Bill Broadley wrote: > Joe Landman wrote: >> Hi David >> >> David Mathog wrote: >>> Although the folks now using CUDA are likely most interested in crunch >>> per unit time (time efficiency), perhaps some of you have measurements >>> and can comment on the energy efficiency of GPU vs. CPU computing? That >>> is, which uses the fewest kilowatts per unit of computation. My guess >> Using theoretical rather than "actual" performance, unless you get the >> same code doing the same computation on both units: >> >> 1 GPU ~ 960 GFLOP single precision, ~100 GFLOP double precision @ 160W > > That sounds like the Nvidia flavor GPU, granted nvidia does seem to have a > larger lead over ATI for such use... at least till OpenCL gains more > popularity. Nvidia's double precision rate is approximately 1/12th the single > their precision rate. ATI's is around 1/5th, which results in around 240 > GFlops. >
Where did you get the 1/12th number for NVIDIA? For each streaming multiprocessor (SM) has 1 single precision FPU per thread (8 threads per SM), but only 1 double precision FPU on the SM. So that ratio would be 1/8. I have demonstrated this ratio on a simple code that required little to no memory transfers. ATI still provides more dp flops. Craig > So in both cases you get a pretty hefty jump if your application is single > precision friendly. > > Of course such performance numbers are extremely application specific. I've > seen performance increases published that are a good bit better (and worse) > than the GFlop numbers would indicate. If you go to http://arxiv.org and type > CUDA in as a search word there are 10 ish papers that talk about various uses. > > So basically it depends, either AMD, Intel, Nvidia, or ATI wins depending on > your application. Of course there's other power efficient competition at > well, atom, via nano[1], sci cortex (mips), bluegene, and the latest > implmentation the PowerXCell 8i which is available in the QS22. > > Assuming you have source code, and parallel friendly applications there's > quite a few options available. Ideally future benchmarks would include power, > maybe add it as a requirement for future Spec benchmark submissions. > > [1] http://www.theinquirer.net/inquirer/news/1137366/dell-via-nano-servers > > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf > -- Craig Tierney (craig.tier...@noaa.gov) _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
