whereas libev is Linux-specific IIRC.
Libev is a polling abstraction. It has select, epoll and kqueue backends (and there may be others I don't know about). So it is particulary useful for unices, where epoll (linux) and kqueue (OSX and BSD) are preferred async IO mechanisms. It can also be used on Windows, but with the select() backend, which doesn't scale well with many file descriptors. select() is also limited to 64 file descriptors by default on windows IIRC (that limit can be raised, but only to 4096 if I am not mistaken).
