Adding Symmetric Multiprocessing to Amiga UNI

[Scott Hess]

In article <20708 at hydra.gatech.EDU> ken at dali.gatech.edu (Ken Seefried iii) writes:
   Keith Packard (the X Performance Man at MIT) has indicated that the 
   best way to speed up an X server is to put it on a fast processer with
   good memory bandwidth and direct access to the frame buffer.  The
   worst way is to try and stick it at arms length on some form of
   co-processor.  Bottom line seems to be that if your concern is a fast
   X server, leave it on the '040.  If you offload disk, net and serial
   traffic from the main CPU, I think you'll see a big win all the way
   around.  'Course, I'd want to get some empirical data before I bet the
   farm on it...

doug at ctc.contel.com (Doug Whitehead) writes:
   My embellishment: 
   Hey why not use the 68030 exclusively for an X server!  Some folks 
   pay the cost of an AmigaUX just for an X server.  This would be a KILLER
   X window system!!!

crs at convex.cl.msu.edu (Charles Severance (System Manager)) writes:
   Just another idea for use of the spare '030 in the Amiga.  There is a lot
   of CPU wasted to run the bit-mapped graphics display when running
   X-Windows, open-look, etc.  The '030 could run dedicated display
   software and be sent messages about what is to be displayed.  
   (almost like having the '030 acting like an X-terminal in the same 
   box.) 

   Then the '040 could do the actual work.

I suspect that the best solution, that is, if you're considering this,
is to put the X server on the _040_.  Yes, I know, blasphemy.  But,
when it comes right down to it, an 030 running application code only
(no X server, in other words) could probably keep the 040 running X
fairly busy.  Put io processing and everything on the '040, too, and
the '030 can run unconstrained.  Look at the NextDimension (and many
other graphics boards for other computers) - an i860 is faster than
an '040 for most stuff (though I'm sure it wouldn't run Unix so
well :-).  Most applications written for graphical environments
(X is, arguably, a graphical environment) spend more time drawing
graphics than doing calculations.  Exceptions?  Mandelbrot sets,
ray tracing, etc - but those would probably be better run in the
background without any window system running (sigh, an '040 and an
'030 would be heaven).  For those types of programs, the 040 wouldn't
be able to keep the 030 running X busy (X is very bitmap-oriented,
so would fly through the _display_ of the bitmaps resulting from
the calculations, while the calculations wouldn't be helped at all
by X).

But gosh, the '040 running X alone, 030 running clients would
be _slick_.  Put the windowmanager on the 040 side (so it's close
to those events), and you've got yourself a great machine to
sell X with ("now, see how the windows fly across the screen
when you move them).  From the way it sounds, though, it would
probably be better to get the Amiga custom chips working the X.

I guess maybe you could do like some of us were thinking of on the
NeXTs - we'd get our upgrade board, and leave the current system
board in (well, with a couple modified traces).  Then, you'd have
two completely seperate motherboards, one with an '040, one with
an '030, though you'd not be able to run two monitors off of it.
How to connect them?  Thinwire ethernet . . . While I'll admit
that this is not the best solution, it's simple.  I don't know
if that would work for an Amiga with a coprocessor, unless the
coprocessor ignored system memory - something I would be surprised
at (would the boards be regular backplane boards or special slot
boards?  Makes a difference . . .).  You never know, though . . .
sounds fun either way . . . .
--
scott hess                      scott at gac.edu
Independent NeXT Developer	GAC Undergrad
<I still speak for nobody>
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