Narrow Results

Through simulation, we studied the performance of three adaptive “wormhole” routing strategies, and compared them with static routing. Since adaptive routing is susceptible to deadlock, an abort-and-retry strategy was used to prevent it from arising. The impact of packetization of long messages and buffering at message destinations were also studied. Results are presented and analyzed for a variety of hardware configurations and traffic conditions. The combination of adaptive routing, abort-and-retry, and buffering at the destination is shown to achieve excellent performance for modest cost.

We consider here reduction of send latencies for send-and-forget type communications, where senders do not reuse data that have already been sent. We introduce a commit based message sending approach, and describe the corresponding application programming interfaces. These interfaces allow applications to take advantage of message buffering, such as overlapping of computations and communications, while avoiding performance degradation due to intermediate memory copy. The approach works by allowing applications to safely access the implementation buffer through the provided interfaces. Experimental results show that the new approach is effective, and reduces the interface latency significantly compared to related approaches. Since send-and-forget type communications are often observed in skeletal programming, we demonstrate the approach by implementing a pipeline algorithmic skeleton.