http://www.netbsd.org/Changes/#merge-nathanw_sa
After NetBSD supports symmetric multiprocessing (SMP) on a number of

systems for some time now, support for native threads was added by merging

the nathan_sw branch that contains a Scheduler Activations based threads

implementation by Nathan Williams and Jason Thorpe.
SMP means running processes on more than one CPU in parallel. (With some

care-taking from the kernel that both CPUs don't step on each other with

respect to writing to kernel data structures etc.).
Threading means splitting up a process into several (well :) threads, and

let them run on either one or more than one CPU. This is basically an

application-layer issue, in contrast to SMP which happens inside the

kernel. Having SMP available helps for performance in threads systems as

threads can be ran in parallel on several CPUs, but SMP is not strictly

necessary for a threaded system.
Many applications today use a threaded software architecture (over the

classical Unix "fork"ed processes), and so having some efficient threads

implementation is an important goal of the NetBSD project.
With the Scheduler Activations based work that Jason and Nathan made, this

is a very efficient implementation that can map N userland threads to M

kernel threads, and there is no need to have one kernel thread for each

userland thread, like some other systems (used to?) have, and which kills

performance for many threads.
With native threads now available in NetBSD-current, applications from

pkgsrc will readily pick it up upon rebuild, and things will be fixed over

the coming time.
For instructions on how to port existing applications and to use threads

in your own programs using the new libpthreads that come with NetBSD now,

see http://www.humanfactor.com/pthreads/.
(Thanks to Hubert Feyrer  for the detailed press

release.)
--

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         Multiarchitecture OS, no hype required.