If you're a user of DragonflyBSD, the next release of this popular BSD operating system is about to see huge performance improvements in its kernel if you're using a multi-core/processor system.
DragonflyBSD's Matthew Dillon has been working on some VM system concurrency and locking code, which previously had hindered the SMP performance of DragonflyBSD in some areas. Matthew's committed a big patch to DragonflyBSD (and should hopefully be in the next DragonflyBSD 2.12 release) that can lead to 1.47x performance improvements on a per-core basis, from the tests done on a quad-core AMD desktop system. On a four-socket 48-core Opteron workstation, there's also a performance win.
For those interested in DragonflyBSD, check out the results on their mailing list