[Beowulf] ARM cpu's and development boards and research
eugen at leitl.org
Tue Nov 27 23:40:47 PST 2012
On Tue, Nov 27, 2012 at 06:17:55PM -0500, Prentice Bisbal wrote:
> On 11/27/2012 03:37 PM, Douglas Eadline wrote:
> >> My interest in Arm has been the flip side of balancing flops to network
> >> bandwidth. A standard dual socket (AMD or Intel) can trivially saturate
> >> GigE. One option for improving the flops/network balance is to add
> >> network bandwidth with Infiniband. Another is a slower, cheaper, cooler
> >> CPU and GigE.
> > applause.
> I applaud that applause.
> What Bill has just described is known as an "Amdahl-balanced system",
> and is the design philosophy between the IBM Blue Genes and also
> SiCortex. In my opinion, this is the future of HPC. Use lower power,
The laws of the universe agree with your opinion. A provably optimal
classical computing configuration requires a close packing of the nodes
so that they're within each other light cones to minimize communication
latency. A sea of nodes on a mesh is will approach that asymptotically,
by shrinking the grain size until the units of memory and computation
is identical. Notice that you don't need a global clock, as local
communication can be asynchronous, and in general a locally weakly
coupled system of oscillators will synchronize soon after bootup, until
they beat in unison.
Your problem is mapped to a virtual circuit trace, laid out in
a 3d volume, with a volume refresh rate commensurable with
geometry of the light cone, which has a physical limit of about ~nm.
I also hope that spintronics, both for storage (MRAM) and computation
will reduce the power envelope, and also increase reliability (e.g.
spintronics is effectively immune to radiation).
> slower processors, and then try to improve network performance to reduce
> the cost of scaling out. Essentially, you want the processors to be
> *just* fast enough to keep ahead of the networking and memory, but no
> faster to optimize energy savings.
> The Blue Genes do this incredibly well, so did SiCortex, and Seamicro
> appears to be doing this really well, too, based on all the press
> they've been getting. With the DARPA Exascale report saying we can't get
> to Exascale with current power consumption profiles, you can bet this
> will be a hot area of research over the next few years.
> Okay. I'm done listening to myself type.
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