Exploring Shared Virtual Memory for FPGA Accelerators with a Configurable IOMMU

A key enabler for the ever-increasing adoption of FPGA accelerators is the availability of frameworks allowing for the seamless coupling to general-purpose host processors. Embedded FPGA+CPU systems still heavily rely on copy-based host-to-accelerator communication, which complicates application development. In this paper, we present a hardware/software framework for enabling transparent, shared virtual memory for FPGA accelerators in embedded SoCs. It can use a hard-macro IOMMU if available, or a configurable soft-core IOMMU that we provide. We explore different TLB configurations and provide a comparison with other designs for shared virtual memory to gain insight on performance-critical IOMMU components. Experimental results using pointer-rich benchmarks show that our framework not only simplifies FPGA-accelerated application development, it also achieves up to 13x speedup compared to traditional copy-based offloading.