Adaptive communication mechanism for accelerating MPI functions in NoC-based multicore processors

Abstract

Multicore designs have emerged as the dominant organization for future high-performance microprocessors. Communication in such designs is often enabled by Networks-on-Chip (NoCs). A new trend in such architectures is to fit a Message Passing Interface (MPI) programming model on NoCs to achieve optimal parallel application performance. A key issue in designing MPI over NoCs is communication protocol, which has not been explored in previous research. This article advocates a hardware-supported communication mechanism using a protocol-adaptive approach to adjust to varying NoC configurations (e.g., number of buffers) and workload behavior (e.g., number of messages). We propose the ADaptive Communication Mechanism (ADCM), a hybrid protocol that involves behavior similar to buffered communication when sufficient buffer is available in the receiver to that similar to a synchronous protocol when buffers in the receiver are limited. ADCM adapts dynamically by deciding communication protocol on a per-request basis using a local estimate of recent buffer utilization. ADCM attempts to combine both the advantages of buffered and synchronous communication modes to achieve enhanced throughput and performance. Simulations of various workloads show that the proposed communication mechanism can be effectively used in future NoC designs.