DTrace in the zone

The most interesting thing to me was this statement halfway through:

Given this, the name of the subroutine was obvious: it had to be getf() — the Unix routine that does exactly this in the kernel, and has since Fourth Edition Unix, circa 1973. (Aside: one of the reasons I love illumos is because of this heritage: compare the block comment above the Seventh Edition implementation of getf() to that above getf() currently in illumos — yes, we still have comments written by Ken!)

Troubleshooting with Dtrace specifically the Solaris variants (since Solaris contains the most probes) teaches you a lot of general Unix internals that usually only dedicated kernel/User land programmers would know.