Here's an interview with Marc Espie, Landry Breuil, Gilles Chehade, and Miod Vallat. It's in French. Even if your French is very poor like mine, it's worth taking some time to struggle through, I think. In particular, there's some interesting discussion of fine grained locking in the kernel vs. security vs. performance (though I need to read this again with a dictionary to fully understand it).
http://linuxfr.org/news/entretien-av...enbsd-partie-1