Leaving One Slot Empty: Flit Bubble Flow Control for Torus Cache-Coherent NoCs

摘要: Short and long packets co-exist in cache-coherent NoCs. Existing designs for torus networks do not efficiently handle variable-size packets. For deadlock free operations, a design uses two VCs, which negatively affects the router frequency. Some optimizations use one VC. Yet, they regard all as maximum-length packets, inefficiently utilizing precious buffers. We propose flit bubble flow control (FBFC), maintains flit-size buffer slot to avoid deadlock. FBFC VC, does treat short ones. It achieves both high frequency efficient utilization. performs 92.8 34.2 percent better than LBS CBS synthetic traffic $4 \times 4$ torus. The gains increase larger networks; are 107.2 40.1 an $8 8$ average 13.0 speedup over PARSEC workloads. Our results also show that is more power CBS, with mesh.