一個具虛擬通道共享機制之雙向通道網路晶片架構設計

Abstract

在網路晶片架構中，緩衝器 (Buffer) 的大小一直是影響電路在效能、面積、功耗表現上的主要對象之一。如何分配緩存資源便成為相關設計上一個重要的議題。為了能更有效利用緩存資源，在該論文中我們提出一個具有虛擬通道 (Virtual-Channel) 共享機制的雙向通道網路晶片架構；此架構允許網路晶片路由器內不同傳輸方向在閒置時將其所屬的虛擬通道資源分享給相鄰的傳輸方向使用，達到緩解負載流量的目的。透過該共享機制可以有效的提高路由器內緩存資源的利用率，改善網路晶片在負載不平衡狀況下的傳輸效能。本文利用一個精準時脈週期的測試環境進行模擬，從模擬結果可看出具有虛擬通道共享機制之雙向通道網路晶片相對於傳統虛擬通道分配機制之雙向通道網路晶片架構在效能與資源利用率上佔有一定的優勢。

Network-on-Chip (NoC) architecture has been viewed as a possible solution to support the growing design complexity of Multi-Processor System-on-Chip (MPSoCs) since the advent of deep sub-micron technology in recent years. In an NoC design, buffer resources dominate the major power consumption and area overhead of the entire router architecture. How to utilize buffer resources efficiently is always a significant study issue. In this Thesis, we propose a power- and area-efficient router architecture using a Virtual-Channel Sharing (VCS) mechanism to improve the network performance in a Bi-directional NoC (BiNoC) architecture especially under the non-uniform traffic environment. The underlying idea is that each input port in our proposed router can share its idled virtual-channels to the neighboring input ports. In other words, an input port can borrow idled virtual-channels from the adjacent input ports to suffer the temporary high traffic load. The improvement of the routing and virtual-channel utilization flexibility by our proposed VCS mechanism can eliminate the head-of-line blocking efficiently under a constrained number of virtual-channels. The experimental results show that a significant performance improvement, in terms of area overhead and power consumption, can be obtained by our proposed VCS mechanism.