流水通道──一种高速的MPP系统互连

PIPELINED CHANNEL:A HIGH-SPEED NETWORK INTERCONNECT IN MPP

传统大规模并行处理机系统中的互连网络及路由器在强同步方式下工作，相邻路由器间消息的传送必须保证一个周期内完成，系统互连长度成为影响网络主频的重要因素，同时也限制了系统的可扩展性．采用流水通道可在一条通道上同时传送多个数据，使得网络的主频独立于线的长度，提高了网络的传输速率，本文介绍了这一思想，并对流水通道互连网络的实现技术进行研究，着重阐述了源同步传输、切换技术、流控策略等几个关键技术问题．

In a traditional massively parallel processors(MPP), the transmission of message must be finished in one cycle between two routers linked by a wire, so the clock of the network is limited by the wire lengths, and this limits the scalability of MPP system. But in a pipelined-channel interconnection network, multiple bits may be simultaneously in flight on a single wire, this allows the cycle time of the network to be independent of the wire lengths, significantly enhancing the transmission rate of network, and making the system more scalable. Pipelined-channels have long been used in wide area networks and local area networks, but are not widely used in MPP systems. In order to enhance the performance of MPP system,new generation MPP system such as CRAY T-3E begin to use pipelined-channel interconnect. This paper introduces the idea of pipelined-channel, presents the design of interconnection network in MPP with it, focuses on several critical technologies of it, especially on source synchronize transmitting technology, switching technology, flow control, and routing algorithm. Finally, it gives a plesoichronous router (PCR) design based on pipelined-channel in 2D-mesh network.