Author: Robert Hyatt
Date: 19:44:00 07/12/03
Go up one level in this thread
On July 12, 2003 at 17:51:12, Vincent Diepeveen wrote: >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his hands on an outdated Sun machine with 2 processors.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. Compute the inverse of that matrix on your TERA. _THEN_ you will see the bandwidth problem when the entire array has to be used by the entire machine. NUMA dies. > >It's as i said busy now creating a 8TB database for weather predictions. Different application. Different math. "embarassingly parallel". > >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. Again, different machine. Different target application. Different math. The opterons won't touch the T90 for several reasons. For some applications, yes. But for some _important_ applications. No. Clusters are not the answer to _all_ questions. Neither is NUMA. That's why supercomputer companies like Fujitsu, Cray, NEC, etc build such machines. > >>>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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