zero-cost SDT probes

[Simon J. Gerraty]

Mark Johnston <markj at freebsd.org> wrote:
> For the past while I've been experimenting with various ways to
> implement "zero-cost" SDT DTrace probes. Basically, at the moment an SDT
> probe site expands to this:

Would it be feasible to compile the probes into the kernel
as active calls to a registrar function?
That would eliminate all the complexity of finding PC's
though you'd probably need to pass extra args to convey the point of the
probe?

It would hurt boot time a little too - each probe point would make a
call to register itself (and get overwritten with nops as a reward) but
very simple?