epoll bare minimum echo server

• uses an event loop created with epoll

install and run

make

./epoll_echo_server [port_number]

compare with io_uring echo server

https://github.com/frevib/io_uring-echo-server

Benchmarks

https://github.com/frevib/io_uring-echo-server/blob/io-uring-feat-fast-poll/benchmarks/benchmarks.md#benchmark-results-requestssecond