[$] A new kernel polling interface

Polling a set of file descriptors to see which ones can perform I/O withoutblocking is a useful thing to do - so useful that the kernel provides threedifferent system calls (select(),poll(),and epoll_wait()- plus some variants) to perform it. But sometimes three is not enough;there is now a proposal circulating for a fourth kernel polling interface.As is usually the case, the motivation for this change is performance.