Operating System and Architectural Implications of Programmable Network Interfaces

可编程网络接口的操作系统和架构含义

• 批准号: 0209174
• 负责人: Scott Rixner
• 金额: $ 30.34万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0209174&HistoricalAwards=false
• 关键词: Operating; System; Architectural; Implications; Programmable

Networking server performance has improved substantially in recent years, due mostly to rapid developments in application and operating system level software and, to a lesser extent, improved hardware in the network interface. These developments have greatly reduced the CPU load of networkservers, the amount of main memory used for networking, and the bandwidth requirements of data transfers between the CPU and its main memory. However, when the server prepares to send its data out onto the network, the network interface must still use DMA to fetch each piece of data to be transmittedfrom the main memory of the host processor, and this overhead increases work for both the local interconnect (for example, the PCI bus) and the main memory system. As network capacities increase, the bandwidth of these resources will become a performance bottleneck.While many network interfaces continue to use special-purpose hardware, several programmable network interfaces exist. These programmable network interfaces are currently used to offload computations such as TCP/IP checksum calculation from the CPU. Such optimizations provide substantial benefits, but they underutilize the flexibility of programmable network processors by using them only for fixed functionality that is already implemented efficiently in special-purpose hardware. A key deficiency isthat current network interfaces use storage primarily as buffer space for incoming and outgoing transmissions, thus retaining the logical semantics of a simple wire. In reality, however, a programmable network interface is a node in a heterogeneous multiprocessor system, where the CPU and main memoryform one node and the network processor and its local memory form another.We propose to exploit the heterogeneous multiprocessing capability of a server with a programmable network interface through better utilization of both storage and computation. First, we intend to use some of the local memory on the network interface as a cache of frequently-served content.This will substantially reduce the load on the local interconnect, the system memory, and the CPU for setting up DMA transfers. Second, we intend to explore ways to utilize the flexible computation provided by network processors in the network interface. This will further improve server performance by offloading demanding networking tasks from the CPU and also enable additional services beyond those offered today by our richer use of storage on the interface.Finally, we will consider the impact of these proposals on network processor architectures. Network processors today have been designed primarily for routers and low-level packet processing. However, our proposals lead to substantially different workloads for programmable network interfaces inservers, requiring systems with flexibility akin to modern high-performance microprocessors along with the packet processing efficiency of network processors. We plan to investigate various hybrid designs, as well as tighter coupling between the CPU and network processor.

近年来，网络服务器的性能有了很大的提高，这主要是由于应用程序和操作系统级软件的快速发展，以及网络接口硬件的改进。这些发展大大减少了网络服务器的CPU负载，用于网络的主存储器的数量，以及CPU和主存储器之间数据传输的带宽要求。然而，当服务器准备将其数据发送到网络上时，网络接口仍然必须使用DMA从主机处理器的主存储器中获取要传输的每一条数据，并且这种开销增加了本地互连（例如，PCI总线）和主存储器系统的工作。随着网络容量的增加，这些资源的带宽将成为性能瓶颈。虽然许多网络接口继续使用专用硬件，但仍存在一些可编程网络接口。这些可编程网络接口目前用于从CPU卸载诸如TCP/IP校验和计算之类的计算。这样的优化提供了实质性的好处，但是它们通过仅将可编程网络处理器用于已经在专用硬件中有效实现的固定功能而未充分利用可编程网络处理器的灵活性。 一个关键的缺陷是，当前的网络接口主要将存储器用作传入和传出传输的缓冲空间，因此保留了简单线路的逻辑语义。然而，在现实中，一个可编程网络接口是一个异构多处理器系统中的一个节点，其中CPU和主存储器形成一个节点和网络处理器和它的本地存储器形成another.We建议开发异构多处理能力的服务器与可编程网络接口通过更好地利用存储和计算。 首先，我们打算使用网络接口上的一些本地内存作为频繁服务内容的缓存，这将大大减少本地互连、系统内存和CPU上用于设置DMA传输的负载。 其次，我们打算探索如何利用网络接口中的网络处理器提供的灵活计算。 这将进一步提高服务器的性能，从CPU卸载要求苛刻的网络任务，也使额外的服务比我们今天提供的更丰富的使用接口上的存储。最后，我们将考虑这些建议对网络处理器架构的影响。 今天的网络处理器主要是为路由器和低级数据包处理而设计的。 然而，我们的建议导致可编程网络接口插入器的工作量大不相同，需要系统具有类似于现代高性能微处理器的灵活性，沿着具有网络处理器的数据包处理效率。 我们计划研究各种混合设计，以及CPU和网络处理器之间更紧密的耦合。