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It is surprising the paper makes no comparisons with GPUs. So I will do it. For starters it looks like they are talking about integer operations (I only skimme
by mrb 10y ago
It is surprising the paper makes no comparisons with GPUs. So I will do it.
For starters it looks like they are talking about integer operations (I only skimmed the paper and it mentions an ALU, not an FPU), whereas my GPU numbers below are single precision floating point numbers. So it is apples vs oranges.
So, a modern 14-16nm GPU like the Tesla P100 or RX 480 does about 5 to 10 trillion ops/sec at 200-300 W, and approximately 30 pJ/op. So GPUs are about 5x less power efficient. The paper authors did a good job. However GPUs are not optimized for absolute power efficiency, but mostly for performance per $.
- frozenport 10y agoCursory Google search shows Pascal GPUs at 10pJ/op for double precision (these guys did int, which should be 10x faster)[1,2] [1] http://wccftech.com/nvidia-pascal-volta-gpus-sc15/ http://wccftech.com/nvidia-pascal-volta-gpus-sc15/ [2] http://prism.sejong.ac.kr/download/PRISM3_paper/PRISM_Ajaykumar_Kannan_presentation_final.pdf http://prism.sejong.ac.kr/download/PRISM3_paper/PRISM_Ajayku...
- duckingtest 10y ago(Dynamic) Power consumption goes up with square of voltage, so a comparison with a gpu's max power efficiency point (almost certainly underclocked and undervolted) could change the comparison significantly.
- stcredzero 10y agoPower consumption goes up with square of voltage This needs to become common knowledge amongst nerds and tech types.
- theparanoid 10y agoIt was more widely known, when every geek overclocked; no more.
- stcredzero 10y agoI was underclocking when everyone else was overclocking. Because I wanted quiet!
- mrb 10y agoYou are very right. I should have mentioned it in my comment. Back when I was mining bitcoins on AMD GPUs, undervolting and underclocking would easily double or triple the power efficiency.
- jacquesm 10y agoAnother big difference is that most GPU architectures are multi-lane SIMD (so single instructions acting on multiple data but multiple sets of those) whereas the linked architure is MIMD. In simpler terms: these processors all execute independent code whereas a GPU tends to have multiple cores but a (sometimes much) smaller number of threads of execution.
- amelius 10y agoAlso important is the memory bandwidth. You can do all the TFLOPs you want, but if you can't access the data fast enough, then there's a bottleneck.