Analytical Model Of Multi-path Minimal Routing NoC Based On Network Calculus

The technology of Network-on-Chip (NoC) is becoming mature and has begun to gradually applied to industry. Worst-case performance evaluation is an important index for NoC design, but the research on it is less than that on average performance of NoC. NoC worst-case performance evaluation is conducive to acquire the boundary of network performance for designers and enhance the confidence of the designer. In this paper, with worst-case delay bound in multi-path routing NoC as objects, the delay bound analysis model is built, and conflict prediction mechanism is established based on network calculus. Then optimization strategy for worst-case delay bound is put forward. The main work is as follows:(1) The multi-exports aggregate traffic modelSince the Fidler model is not accurate enough, a multi-exports aggregate traffic model based on network calculus is built according to the characteristics of free parameters when dealing with the equivalent service curve by single-export aggregate traffic model. Thus the solving process becomes easier and the difference between the results and the simulation is optimized of 72.2% compared with Fidler model.(2) Description on the congestion of NoCAs the complex contention in the network, a new contention matrix is constructed in this paper, including the characteristic of contention flow and split situation, to describe the contention information among the traffic flow in the network. The contention matrix clearly indicates the contention situation of target flows in every routing node. After knowing the network contention situation, the size of the target flows’contention on each path can be got.(3) Ohm’s Law-like Traffic Splitting StrategySince muti-path routing NoC has serious network congestion, Ohm’s Law-like traffic splitting strategy is proposed in this paper. According to the contention matrix, the path congestion factor of each sub-flow can be got. The congestion factor describing path congestion can be regarded as the resistance of the current on this path, and the congestion factors of all target sub-flows can be taken as a series of parallel resistances. Ohm’s Law-like traffic splitting strategy is used to adjust the traffic on each sub-flow. According to the splitting model proposed, the rate of target flows are distributed so that most of data flows would be sent to the path with smaller contention and a small number of data flows would be sent to the path with larger contention, so as to balance load and optimize worst-case delay bound.(4) RTL simulation platform based on VerilogIn view of the existing simulation platform we can not solve the problem of Ohm’s Law-like traffic splitting strategy; This paper has set up a RTL simulation platform based on Verilog; The simulation platform encapsulates Ohm’s Law-like traffic splitting model to an offline control core, and we distribute the rate of flow from routing nodes by splitting rate from the core so that we optimize the networks worst-case performance.