I dealt with all of this in 2015, and spent three months trying to get epoll to perform similarly to kqueue; namely, to avoid returning on any and every packet received and, preferably, to abide by some sort of minimum bytes received (or connection closing) before returning.

Unless I'm missing something (and I could very well be missing something), I'm not seeing how that is any different than anything I tried...and I went through every socket option I could find, even if it seemed irrelevant.

Have you written code that actually performs this way? Or are you speculating? I really do wish I could do this with epoll, but I (and several others) just never were able to figure it out. And kqueue simply performed at least an order of magnitude better of any variation I could hack together with epoll.