Research On Routing Algorithms For Bufferless Network On Chip

With the development of integrated circuits, more and more IP cores are integrated on asingle chip. Chip transfers from compute-centric to communication-centric, forming a newarchitecture of the integrated circuit-NoC(Network-on-Chip). Presently, though thebuffer-based routing algorithm is the current focus of the NoC research, however the bufferaggravates the cost of chip area and power consumption. After studying the topology androuting algorithm of the bufferless NoC, this paper proposes an improved bufferless NoCalgorithm and then gives an evaluation by simulation experiment.In order to solve the problem, which exist in bufferless routing algorithm based on two-dimensional nxn mesh topology, under high rates of injecting has long network average delay,this paper proposes a DC-BLESS algorithm above on BLESS_PERM algorithm. Thealgorithm draws on the thinking of "Green Wave linkage" in the traffic control, which usingthe strategy that the lower number of the deflection has the higher priority to reduce the trafficin the network, thereby reducing the network latency. For the purpose of preventing some dataflits from deflecting too many times, we take a cleaning operation to increase the priority ofdata flits in the situation of that deflection frequency is greater than the threshold value. Thenaccording to the weakness of the large diameter of two dimensional n×n mesh network andthe long distance between the vertices, the Z-mesh topology is proposed. This structureconnects the three pairs of vertices of the mesh structure, the upper left and upper right, upperright and lower left, lower left and lower right, thereby shorted the network diameter of thetopology and reduced the network latency. Finally, according to the character of the Z-Meshstructure, we modify the calculations ways of the valid port of data flits, proposeZ-DC-BLESS algorithm based on the Z-mesh topology and reduce the average latency of thenetwork.So as to analysis the proposed DC-BLESS and Z-DC-BLESS algorithm, this paper hasdesigned performance simulator of the NoC routing algorithm. By comparing the simulationresults of the three algorithms BLESS_PERM, DC-BLESS and Z-DC-BLESS, we find thatthe network average delays of DC-BLESS algorithm have been reduced compared withBLESS_PERM algorithm in the three traffic patterns-uniform random, displace and hotspot. And in the three modes the best was displace mode (decreasing by18%). While in the samethree modes, the network average delays of Z-DC-BLESS algorithm also have been cut downin contrast with the DC-BLESS algorithm and the best was still displace mode (decreasing by19.9%).