Minimizing latency and power are key goals in the design of NoC routers. Different proposals combine lookahead routing and router bypass to skip the arbitration and buffering, reducing router delay. However, the conditions to use them requires completely empty buffers in the intermediate routers. This restricts the amount of flits that use the bypass pipeline especially at medium and high loads, increasing latency and power.

This paper presents NEBB, Non-Empty Buffer Bypass, a mechanism that allows to bypass flits even if the buffers to bypass are not empty. The mechanism applies to wormhole and virtual-cut-through, each of them with different advantages. NEBB-Hybrid is proposed to employ the best flow control in each situation. The mechanism is extended to torus topologies, using FBFC and shared buffers.

The proposals have been evaluated using Booksim, showing up to 75% reduction of the buffered flits for single-flit packets, which translates into latency and dynamic power reductions of up to 30% and 23% respectively. For bimodal traffic, these improvements are 20 and 21% respectively. Additionally, the bypass utilization is largely independent of the number of VCs when using shared buffers and very competitive with few private ones, allowing to simplify the allocation mechanisms.

最小化延迟和功耗是NoC路由器设计的主要目标。不同的建议结合了先行路由和路由器旁路来跳过仲裁和缓冲，从而减少了路由器延迟。但是，使用它们的条件要求中间路由器中的缓冲区完全空白。这限制了使用旁路管道的碎片数量，尤其是在中等和高负载下，增加了等待时间和功率。

本文介绍了NEBB，非空缓冲区绕过，一种机制，即使要绕过的缓冲区不为空，也可以绕过碎片。该机制适用于虫洞和虚拟直通，它们各自具有不同的优势。建议将NEBB-Hybrid应用于每种情况下的最佳流量控制。该机制使用FBFC和共享缓冲区扩展到环面拓扑。

使用Booksim对提议进行了评估，结果显示单行数据包的缓冲数据减少了75％，这分别意味着延迟和动态功耗分别减少了30％和23％。对于双峰运输，这些改进分别为20％和21％。此外，当使用共享缓冲区时，旁路利用率在很大程度上与VC的数量无关，并且与少数专用缓冲区的竞争非常激烈，从而简化了分配机制。