On Wed, Jan 31, 2018 at 09:59:28AM -0500, David Collier-Brown via talk wrote:

There are two different cases to consider when doing data centers:

 * uniprocessors for individual tasks or trivially parallelizable ones
 * multiprocessors for things that aren't parallelizable

Anybody can provide the first. The second is harder.

Mips had three MMUs, one of which was for each of the above cases and one
was a trivial one for embedded, so 32-CPU Mips machines were available.

IBM and Sun spent lots of money designing backplanes that could support >=
32 sockets: Sun when so far as to license a Cray design when their in-house
scheme failed to scale.

Until and unless chip vendors spend significant time and money on MMUs and
backplanes, they won't have an offering in the second case, and will have
chosen to limit themselves to a large but limited role in the datacentre.

Well at least for ARM, you have qualcomm and cavium offering 48 core
CPUs with two socket, so 96 cores in one machine.  That's not a bad start.

Now as to wether you can actually buy any of those stupid boxes unless
you are a clour provider or google or something, who knows.

Well it seems maybe you actually can:

https://www.avantek.co.uk/store/avantek-48-core-cavium-thunderx-arm-server-r270-t64.html
https://www.avantek.co.uk/store/avantek-48-core-cavium-thunderx-arm-server-r150-t62.html

Yes: it's way easier if the interconnects are inside the chip!

I notice that the T4 and T5 offerings from Sun concentrated on doing the most you could in one chunk of silicon, and internally those devices greatly resembled a "radial" mainframe from the IBM/Honeywell/Sperry/CDC era.

What goes around, comes around (;-))

--dave

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain