Energy efficiency of FPGA vs GPU vs CPU

This survey paper published in ACM Computing Surveys 2015 compares GPU with FPGA and CPU on energy efficiency metric. Most papers reviewed in the survey report that FPGA is more energy efficient than GPU, which, in turn, is more energy efficient than CPU.  

https://www.academia.edu/6644474/A_Survey_of_Methods_For_Analyzing_and_Improving_GPU_Energy_Efficiency

On Wed, 10 Jun 2015 12:40:41 -0700, computerarchitect wrote:

> This survey paper published in ACM Computing Surveys 2015 compares GPU
> with FPGA and CPU on energy efficiency metric. Most papers reviewed in
> the survey report that FPGA is more energy efficient than GPU, which, in
> turn, is more energy efficient than CPU.
> 
> https://www.academia.edu/6644474/
A_Survey_of_Methods_For_Analyzing_and_Improving_GPU_Energy_Efficiency

For one specific use, which is not the use that either GPUs or FPGAs were 
designed.

(Of course, it is, theoretically, the use for which CPUs were designed, 
and that's the one that sucks the worst -- go figure).

I did not read the paper.  Did it say anything about the ease of 
programming for GPUs vs. FPGA in the applications they were looking at?  
In my (limited) experience with DSP vs. FPGA tradeoffs for video 
application, the ultimate performance limit was memory bandwidth -- did 
this paper address inter-processor communications and memory issues, or 
was it just doing some artificial test like Dhrystones or MFLOP/Joule or 
something?

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com