Improving reconfiguration speed for dynamic circuit specialization using placement constraints

Dynamic Circuit Specialization (DCS) is an optimization technique used for implementing a parameterized application on an FPGA. The application is said to be parameterized when some of its inputs, called parameters, are infrequently changing compared to the other inputs. Instead of implementing these parameter inputs as regular inputs, in the DCS approach these inputs are implemented as constants and the design is optimized for these constants. When the parameter values change, the design is re-optimized for the new constant values by reconfiguring the FPGA. It has been investigated that run-time reconfiguration speed is the limiting factor of the DCS implementations on Xilinx FPGAs. We propose an idea to constrain the design´s placement and use the custom Xilinx HWICAP driver to improve reconfiguration speed at the cost of a small reduction in design performance. We use Xilinx Virtex-5 and Zynq-SoC as experimental platforms and we have used an 8-bit FIR filter with different tap configurations as our parameterized design whose filter coefficient values are infrequently changing inputs. A drastic improvement in the reconfiguration speed with a factor of 14 is achieved with only a ≈ 6% decrease in performance.