Having followed most of the comments on both these threads, I don't think it's fair to characterize Zed's position as saying "epoll is always bad". I think a be

Having followed most of the comments on both these threads, I don't think it's fair to characterize Zed's position as saying "epoll is always bad". I think a better characterization would be: "epoll is not automagically better under every imaginable scenario". You may argue that nobody is making any such claim, but I can tell you that the sections of the blogosphere I skim via HN, reddit, etc. do imply it. Maybe the authors just assume everyone can infer that every decision has tradeoffs and there's no need to discuss them in depth for this particular case, or maybe—and the nature of the blogosphere leaves me inclined to think that this is the case—most of those authors never consciously thought about those tradeoffs because epoll happens to be a good fit for their particular problem. Either way, Zed is the first person I've seen trying to explicitly identify and quantify those trade-offs for poll vs. epoll. As such, I think he's doing the community a service. If this research leads to a better implementation of epoll, or a server that requires less tuning to do well under a particular load, that is great for everyone. Even if it doesn't lead to any great improvements, a better-educated developer population that makes more informed decisions is still a net win for the world.