This is a first attempt at documenting some of the more "standard" DTrace providers in FreeBSD. We don't currently have any documentation for static probes, so I had to come up with some conventions. They're obviously not set in stone yet, so please feel free to suggest sweeping changes in addition to the usual wording/consistency/completeness issues.
The main reference for Solaris DTrace providers are pages on the Oracle wiki, e.g. https://wikis.oracle.com/display/DTrace/ip+Provider
I followed a roughly similar format: each provider gets its own man page, the probes are described in the DESCRIPTION section, argument types are described in ARGUMENTS, and some examples are under EXAMPLES. Probe names are rendered using the .Fn macro; this isn't really ideal, but I don't see any good alternatives. In general, I try to describe the conditions under which a given probe will fire, as well as the arguments it receives. Rendered pages are here: https://people.freebsd.org/~markj/dtrace/man/
As mentioned, this covers only a subset of the SDT providers that we have. Most of the rest are less complete and mainly intended for developer debugging, so they're not very amenable to documentation.