AIO network sockets and zero-copy under Linux

I have bee开发者_如何学运维n experimenting with async Linux network sockets (aio_read et al in aio.h/librt), and one thing i have been trying to find out is whether these are zero-copy or not. Pretty much all i have read so far discusses file I/O, whereas its network I/O i am interested in.

AIO is a bit of a pain to use and i suspect is non-portable, so wondering whether its worth persevering with it. Zero-copy is just about the only advantage (albiet a major one for my purposes) it would have over (non-blocking) select/epoll..

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In GLIBC, AIO is implemented using POSIX threads and a regular pread-call. So it's likely more expensive than select or epoll and doing the read or recv yourself.