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

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.