Looking for point to compare SA and 1:1 threading model

[Jim Whitehead II <jnwhiteh%gmail.com@localhost>]

I am current in the process of researching the effect of various
threading models on programs that are structured in the OCCAM.  In
particular I am looking to make a comparison of scheduler activations
versus a 1:1 threading model for a very specific class of programs.
Obviously FreeBSD and NetBSD both implemented some form of scheduler
activations in the 90s, but both abandoned the threading model in
favor of the current 1:1 model.

I am looking to find a point in the NetBSD version history where I can
make a fair comparison between the two models.  In an effort to avoid
causing a debate regarding the advantages of disadvantages of each
(something that I see has been exhaustive on this list alone), I'm
wondering if anyone can provide help with the following questions:

1. Did the SA system in NetBSD ever get multiple CPU support [1] for
threaded applications?
2. How is the kern.no_sa_support option implemented?  Specifically, is
there a large amount of overhead associated that will bias a
comparison between having the option on and off?
3. Is there any point in the SCM history, or released versions that
would be appropriate for such a comparison?

I am aware that there are issues with the optimization of the various
libpthread implementations, but I didn't see a clear discussion of
where that ended up.  Were there ever improvements to that library, or
was it just lifted out of the system.

Anyone who is more familiar with the system and willing to discuss in
detail, please feel free to speak up!

- Jim

[1]: 
http://kerneltrap.org/index.php?q=mailarchive/netbsd-tech-kern/2003/7/10/280383