I added some special support for tracking down use of mutexes in realtime threads. It's a very simple extension that -- if enabled -- checks on each mutex operation wheter it is executed by a realtime thread or not. (--track-rt) The output of a test run of this you can find in this announcement on LAD. Particularly interesting is that you can use this to track down which mutexes are good candidates for priority inheritance.
The mutrace tarball now also includes a companion tool matrace that can be used to track down memory allocation operations in realtime threads. See the same lad announcement as above for example output of this tool.
Finally, after my comments on the locking hotspots in glib's type system, Wim Taymans and Edward Hervey worked on turning the mutex-emulated rwlocks into OS native ones with quite positive results, for more information see this bug.
As soon as my review request is fully processed mutrace will be available in rawhide.
A snapshot tarball of mutrace you may find here (despite the name of the tarball that's just a snapshot, not the real release 0.1), for all those folks who are afraid of git, or don't have a current autoconf/automake/libtool installed.