see how, as the input size rows, implementation 2 gets slower and slower than implementation 1, but I can't compare the execution time of the implementation 1 with itself as the input grows.