Abstract
As more processors are integrated into a single chip, a robust interconnection network between them is becoming more important consequently. Allocator, a critical component in a router, plays a key role in determining which flit would be delivered forward through crossbar switch. An efficient allocator can achieve better matching quality in each cycle, and thus more flits are capable of being transmitted to their downward routers. As one kind of allocator, separable allocator is a common choice for its simple structure and low cost. However, its simple operation inevitably leads to lower matching quality. To address this problem, bypass buffer is therefore introduced in this research to enhance the utilization of the unused ports induced by the inefficiency of separable allocator. According to the performance and cost evaluation by simulation tools, a design with bypass buffer will get most benefit and bring less cost percentage when there are more virtual channels in a router. Moreover, the more balanced a traffic pattern is, the more bypass buffer could be utilized. Since the increased cost percentage brought about by bypass buffer varies considerably between different router architectures, whether to use bypass buffer would largely depend on the router configuration. As bypass buffer could not improve packet latency at low injection rate, using bypass buffer in a throughput-oriented network is more appropriate than in a latency-oriented network.