What is the runtime complexity of the `BLAKE2` hash function? Assume you want to calculate the blake2 hash function for an arbitrary input of $n$ bytes. I am wondering about the runtime, in particular:

Does the runtime of scale linearly with the input length, i.e., can the runtime of blake2 be estimated as O(n)?
Is the landau even something that is sensible here, given how optimized cryptographic operations are on modern day processors (say on an intel-i7)
Blake2 takes (in either variant) the input, processes it in fixed-size blocks, padding the last block with zeroes to the full block size if required. The processing operation happens in constant time (it takes a constant number of cycles, big-O notation is meaningless since the input size is fixed). The initialization and finalization steps also take constant time. Therefore, the overall operation takes $O(n)$ time.