As i compared https://github.com/pkhuong/tiny_batcher/blob/main/reference.py with the expected number of compare-exchange for Batcher's odd-even merge sort, it became clear that Knuth's Algorithm M isn't that (5.2.2, p111 in TAoCP vol 3 2nd ed).

Is there a reference for the exact number of compare-exchange I should expect for small n?

@jix maybe?