The DragonFly BSD project has recently decided to hold off on the 2.12 release to address a couple of long-standing issues. Some of the disruptive work done to address these issues has also resulted in the MP Token (giant kernel lock) and other major contention points being finally pushed out of the way of all critical paths. The result?
Greatly improved scalability. DragonFly BSD 2.13 is now on par with FreeBSD 10 in the PostgreSQL pgbench test on single-socket multi-core systems. The test setup notes and a plot of results are available.
Francois Tigeot has also done some similar testing on a larger 2-socket Intel machine, which shows DragonFly still trails FreeBSD under these circumstances but is enormously improved with respect to the previous release. There’s a mailing list post about this one (and here’s a direct link to results).