Author: Jeremiah Penery
Date: 19:09:08 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: > >>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. How long will that multiplication take on the TERAS? Probably a long time. >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 350 TFLOPs can take about a minute on the Earth Simulator, given only 16% efficiency. Weather simulation achieves very good efficiency on the Earth Simulator (that's its primary purpose), so it's likely to be even faster. >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 :) I don't know where you get 10^40 from, but you still completely don't understand vector calculation. >>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. No, they're not. Cray is building *one* Opteron machine for Sandia Labs. Go look up their future plans, involving X1 and X2 machines, which are all *vector* machines.
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