arXiv subjects

Ryan Kosta

Publications and source records attributed to Ryan Kosta.

2 recordsLinked to original sources

arXiv2023

SIRD: A Sender-Informed, Receiver-Driven Datacenter Transport Protocol

Datacenter congestion control protocols are challenged to navigate the throughput-buffering trade-off while relative packet buffer capacity is trending lower year-over-year. In this context, receiver-driven protocols -- which schedule packet transmissions instead of reacting to congestion -- excel when the bottleneck lies at the ToR-to-receiver link. However, when multiple receivers must use a shared link (e.g., ToR to Spine), their independent schedules can conflict. We present SIRD, a receiver-driven congestion control protocol designed around the simple insight that single-owner links should be scheduled, while shared links should be managed with reactive control algorithms. The approach allows receivers to both precisely schedule their downlinks and to coordinate over shared bottlenecks. Critically, SIRD also treats sender uplinks as shared links, enabling the flow of congestion feedback from senders to receivers, which then adapt their scheduling to each sender's real-time capacity. This results in tight scheduling, enabling high bandwidth utilization with little contention, and thus minimal latency-inducing buffering in the fabric. We implement SIRD on top of the Caladan stack and show that SIRD's asymmetric design can deliver 100Gbps in software while keeping network queuing minimal. We further compare SIRD to state-of-the-art receiver-driven protocols (Homa, dcPIM, and ExpressPass) and production-grade reactive protocols (Swift and DCTCP) and show that SIRD is uniquely able to simultaneously maximize link utilization, minimize queuing, and obtain near-optimal latency.

cs.NI↗

arXiv2022

SuperNIC: A Hardware-Based, Programmable, and Multi-Tenant SmartNIC

With CPU scaling slowing down in today's data centers, more functionalities are being offloaded from the CPU to auxiliary devices. One such device is the SmartNIC, which is being increasingly adopted in data centers. In today's cloud environment, VMs on the same server can each have their own network computation (or network tasks) or workflows of network tasks to offload to a SmartNIC. These network tasks can be dynamically added/removed as VMs come and go and can be shared across VMs. Such dynamism demands that a SmartNIC not only schedules and processes packets but also manages and executes offloaded network tasks for different users. Although software solutions like an OS exist for managing software-based network tasks, such software-based SmartNICs cannot keep up with the quickly increasing data-center network speed. This paper proposes a new SmartNIC platform called SuperNIC that allows multiple tenants to efficiently and safely offload FPGA-based network computation DAGs. For efficiency and scalability, our core idea is to group network tasks into chains that are connected and scheduled as one unit. We further propose techniques to automatically scale network task chains with different types of parallelism. Moreover, we propose a fair share mechanism that considers both fair space sharing and fair time sharing of different types of hardware resources. Our FPGA prototype of SuperNIC achieves high bandwidth, low latency performance whilst efficiently utilizing and fairly sharing resources.

cs.DC↗