High-Performance Programming Techniques on Linux
Dejected @Work writes "A senior IBM developer has come out with a series of articles on high performance Linux programming techniques using pipes, sockets, threads, and processes. The series has been running for a while and juxtaposes these high performance technique with Linux and Windows. Guess who wins?"
multi-threading is why, for example aolserver can do with one process what apache needs a bunch of processes to do. (though i digress, aolserver only has to run tcl interps, where apache is much more versatile.)
meanwhile, both FreeBSD and NetBSD are trying to get SMP and scheduler activations into their kernels. this would improve their support for multi-threading substantially. there's a paper which explains this better than i ever could.