(j3.2006) illusive exaflops

[Jerry Wagener]

The article was written by Peter Kogge of Notre Dame (but formerly of IBM Systems Division), who chaired an expert panel commissioned by DARPA to investigate what it wold take to build an exaflops computer that consumed less than 20MW and would fit in 500 conventional server racks. And with foreseeable technology that looks to be unattainable. One thought experiment they did that I thought was interesting was to reduce the transistor switching voltage from today's typical 1 volt to 0.5 volts, thereby reducing power consumption by a factor of four. The price one pays for that, however, is somewhat slower switching and, to a lesser extent, stability. Moving data fast enough is an even bigger challenge (but maybe optics can ride to the rescue here). Fascinating stuff.

    -Jerry

On Feb 22, 2011, at 7:59 PM, Van Snyder wrote:

> 
> On Mon, 2011-02-21 at 14:47 -0800, Jerry Wagener wrote:
>> In the 80's for instance, for most of the decade we tracked the
>> fastest computers in megaflops, and it was big news when the first
>> gigaflops computer appeared. As I recall in the late 90's we were
>> anticipating the amazing advent of the first teraflops computer. And
>> now, according to the article, the fastest computer is about 5
>> petaflops. So for the past 3 decades we've roughly, on-average,
>> doubled the top computing speed each year (10**6 to 10**15). That's
>> even faster than Moore's Law. Amazing. 
>> 
>> But, alas, the article points out that some tough physical limits are
>> raising their ugly heads which look like this era may be coming to an
>> end, and with it DARPA's hopes for an exaflops computer by 2015 may
>> not be realized. Though I'm reminded of the saying that somebody
>> saying something's impossible is usually interrupted by somebody doing
>> it. Anyway, for an old out-of-touch Fortran geezer it was an
>> interesting read.
> 
> At JPL last year, there was a talk by an IBM fellow from the University
> of Kansas (whose name I have forgotten).  He had a contract from DARPA
> to address the question of power consumption.  He looked at computing
> from the gate level, asking how many joules are required per operation.
> DARPA wants their exaflop computer to use less than 38 MW.  The result
> of the study is that with current technology or that foreseen for the
> reasonably near future, it can't be done for less than 60 MW.
> 
> 
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