[Beowulf] Has anyone actually seen/used a cell system?

Jim Lux James.P.Lux at jpl.nasa.gov
Thu Sep 21 13:30:38 EDT 2006


At 03:32 PM 9/20/2006, John Leidel wrote:
>Uh oh... I see another HPL debate looming in the wings.  :-)
>Once again, we find ourselves debating how to measure synthetic 
>performance in order to quantitatively compare extremely disparate 
>architectures. The HPL test(s) fill a need.  However, my personal 
>belief is that we must simply wait until the machine is built and 
>decide based on /real/ workloads how it performs. The cell is 
>certainly an interesting, yet complex, approach to computing.   My 
>only fear is that we, as an industry, are not paying close attention 
>to our common strategic goal : Perform more science per unit 
>time.  So I pose a question, with the advent of such complex 
>machines, are we taking a step forward or in reverse?


But, science has been done with things like "attached array 
processors", notably things like the Floating Point Systems AP120B 
FFT box, some 30 years ago, so complexity, to get to a solution, 
isn't inherently steps in the wrong direction. (the original AP120 
was an integer array coprocessor, designed to do FFTs for "acoustic 
signal processing" with ARPA money.  The AP120B was apparently 
targeted to folks in oil, seismic processing I assume.  One might 
assert that this is grubby commerce and not science, though.)

Also, is the goal:
  perform more science per unit time
  OR
  perform more science per dollar
  OR
  some combination of these plus other factors.

   This gets into fascinating discussions about are you better of 
spending X dollars on computers that run at Y speed today, and 
computing for 3 years, or, invest the X dollars, wait 2 years, and 
spend >X dollars on computers that run at >Y*3 speed and compute for 1 years.

Personally, I like R.W.Hamming's statement: "The purpose of computing 
is insight, not numbers", so on that basis, since science is 
hopefully driven more by insight rather than raw crunching, computing 
sooner is better than computing later.


>Joe Landman wrote:
>>Craig Tierney wrote:
>>
>>>see it in the near future.  The key to winning the Roadrunner 
>>>proposal was to get HPL to run at over 1 PF (science be damned).  The Cell
>>
>>heh ...
>>
>>Maybe it is time to define a unit of measure.
>>
>>   1 HPL = 1 TF
>>
>>or something like that ...
>>
>>
>
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James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875 


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