Well, I know the basic about SystemTap, but I'm not so much familiarized with low-level stuff, I'll look for DTrace to see what's happening. Thanks for the information.
SystemTap is a Linux thing, which you can use on Linux to see how this works, but it won't be a pleasant experience.
DTrace is also available on FreeBSD, so if you look at what happens on Mac OS X, it might be helpful or insightful to also look at what happens on FreeBSD.
