But even with IOCP, Windows IIS implements request handling as a kernel module to accelerate it, and yet still isn't faster than nginx on linux with many cpu co

But even with IOCP, Windows IIS implements request handling as a kernel module to accelerate it, and yet still isn't faster than nginx on linux with many cpu cores. https://www.rootusers.com/wp-content/uploads/2017/01/iis-linux-webservers-8-cpu-cores.png https://www.rootusers.com/wp-content/uploads/2017/01/iis-lin... But can be noticeably faster on fewer cores: https://www.rootusers.com/linux-vs-windows-web-server-benchmarks/ https://www.rootusers.com/linux-vs-windows-web-server-benchm... But still in many cases has more performance pitfalls in practice: http://serverfault.com/questions/317199/linux-vs-windows-7-web-server-performance-differences http://serverfault.com/questions/317199/linux-vs-windows-7-w... So, sure, epoll() does not help for optimal distribution of accept() or read() of the same fds over multiple threads. But even with a single thread accepting, or with "thundering herd" problems of other strategies, linux is still usually more efficient in practice. Often dumb non-optimal designs are faster just due to subtle problems caused by overall system complexity. Side note: macOS has kqueue, but it's been buggy in enough releases that libevent and libev usually have to use select() on macOS to be safe. http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#OS_X_AND_DARWIN_BUGS http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#OS_X_AN... https://github.com/libevent/libevent/pull/377 https://github.com/libevent/libevent/pull/377 So for your "optimal socket handling" tasks you're really limited to choosing between Linux and FreeBSD, and there are other issues to consider there, like drivers.