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From: nv90-mho@dront.nada.kth.se (Magnus Holmberg)
Newsgroups: comp.unix.amiga
Subject: Re: Adding Symmetric Multiprocessing to Amiga UNI
Message-ID: <1991Jan31.154251.16107@nada.kth.se>
Date: 31 Jan 91 15:42:51 GMT
References: <994@swrinde.nde.swri.edu> > <20708@hydra.gatech.EDU> <SCOTT.91Jan29193042@texnext.gac.edu> <1991Jan30.181208.1256@convex.com>
Organization: Royal Institute of Technology, Stockholm, Sweden
Lines: 44

In article <1991Jan30.181208.1256@convex.com> swarren@convex.com (Steve Warren) writes:
>In article <SCOTT.91Jan29193042@texnext.gac.edu> scott@texnext.gac.edu (Scott Hess) writes:
>                           [...]
>>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
>
                           [...]
>
>Either processor could write to memory physically located next to the other
>processor, but the other processor would of course be blocked from any
>memory accesses until that bus was released.  In other words, as long as
>the '040 is operating on coprocessor memory and the '030 is operating out
>of motherboard memory, they can both run at full speed simultaneously.  As
>soon as one processor crosses over into the other's memory, only one
>processor can access memory at a time (which may not hurt the '040 performance
>as much, with its larger cache, but it would slow the '030 down
>significantly).
>
			[...]
>
>On the other hand, by putting the X-server on the '030 you would still have
>a 32-bit port into the display memory.  The '030 would not perform as well
>as the '040 but it would still do quite well.  And the '040 would not be
>stalled very often because it would tend to work out of the coprocessor
>memory whenever possible.
>
			[...]
	
	I'm not very good at hardware (esp. w/ the 3000). It seems
	to me, though, that since the '040 wouldn't need to access 
	Chipmem much, in a setup like this, it might be possible to
	run it on the same 'half-cycle' as the PAD. That way, the
	CPU's wouldn't have to lock eachother out of the Fastmem-bus.

	(Please, correct me, if the processor isn't running at every 
	other cycle, anymore, in the 3000. I _said_ I didn't know 
	much about hardware...)


		    -MH