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Subject: Re: Cray

Author: Vincent Diepeveen

Date: 14:51:12 07/12/03

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On July 11, 2003 at 12:52:13, Robert Hyatt wrote:

>On July 10, 2003 at 23:18:30, Vincent Diepeveen wrote:
>
>>On July 10, 2003 at 16:36:50, Robert Hyatt wrote:
>>
>>>>You show up with a cray supercomputer and i may only bring something my hands
>>>>can carry :)
>>>
>>>Feel free to do so.  I'll take a T932 over _anything_ you can carry by
>>>hand, no questions asked.
>>
>>The Cray the NWO owned a bunch of years ago was replaced by the 1024 processor
>>TERAS machine in 2000.
>
>Please read what I wrote.  "over anything you can carry by hand..."
>
>I think that is pretty clear.  And you aren't going to carry a 1024 processor
>TERRA by hand.
>
>
>>
>>It now is upgraded to 1440 processors. That is a new machine with 416 processors
>>is added to it. Most jobs they found out at the TERAS were either up to 8 cpu's
>>or up to 32 cpu's.
>>
>>>>I'm not sure about the microprocessor designs, we can ask AMD and intel after
>>>>it. Apple doesn't produce microprocessors at all. They use IBM processors
>>>>nowadays and before IBM they used Motorola.
>>>
>>>Apple produces _machines_.  They do circuit layout and testing on a Cray.
>>
>>That's funny because i do not own a single apple product AFAIK. My sister does
>>though. That's typical however as she is a graphics artist and VJ and makes a
>>small chance to get our first female prime minister :)
>>
>>>>
>>>>However about the weather forecasting guess why the 1024 processor from december
>>>>2002 till end of gulfwar II was overloaded with weather guys :)
>>>>
>>>>It was like this. On average 400 cpu's got used up until december. Then suddenly
>>>>a dang at the machine. When i checked out which dudes prevented me from doing a
>>>>few tests, i knew it was going to be war soon.
>>>>
>>>>Weather guys LOVE memory. For them vector processing isn't so important as is a
>>>>huge memory.
>>>
>>>They are related.  Vector processing lets you _use_ "huge memory" efficiently.
>>
>>Yes put that in between "", see below.
>>
>>>>
>>>>I remember a weather guy some 7 years ago who as a selfemployed managed to lay
>>>>his hands on an outdated Sun machine with 2 processors. He was in the skies so
>>>>happy. I asked him then why he was so happy with those dusted cpu's and he
>>>>explained that he didn't care for the cpu's but for the 2 GB memory inside :)
>>>
>>>Cray's don't come with 2 gigs of memory.  The T90 typically has 16-32 gigs.
>>
>>that's funny because that poor Cray T916 which was replaced by the TERAS, it has
>>1 terabyte since 2000 already. It has soon nearly 2.
>
>Different machine.  You won't do this on your Terra:
>
>double x [1000][1000][1000];
>and then do anything useful with it.

that's less than 8GB!

that's indeed not useful for the TERAS.

Too small.

It's as i said busy now creating a 8TB database for weather predictions.

To use your way of representing that's a dataset of:

  double x [1024][1024][1024][1024];

Such 8GB arrays you can let 2 oxens handle even :)

350000 cpu hours come down to 350k gflops = 350 tflops = 0.35 petaflops

I guess for matrix multiplications they'll be using for the 8TB database
something like an approximation library, because a single matrix calculation
with the weather prediction database is just too slow as you need = 10^40
calculations for that which even is a bit much for the Earth machine to do :)

>That is the power of the Cray, to handle large arrays _and_ stomp through
>them impossibly quick without regard to NUMA issues.

That's why they're gonna use opterons and hypertransport in the future for
Crays.

>>The climate job that runs now at the TERAS needs around 350000 cpu hours and 10
>>terabyte of i/o, so 1 TB memory is more than welcome for it.
>>
>>When it would run on the old Cray T916 (strong oxens) that would take 150 years
>>it says.
>>
>>Best regards,
>>Vincent



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