FPGAs in the Cloud: Booting Virtualized Hardware Accelerators with OpenStack

We present a new approach for integrating virtualized FPGA-based hardware accelerators into commercialscale cloud computing systems, with minimal virtualization overhead. Partially reconfigurable regions across multiple FPGAs are offered as generic cloud resources through OpenStack (opensource cloud software), thereby allowing users to "boot" custom designed or predefined network-connected hardware accelerators with the same commands they would use to boot a regular Virtual Machine. We propose a hardware and software framework to enable this virtualization. This is a first attempt at closely fitting FPGAs into existing cloud computing models, where resources are virtualized, flexible, and have the illusion of infinite scalability. Our system can set up and tear down virtual accelerators in approximately 2.6 seconds on average, much faster than regular virtual machines. The static virtualization hardware on the physical FPGAs causes only a three cycle latency increase and a one cycle pipeline stall per packet in accelerators when compared to a non-virtualized system. We present a case study analyzing the design and performance of an application-level load balancer using a fully implemented prototype of our system. Our study shows that FPGA cloud compute resources can easily outperform virtual machines, while the system's virtualization and abstraction significantly reduces design iteration time and design complexity.