🚀 go-pugleaf

In article <17500@obiwan.mips.COM> mark@mips.COM (Mark G. Johnson) writes:
.....
>Seems to me that backplanes (or, in general terms, processor-to-
>main-storage data trunks) are nearly pooped out.  At least for the
>kinds of air cooled, medium-priced computers that tend to have
>microprocessors for CPUs.
....
>And that's just for the very next generation of air cooled, medium
>priced CPU --- 60 VUP performance is eminently forseeable in the next
>6 to 24 months (schedule varies depending upon who you talk to :-).
>Soon thereafter it will be 1994, when you can buy 125-250 VUP micros
>for cheap, and when the few remaining software issues concerning
>32-way multiprocessors will be solved :-).

There's a issue of UNIX Review coming up a while off on something
like "fundamental systems technologies".  We (the editorial board, that is)
were discussing this issue, which might tentatively 3 articles, looking at
thetechnologies over the next few years:

1. CPUs (great! mips/flops are almost free)

2. Busses (oh, oh! we're in trouble trying to match the CPUs)

3. I/O (esp. disks) (well, now we're REALLY in trouble).

A particularly interesting issue about busses: MultiBus, and especially,
VMEBUS, happened about the same time as micros to which they were matched.
VMEBUS had enough headroom to remain adequate, even for a 20-VUPS machine
(albeit barely, as an I/O bus).  This was good, because it let people
leverage off many other people's controller development. (Remeber that
a VMEBUS is something like 40MB peak, 25MB sustained).

As Mark notes, the coming 100+ VUP micros aren't so forgiving.
1) In a balanced system, a single VMEBUS (with block-mode controllers,
appropriately interleaved/fifoed memory controllers, etc) is out of gas
for anything above a 20-25-VUPS system, for sure.

2) Maybe no one will expect to have a "standard" memory bus of any sort,
and instead, just connect up controllers to I/O adaptors.
This is sort of sad.

3) it is pretty easy to look ahead just a few years, to see how to build
systems in the 500-1000-VUPS range, which could fit in a deskside (large
deskside) package, if you wanted, assuming you could build a main
memory bus in the 750-1500MB/sec region......

4) Does anybody know of anything like that being proposed as a standard?
No? well, it looks like we're in for a lot more multiple-bus architectures...:-)
-- 
-john mashey	DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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