epoll is not an asyncio implementation, it really doesn’t belong in any discussion about aio, it’s a relatively better poll/select. Apparently less well known i

epoll is not an asyncio implementation, it really doesn’t belong in any discussion about aio, it’s a relatively better poll/select. Apparently less well known is that Linux had an async io interface also introduced around the same time in 2.5 (see io_setup, io_submit, and libaio). Initially extremely limited and generally not widely used (limitations include only working on certain disk files opened O_DIRECT), however it was incrementally improved over the years until io_uring came around. glibc has had a POSIX AIO implementation for years, implemented with userspace threads since the kernel implementation was originally not suitable.