FWIW, I've written an async webserver which handles a few thousand concurrent users, and does thousands of HTTP reqs/second. I've never seen poll/epoll as a bottleneck, but I'm using Java NIO which really seems to work extremely well (I don't remember how/which it uses, I think epoll).

Maybe Java does some of this cool stuff already so perhaps I'm shielded from the pain of dealing with things directly.

In the past I've written Java NIO code that dealt with around 60,000 concurrent connections pretty well. The time spent doing poll seemed to be completely insignificant. CPU usage was negligible.

It'd be good to see some numbers though - for example:

For average mongrel application, 40% of CPU time is spent in poll / average of 30ms latency is due to poll etc.

But I'm skeptical those numbers are true. That was my point.

If you don't start with those numbers and measurements, optimizations like this, whilst interesting, may end up being of no real use to anyone.