FEM: A Step Towards a Common Memory Layout for FPGA Based Accelerators

FPGA devices are mostly utilized for customized application designs with heavily pipelined and aggressively parallel computations. However, little focus is normally given to the FPGA memory organizations to efficiently use the data fetched into the FPGA. This work presents a Front End Memory (FEM) layout based on BRAMs and Distributed RAM for FPGA-based accelerators. The presented memory layout serves as a template for various data organizations which is in fact a step towards the standardization of a methodology for FPGA based memory management inside an accelerator. We present example application kernels implemented as specializations of the template memory layout. Further, the presented layout can be used for Spatially Mapped-Shared Memory multi-kernel applications targeting FPGAs. This fact is evaluated by mapping two applications, an Acoustic Wave Equation code and an N-Body method, to three multi-kernel execution models on a Virtex-4 Lx200 device. The results show that the shared memory model for Acoustic Wave Equation code outperforms the local and runtime reconfigured models by 1.3–1.5x, respectively. For the N-Body method the shared model is slightly more efficient with a small number of bodies, but for larger systems the runtime reconfigured model shows a 3x speedup over the other two models.