About Multiprocessing

Joel Sherrill <joel@OARcorp.com> joel.sherrill at OARcorp.com
Tue Dec 20 13:27:38 UTC 2005

Ralf Corsepius wrote:
> On Tue, 2005-12-20 at 20:11 +1100, Angelo Fraietta wrote:
>>there are over 40 CPUs (or rather BSPs) that RTEMS SUPPORTS
> ... but only 3 of these BSPs claim to support multiprocessing:
> m68k/mvme147s, m68k/mvme136, powerpc/psim :)
> i.e. multiprocessing for all cpus but the m68k and powerpc, probably has
> never been tested at all ;)

It was tested on the i960 and i386 as well but the BSPs involved have
been removed.  I also did some testing on a modified version of the 
sparc sis simulator but the hacks to the memory part of the simulator to 
get it to map UNIX shared memory were too ugly to keep.

The largest system I personally ever used was a 5 CPU system with an 
i960, 2 m68020's, and 2 i386's.

In any MP or distributed system, the issue is not as much how many nodes 
are supportable by the OS or comms layer, it is how effectively your 
application can actually use them.  With 16, you are saying your 
application is doing real work when it is split into 16 pieces, working 
a little, then communicating a little.

> Ralf

Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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