[geeks] Re: Super Sun3

[Joshua D. Boyd]

On Thu, 17 May 2001, Michael Thompson wrote:

> >I was surfing ebay, and I saw this Dual MC68040 VME Single Board Computers
> >(http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1236413911).
> >
> >The following occured to me.  Many Sun3 owners run NetBSD, OpenBSD, or
> >linux instead of SunOS.  So, one could take 4 or these boards, cram them
> >into a Sun3/160 chassis, and run linux SMP with Mosix patch on them.
> >Thus, making a Super Sun3. 
> <snip>
> 
> VMEbus doesn't support cache coherency so SMP across the backplane won't
> work. There are other possibilities though. You could run SMP on each board
> and then cluster the boards with Beowulf software. You could get 42 CPUs in
> a 19" rack using commercial 21 slot VMEbus subracks. You could also use
> BusNet to run TCP/IP across the VMEbus backplane and get about 20 MB/s
> between boards.

I was assuming that the caches wouldn't be coherent over the bus.  That's
why I mentioned Mosix.  Mosix takes several machines on a network and
treats them as one.  So, if I have 4 dual processor machines with 256s
megs of ram, the mosix will let me write programs as if they are running
on a single 8 processor machine with a gig of ram.  This is a great way to
build linux supercomputers.  I don't know how well it deals with
optimizing memory locations to minimize memory access latencies, but it is
still cool none the less.

--
Joshua Boyd