signalfd does NOT work the same as kqueue EVFILT_SIGNAL. On Linux signalfd basically behaves the same as installing a signal handler--only a single signalfd obj

signalfd does NOT work the same as kqueue EVFILT_SIGNAL. On Linux signalfd basically behaves the same as installing a signal handler--only a single signalfd object will receive a signal, so whether installing a signal handler or a signalfd listener you're changing behavior globally. It's even messier than that, because signalfd only works if there are no other signal handlers installed. By contrast, with kqueue all EVFILT_SIGNAL listeners will be notified of a signal, even if the signal was also delivered to a handler. Big difference. This is one among many reasons why Linux's event syscalls are widely considered inferior to BSD kqueue. It's ridiculous considering that kqueue not only predated epoll by several years and signalfd by nearly a decade, with ample use cases, it was well documented in a paper that described the rationale for all the semantics. Somehow the authors of epoll, signalfd, etc couldn't even bothered do to basic research; they just spitballed semantics without having much real-world experience about what was needed and most useful.