The network transport layer is increasingly implemented in the NIC hardware to meet the performance demands of modern workloads, but this has made it difficult to evolve or deploy new transport protocols. Existing approaches either fix protocol logic in the data-path or build protocol-specific assumptions into the architecture that limit the range of protocols that can be supported on a single hardware substrate. We present PITA, a protocol-independent transport architecture that enables full data-path programmability while sustaining line-rate performance. PITA eliminates protocol-specific assumptions by structuring the data-path around a uniform abstraction over events, state, and instructions, and rethinks core components, including scheduling, packet generation, and data reassembly, to operate on this abstraction. We evaluate PITA along key dimensions reflecting the goals of its protocol-agnostic datapath design. Specifically, we show that PITA supports diverse protocol semantics by showing it can implement TCP and \roce on the same data path and preserve their distinct end-to-end behavior. Through targeted microbenchmarks and synthesis on Alveo U250 cards, we show that PITA's redesigned components sustain high performance under demanding conditions, with modest hardware overhead and meeting timing at 250MHz.

翻译：网络传输层越来越多地在网卡硬件中实现，以满足现代工作负载的性能需求，但这使得演进或部署新的传输协议变得困难。现有方法要么在数据路径中固定协议逻辑，要么在架构中引入协议特定的假设，从而限制了在单一硬件基板上可支持的协议范围。我们提出了PITA，一种协议无关的传输架构，它在维持线路速率性能的同时，实现了完整的数据路径可编程性。PITA通过围绕事件、状态和指令的统一抽象来构建数据路径，消除了协议特定的假设，并重新设计了核心组件（包括调度、数据包生成和数据重组），使其在此抽象上运行。我们从反映其协议无关数据路径设计目标的关键维度对PITA进行了评估。具体而言，我们展示了PITA通过在相同数据路径上实现TCP和RoCE并保留它们各自不同的端到端行为，支持多样化的协议语义。通过针对性的微基准测试和在Alveo U250板卡上的综合测试，我们证明了PITA重新设计的组件在严苛条件下能够维持高性能，硬件开销适中，并在250MHz频率下满足时序要求。