CABSR: Congestion Agent Based Source Routing for Network-on-Chip

Network-on-chip (NoC) has recently emerged as a primary paradigm for interconnecting ever increasing number of on-chip cores in future chip-multiprocessors (CMPs). As the advent of big data era, high volume of traffic injection, combined with the ever-changing patterns will exert severe pressure on some hotspots, leading to serious traffic congestion. These hot nodes will exhaust up the communication resources in those areas quickly, and prompt the expansion of congestion tree, which can deteriorate the global traffic condition. In this work, we propose a novel low-cost routing mechanism called Congestion Agent Based Source Routing (CABSR). We set special routing agents called Congestion Agents(CAs) on the edge of congestion area, which maintain the congestion information of an extended range of area. CAs take charge of throttling flows through the congested link, calculating a new appropriate path to help the packet penetrate the congestion area. Experimental results show that compared with oblivious DOR routing, local-adaptive and regional adaptive routing, CABSR achieves performance improvements by 8.3% and 9.24% on average in terms of average packet latency and throughput respectively. It proves that CABSR can efficiently alleviate the congestion condition, balance the load, and inhibit the expansion of congestion tree.