A Hardware Accelerator for Protocol Buffers

Serialization frameworks are a fundamental component of scale-out systems, but introduce significant compute overheads. However, they are amenable to acceleration with specialized hardware. To understand the trade-offs involved in architecting such an accelerator, we present the first in-depth study of serialization framework usage at scale by profiling Protocol Buffers ("protobuf") usage across Google's datacenter fleet. We use this data to build Hy-perProtoBench, an open-source benchmark representative of key serialization-framework user services at scale. In doing so, we identify key insights that challenge prevailing assumptions about serialization framework usage.

We use these insights to develop a novel hardware accelerator for protobufs, implemented in RTL and integrated into a RISC-V SoC. Applications can easily harness the accelerator, as it integrates with a modified version of the open-source protobuf library and is wire-compatible with standard protobufs. We have fully opensourced our RTL, which, to the best of our knowledge, is the only such implementation currently available to the community.

We also present a first-of-its-kind, end-to-end evaluation of our entire RTL-based system running hyperscale-derived benchmarks and microbenchmarks. We boot Linux on the system using FireSim to run these benchmarks and implement the design in a commercial 22nm FinFET process to obtain area and frequency metrics. We demonstrate an average 6.2× to 11.2× performance improvement vs. our baseline RISC-V SoC with BOOM OoO cores and despite the RISC-V SoC's weaker uncore/supporting components, an average 3.8× improvement vs. a Xeon-based server.