Author: Robert Hyatt
Date: 21:06:26 07/12/03
Go up one level in this thread
On July 12, 2003 at 22:09:08, Jeremiah Penery wrote: >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. This sounds like the "story of chicken little". Cray is replacing the alphas with opterons in the T3 product line. Vincent hears that. He races around "Cray is only using opterons in new machines." Of course, that misses the vector products from Cray/NEC, including the X1 released last year (which you mentioned). But, remember. "the sky is falling. the sky is falling." "because I said so". "because a piece of it hit me so I saw it." that _does_ make reasonable conversations impossible with him. mangled definitions of common terms (IE RISC -> no more than one instruction per clock cycle, simple CPU design, etc., MPI/OpenMP -> protocols, rather than APIs, etc.) If there is no common, accepted definition of technical terms, technical discussions revert to noise.
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