[Beowulf] Pony: not yours.

Mark Hahn hahn at mcmaster.ca
Thu May 16 08:45:21 PDT 2013

>> I found it unilluminating, actually.  don't we all know about power issues?
> Know? Yes. To this extent? Maybe not.

OK, I can see that.  to me, power is similar to a number of other issues, 
which provide extreme limits to scaling.  (power, reliability, net,
perhaps even storage and software complexity).  from a CS background,
these all have distressing O()-type complexity, so each is clearly
a hard limit at some scale, given some level of technology.

maybe I'm just more pessimistic ;)

I guess I did think the flops power versus even on-chip communication thing
was interesting.  but isn't the lesson to optimize for dataflow *and*
sometimes perform redundant computations?

>>> forward and with a 20 Mw power budget, an exascale machine's network
>> would
>>> consume all the power leaving nothing for computation.
>> well, that sounds absurd - were they assuming a full-bisection fat tree of
>> older (hotter, lower fanout) generation interconnect?
> Even dragonfly topologies (high-radix routers with low hop count) and a
> bandwidth taper of 1/2 given current power consumption levels will exceed
> 20 Mw.

anyone have an url on this topic?  fundamentally, I've always reasoned that 
since we exist in 3d, our networks need to be a 3d lattice at scale.
fighting power (flops, comm) seems like a noble, *engineering* fight,
but fighting our existence's dimensionality is silly...

yes, I would like to demo your new blackhole-based interconnect! ;)

regards, mark hahn.

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