Cut-through delivery in Trapeze: An exercise in low-latency messaging

New network technology continues to improve both the latency and bandwidth of communication in computer clusters. The fastest high-speed networks approach or exceed the I/O bus bandwidths of “gigabit-ready” hosts. These advances introduce new considerations for the design of network interfaces and messaging systems for low-latency communication. This paper investigates cut-through delivery, a technique for overlapping host I/O DMA transfers with network traversal. Cut-through delivery significantly reduces end-to-end latency of large messages, which are often critical for application performance. We have implemented cut-through delivery in Trapeze, a new messaging substrate for network memory and other distributed operating system services. Our current Trapeze prototype is capable of demand-fetching 8 K virtual memory pages in 200 μs across a Myrinet cluster of DEC AlphaStations