Dagger: Accelerating RPCs in Cloud Microservices Through Tightly-Coupled Reconfigurable NICs

TL;DR

Dagger is a reconfigurable FPGA-based NIC fabric that accelerates cloud RPCs, significantly boosting throughput and reducing latency in microservices environments by offloading RPC stacks and using memory interconnects.

Contribution

Introducing Dagger, a novel FPGA-based NIC architecture that offloads entire RPC stacks and uses memory interconnects for high performance and flexibility in microservices.

Findings

Achieves 1.3-3.8x higher per-core RPC throughput than software and RDMA systems.

Scales up to 84 million requests per second with low latency.

Enables easy porting of third-party applications like memcached with minimal code changes.

Abstract

The ongoing shift of cloud services from monolithic designs to microservices creates high demand for efficient and high performance datacenter networking stacks, optimized for fine-grained workloads. Commodity networking systems based on software stacks and peripheral NICs introduce high overheads when it comes to delivering small messages. We present Dagger, a hardware acceleration fabric for cloud RPCs based on FPGAs, where the accelerator is closely-coupled with the host processor over a configurable memory interconnect. The three key design principle of Dagger are: (1) offloading the entire RPC stack to an FPGA-based NIC, (2) leveraging memory interconnects instead of PCIe buses as the interface with the host CPU, and (3) making the acceleration fabric reconfigurable, so it can accommodate the diverse needs of microservices. We show that the combination of these principles significantly improves the efficiency and performance of cloud RPC systems while preserving their generality. Dagger achieves 1.3-3.8x higher per-core RPC throughput compared to both highly-optimized software stacks, and systems using specialized RDMA adapters. It also scales up to 84 Mrps with 8 threads on 4 CPU cores, while maintaining state-of-the-art us-scale tail latency. We also demonstrate that large third-party applications, like memcached and MICA KVS, can be easily ported on Dagger with minimal changes to their codebase, bringing their median and tail KVS access latency down to 2.8 - 3.5us and 5.4 - 7.8us, respectively. Finally, we show that Dagger is beneficial for multi-tier end-to-end microservices with different threading models by evaluating it using an 8-tier application implementing a flight check-in service.