A GPU-inspired soft processor for high-throughput acceleration

There is building interest in using FPGAs as accelerators for high-performance computing, but existing systems for programming them are so far inadequate. In this paper we propose a soft processor programming model and architecture inspired by graphics processing units (GPUs) that are well-matched to the strengths of FPGAs, namely highly-parallel and pipelinable computation. In particular, our soft processor architecture exploits multithreading and vector operations to supply a floating-point pipeline of 64 stages via hardware support for up to 256 concurrent thread contexts. The key new contributions of our architecture are mechanisms for managing threads and register files that maximize data-level and instruction-level parallelism while overcoming the challenges of port limitations of FPGA block memories, as well as memory and pipeline latency. Through simulation of a system that (i) supports AMD's CTM r5xx GPU ISA [1], and (ii) is realizable on an XtremeData XD1000 FPGA-based accelerator system, we demonstrate that our soft processor can achieve 100% utilization of the deeply-pipelined floating-point datapath.