[Beowulf] ARM cpu's and development boards and research

Vincent Diepeveen diep at xs4all.nl
Wed Nov 28 14:12:52 PST 2012

On Nov 28, 2012, at 10:47 PM, Prentice Bisbal wrote:

> On 11/28/2012 11:27 AM, Vincent Diepeveen wrote:
>> On Nov 28, 2012, at 4:30 PM, Prentice Bisbal wrote:
>>> On 11/27/2012 07:32 PM, Vincent Diepeveen wrote:
>>>> On Nov 28, 2012, at 12:17 AM, 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,
>>>>> 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.
>>>> For HPC the winning concept seems to be increasing corecount at  
>>>> manycores.
>>>> We also see how bluegene couldn't keep its concept - it's having  
>>>> what is it 18+ cores
>>>> now or so?
>>> It's not 18+. It's exactly 18 cores. And only 16 are used for  
>>> computation. One is used for operating system overhead, and the  
>>> other is a spare.
>>> This is exactly in keeping with the Blue Gene Concept, which is  
>>> using low-power processors to conserve energy connected to highly- 
>>> optimized interconnects to create a more balanced system.  'Low- 
>>> power' and 'low core-count' are not the same thing.
>> Here is what wiki says on the original concept: "Trading the speed  
>> of processors for lower power consumption. Blue Gene/L used low  
>> frequency and low power embedded PowerPC cores with floating point  
>> accelerators.While the performance of each chip was relatively  
>> low, the system could achieve better performance to energy ratio,  
>> for applications that could use larger numbers of nodes."
>> It's obvious this won't be the case in the future.
>> It means the future is big fat manycores eating a ton of power for  
>> each CPU.
>> Arguing then that each core is low power is not relevant - it's  
>> not the original concept of the CPU being low power and embedded
>> as you can see from the wikisayings.
> *Sigh*... Many lower-powered cores can still equal a low-powered  
> complete processors.

New hardware in general is faster than old hardware.

Regardless - it's big fat manycore CPU's/GPU's that eat massive power  
and which are not low powered processors,
with big fat fast interconnects eating also quite some power  
(relative seen) that dominate and will dominate, also for IBM.

No nothing low power cpu's with small simple network interconnects.

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