Perf/W, the official metric of slow but efficient processors. How many times must we go down this road? Let's see this sucker train AlexNet...
Wearing my CMU hat for a moment (but keeping in mind Google's paying me this year): Google's always been cautious about the balance of speed and efficiency, out of concerns about programmer productivity, parallelization, and generality. See, for example, Urs's article in response to my and a few other people's crazy-academic research on using "Wimpy" nodes: http://static.googleusercontent.com/media/research.google.co…
For if it were delivering performance on par with a $1000 Maxwell class GPU, why wouldn't you guys crow about it? That would be a really big deal wouldn't it? TitanX for 20W? That'd be awesome.
And having suffered through multiple pitches for us to buy various FPGA and boutique processors, I have yet to see someone who produced perf per watt numbers first, subsequently produce an impressive performance number. In fact, it took nearly yelling at one vendor for them to finally admit perf was abysmal.
Finally, training does not equal inference. Training requires strong scaling, but inference need only weak scale. So I suspect that Urs had to bite his tongue and buy a bunch of gpus for training networks.
Am I missing something?