Vincent, I'm missing something in the arithmetic. "3 nodes of quadcore" is 12 cores? delivering 100 "GFlops" would require something like 8 GHz? So perhaps you mean, 3 nodes of dual socket, quadcore CPU (24 cores) at 4GHz? And you can get that for $1500? Thanks, Peter
On Nov 9, 2007 11:44 AM, Vincent Diepeveen <[EMAIL PROTECTED]> wrote: > Larry, all what you write is very interesting and of course i hope > for you your product line gets a big succes. > Just like IBM's blue gene, the major expertise of your product line > is that it is only interesting to governments who need major amounts of > crunching power (the other conditions left aside such as no big RAM > requirements as that usually means you need good branch prediction > and so on), > and who have million dollar budgets, and probably have a program > lying around where this hardware can get used for. > > The price of a box with say 100 "1 gflop" cpu's, delivering in total > 100 gflop isn't gonna be $1500 i guess, whereas for 1500$ one can > build hands down > 3 nodes with a quadcore, delivering not only *more* than 100 gflop, > but also capable of doing other software than just crunching; it's > also possible to put > a lot of RAM inside and it's also possible to run software that's > making a lot of use from the branch predictor. > > For sure you're not qualifying for a $2500 setup, and with those > freak qualifications you qualify bigtime for this mailing list of > course :) > > > On Nov 9, 2007, at 3:42 PM, Larry Stewart wrote: > > > Robert G. Brown wrote: > > > >> On Thu, 8 Nov 2007, Jim Lux wrote: > >> > >>> In general, a N GHz processor will be poorer in a flops/Watt > >>> sense than a 2N GHz processor. > >> > > Well that just isn't so. It seems pretty clear from IBMs BlueGene/ > > L, as well as the SiCortex processors, that the > > opposite is true. The new Green 500 list is brand new, and there's > > not much on it yet, but the BG/L is delivering 190MF/Watt > > on HPL, whereas the machines made out of Intel and AMD chips are > > half that at best. > > > >>> > >>> The power draw is a combination of a fixed load plus a frequency > >>> dependent load, so for the SAME processor, running it at N/2 GHz > >>> consumes more than 50% of the power of running it at N GHz. > >> > > This probably IS true, but high performance cores have a lot more > > logic in them to try to achieve performance: out of order > > execution, complex branch prediction, register renaming, etc. etc. > > A slower core can be a lot simpler with the same silicon process, > > so a decent lower-clock design will be more power efficient than a > > fast clock design. > > > >>> > >>> If you go to a faster processor design, the frequency dependent > >>> load gets smaller (smaller feature sizes= smaller capacitance to > >>> charge and discharge on each transition). The core voltage is > >>> also usually smaller on higher speed processors, which also > >>> reduces the power dissipation (smaller number of joules to change > >>> the voltage from zero to one or vice versa). So, in general, a > >>> 2N GHz processor consumes less than twice the power of a N GHz > >>> processor. > >> > > The flaw in this argument is that a slower clock design can use the > > same small transistors and the same current state of the art > > processes and it will use many fewer transistors to get its work > > done, thus using very much less power. Our 1 GF core is 600 > > milliwatts, for example. > > Even after adding all the non-core stuff - caches, memory > > controllers, interconnect, main memory, and all overhead, it is > > still around 3 watts per GF. > > > >> > >> In ADDITION to this is the fact that the processor has to live in a > >> house of some sort, and the house itself adds per processor overhead. > >> This overhead is significant -- typically a minimum of 10-20 W, > >> sometimes as much as 30-40 (depending on how many disks you have, how > > > > This factor does not scale this way! With low power processors, > > you can pack them together, without the endless support chips, you > > can use low power inter-chip signalling, you can use high > > efficiency power supplies with their economies of scale. If you > > look inside > > a PC there are two blocks doing useful work - memory and CPUs, and > > a whole board full of useless crap. Look inside a machine designed > > to be a cluster and there should be nothing there but cpus and memory. > > > > > > -- > > -Larry / Sector IX > > > > _______________________________________________ > > Beowulf mailing list, Beowulf@beowulf.org > > To change your subscription (digest mode or unsubscribe) visit > > http://www.beowulf.org/mailman/listinfo/beowulf > > > > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf > _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
