[HH] Adapteva's Epiphany

[Tom Metro]

Tom Metro wrote:
> It's not so clear to me what the compelling applications are for this.
> At "only" 1 GHz per CPU I don't think "supercomputer" is a compelling
> option.

High density, low power data center servers is another possibility, like
HP's "Redstone" servers:

http://www.theregister.co.uk/2011/11/01/hp_redstone_calxeda_servers/

  ...server cluster that makes use of the EnergyCore ARM RISC server
  chip just announced by upstart Calxeda.

  The hyperscale server effort is known as Project Moonshot, and the
  first server platform to be created under the project is known as
  Redstone...

  The ECX-1000 processors that are the first in the EnergyCore products
  are 32-bit chips that will come in two-core and four-core variants.

  They include memory, I/O, and storage controllers and an embedded
  Layer 2 switch fabric on the chip, which means you can just wire a 4GB
  DDR3 memory stick to one, slap on some I/O ports, plug these babies
  into a passive backplane, and you have interconnected server nodes
  that take the place of rack servers and top-of-rack switches.

  HP can cram three rows of these ARM boards, with six per row, for a
  total of 72 server nodes, in a half-width 2U slot, like this [see
  photo: http://regmedia.co.uk/2011/10/31/hp_redstone_server_tray.jpg ]

  ...you can put four of these trays in the chassis...That gives you 288
  server nodes in a 4U rack space, or 72 servers per rack unit.

  A more traditional x86-based cluster doing the same amount of work
  would only require 400 two-socket Xeon servers, but it would take up
  10 racks of space, have 1,600 cables, burn 91 kilowatts, and cost
  $3.3m. The big, big caveat is, of course, that you need a workload
  that can scale well on a modestly clocked (1.1GHz or 1.4GHz),
  four-core server chip that only thinks in 32-bits and only has 4GB of
  memory.


A blurb on this in Technology Review (where I first heard of it) says
"Calxeda...claims that its servers draw five watts when operating and
only half a watt when idle..." That's for a 4-core chip I presume (the
TR article doesn't specify, but I assume both articles are talking about
the same chips; and I assume by "server" they meant processor, because
the latter part of the sentence compares it to a "conventional server
processor that draws 160 watts when operating")), so the Epiphany beats
it if they can do 16-cores at 2 watts.

 -Tom