On Fri, 11 Mar 2005 12:31:40 +0000
"Bruce O'Neel" <edoneel@sdf.lonestar.org> wrote:

> Hi,
> 
> Thanks for the answer.  So it sounds like one can then buy the dual
> processor card and a 9600 uniprocessor and just swap them, right?
> 
> Next stupid question.  The 7300-8600 systems all seem to have
> interchangeable processors right?  If so, does that mean that one
> could stick a 9600 dual processor board in say a 7300?  Or would it
> fit but then just smoke the power supply.
> 
> And no, I wasn't expecting MacOS to run on the resulting system :-)

Why not? MacOS recognized MP cards as far back as 8.6. Their MP API was
actually quite mature, even as early as the mid-90's. If the G3 debacle
hadn't occured, without a doubt Apple would have been quite agressive
regarding MP.

However, regarding NetBSD and speaking as someone that uses an MP card
daily in a 7300, there are several factors that suggest you would be
better off investing in a SP G3 or higher upgrade card of equal MHz to
the sum of the MP card you're considering. Interrupts are handled by one
processor only and the kernel uses a "big lock" model for resource
sharing in MP kernels. Networking is actually a tad slower with MP, and
when building single object files, UP beats MP. Only when two or more
object files are being built does MP go faster. If I do a single job
build while in an MP kernel, other user actions remain responsive, as
much as one would expect with a SP kernel operating at the single CPU
speed (the other CPU being occupied). For pure performance, though, I'll
take a single 300MHz G3 upgrade card over a DP 180MHz 604e card (and I'm
a big fan of MP because slower CPUs are cheaper than faster ones and MP
horsepower can be done cheap). I just use my DP card because I bought it
when it looked like Apple was buying Be and I'd already run BeOS on my
7600 (BeOS had fantastic MP capabilities). I use my G3 upgrade card
elsewhere (a MacOS based router), but NetBSD 1.6.2 was quite snappy with
it.

tim