Just a quick and somehow interesting observation: Linus assumes that the
read buffer is page-aligned in this comparison, something you cannot
expect in most higher languages (of course you can arrange that in
libsndfile - did you?).
Right, this is an unwarranted assumption. Furthermore, for certain applications with complex access patterns I'd expect it to be way easier for the user to use mmap efficiently. Even assuming that "read" were always faster, implementing your own complex buffer management to cache data efficiently for particular access patterns may not be easy. Unless your name is Linus, of course... ;-)
That reminds me that the OS guys live in another
world. Would be interesting which function wins if you compare
Unix.read
(which does not care about alignment, and does an extra copy) with
Bigarray.mmap.