Performance of select/poll vs asynchronous I/O

Question

From a performance standpoint, which one is better? select/poll or asynchronous I/O? My earlier impression was select/poll repeatedly asks the kernel for data, whereas asynchron

Answer 1

With async I/O, you have to loop continiously and check to see if there is new data to read periodically. This makes it CPU intensive. Select/poll simply blocks, taking up no CPU power. It does not loop internally.