One note for people planning to use AOLserver on *BSD and expect high loads: last time I checked, the threading library on FreeBSD was less than optimal, and it does not take advantage of multiple processors (it was doing something similar to the GNU pth library, by emulating threads in a single process). Things might have changed, so take this with a grain of salt :)
This is still true. However, for the single-CPU majority, this may
improve performance, because switching between threads doesn't require AOLserver to enter the kernel. I have seen grave warnings from the AOLserver types about userland threading such as FreeBSD's, but then the AOLserver people were probably used to 64-processor Sun boxes running Solaris. For many people here, it would be more apt to compare to a 2-processor box running Linux. I suspect that the performance gains of such a configuration over a FreeBSD box, if any, would be pretty modest—but I'm just speculating.
For more on where FreeBSD threading is, and where it's going, see http://people.freebsd.org/~jasone/kse.
