An Evaluation of Selective Depipelining for FPGA-Based Energy-Reducing Irregular Code Coprocessors

Jack Sampson, Manish Arora, Nathan Goulding-Hotta, Ganesh Venkatesh, Jonathan Babb, Vikram Bhatt, Steven Swanson, Michael Bedford Taylor
2011 2011 21st International Conference on Field Programmable Logic and Applications  
As the complexity of FPGA-based systems scales, the importance of efficiently handling irregular code increases. Recent work has proposed Irregular Code Energy Reducers (ICERs), a high-level synthesis approach for FPGAs that offers significant energy reduction for irregular code compared to a soft core processor. ICERs target the hot-spots of programs, and are seamlessly connected via a shared L1 cache with a soft processor that executes the cold code. This paper evaluates the application of
more » ... selective depipelining (SDP) technique to ICERs, which greatly reduces both the execution time and energy of irregular computations. SDP enables irregular computations to be expressed as large, fast, low-power combinational blocks. SDP maintains high memory bandwidth by scheduling the many potentially dependent memory operations within these blocks onto a high-frequency, highly-multiplexed coherent memory while scheduling combinational operations at a much lower frequency. SDP is a key enabler for improving the execution properties of irregular computations that are difficult to parallelize. We show that applying SDP to ICERs reduces energy-delay by 2.62× relative to ICERs. ICERs with SDP are up to 2.38× faster than a soft core processor and reduce energy consumption by up to 15.83× for a variety of irregular applications.
doi:10.1109/fpl.2011.16 dblp:conf/fpl/SampsonAGVBBST11 fatcat:jegt624lxrehdorxjdugio2qku