FlexCL: An analytical performance model for OpenCL workloads on flexible FPGAs

The recent adoption of OpenCL programming model by FPGA vendors has realized the function portability of OpenCL workloads on FPGA. However, the poor performance portability prevents its wide adoption. To harness the power of FPGAs using OpenCL programming model, it is advantageous to design an analytical performance model to estimate the performance of OpenCL workloads on FPGAs and provide insights into the performance bottlenecks of OpenCL model on FPGA architecture. To this end, this paper presents FlexCL, an analytical performance model for OpenCL workloads on flexible FPGAs. FlexCL estimates the overall performance by tightly coupling the off-chip global memory and on-chip computation models based on the communication mode. Experiments demonstrate that with respect to RTL-based implementation, the average of absolute error of FlexCL is 9.5% and 8.7% for the Rodinia and PolyBench suite, respectively. Moreover, FlexCL enables rapid exploration of the design space within seconds instead of hours or days.