I have a small suggestion for C programmers: please don't use staticfunction local variables. Yes, I know, they've been part of C for avery long time, they are kind of nifty, and they're sometimes nice. Butstill, please use a file level static variable instead, which has justthe same effects.

Well, almost. There is one important difference; in practice, manymore tools can find and inspect file level static variables than canfind and inspect function static

The fine documentation for DTrace's kernel function tracer contains a little note that you mighteasily miss if, like me, you were just skimming:

For each instruction set, there are a small number of functions thatdo not call other functions and are highly optimized by the compiler(so-called leaf functions ) that cannot be instrumented by FBT.

The first thing to know is that DTrace does not have any useful errormessages when you run into this. Instead of a helpful note about, say,'this