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3D integration opens up new opportunities for future multiprocessor chips by enabling fast and highly scalable 3D Network-on-Chip (NoC) topologies. However, in an aim to reduce the cost of Through-silicon via (TSV), partially vertically connected NoCs, in which only a few vertical TSV links are available, have been gaining relevance. To reliably route packets under such conditions, we introduce a lightweight, efficient and highly resilient adaptive routing algorithm targeting partially vertically connected 3D-NoCs named First-Last. It requires a very low number of virtual channels (VCs) to achieve deadlock-freedom (2 VCs in the East and North directions and 1 VC in all other directions), and guarantees packet delivery as long as one healthy TSV connecting all layers is available anywhere in the network. An improved version of our algorithm, named Enhanced-First-Last is also introduced and shown to dramatically improve performance under low TSV availability while still using less virtual channels than state-of-the-art algorithms. A comprehensive evaluation of the cost and performance of our algorithms is performed to demonstrate their merits with respects to existing solutions. [ABSTRACT FROM AUTHOR]

2D-NoCs have been the mainstream approach used to interconnect multi-core systems. 3D-NoCs have emerged to compensate for deficiencies of 2D-NoCs such as long latency and power overhead. A low-latency routing algorithm for 3D-NoC is designed to accommodate high-speed communication between cores. Both simulation and analytical models are applied to estimate the communication latency of NoCs. Generally, simulations are time-consuming and slow down the design process. Analytical models provide, within a fraction of the time, nearly accurate results which can be used by simulation to fine-tune the design. In this paper, a high performance and adaptive routing algorithm has been proposed for partially connected 3D-NoCs. Latency of the routing algorithm under different traffic patterns, different number of elevators and different elevator assignment mechanisms are reported. An analytical model, tailored to the adaptivity of the algorithm and under low traffic scenarios, has been developed and the results have been verified by simulation. According to the results, simulation and analytical results are consistent within a 10 percent margin. [ABSTRACT FROM AUTHOR]

In modern many-core architectures, advanced on-chip networks provide the means of communication for the cores. This greatly complicates the design and verification of the cache coherence protocols deployed by those cores. A common approach to deal with this complexity is to decompose the whole system into the protocol and the network. This decomposition is, however, not always possible. For example, unexpected deadlocks can emerge when a deadlock-free protocol and a deadlock-free network are combined. This paper proposes a compositional methodology: prove properties over a network, prove properties over a protocol, and infer properties over the system as a whole. Our methodology is based on theorems that show that such decomposition is possible by having sufficiently large local buffers at the cores. We apply this methodology to verify several protocols such as MI, MSI, MESI and MEUSI running on top of advanced interconnects with adaptive routing. [ABSTRACT FROM AUTHOR]

Fault-tolerant minimal routing algorithms aim at finding a Manhattan path between the source and destination nodes and route around all faulty nodes. Additionally, some non-faulty nodes that are helpless to make up of a fault-tolerant minimal path should also be routed around. How to label such non-faulty nodes efficiently is a major challenge. State-of-the-art solutions could not address it very well. We propose a path-counter method. It can label every node that are helpless to make up of a fault-tolerant minimal path with low time complexity. By counter the number of fault-tolerant minimal paths, it can: support arbitrary fault distribution, check the existence of fault-tolerant minimal paths, not sacrifice any available fault-tolerant minimal paths. [ABSTRACT FROM AUTHOR]

3D ICs can take advantage of a scalable communication platform, commonly referred to as the Networks-on-Chip (NoC). In the basic form of 3D-NoC, all routers are vertically connected. Partially connected 3D-NoC has emerged because of physical limitations of using vertical links. Routing is of great importance in such partially connected architectures. A high-performance, fault-tolerant and adaptive routing strategy with respect to the communication flow among the cores is crucial while freedom from livelock and deadlock has to be guaranteed. In this paper we introduce a new routing algorithm for partially connected 3D-NoCs. The routing algorithm is adaptive and tolerates the faults on vertical links as compared to the predesigned routing algorithms. Our results show a $40-50\%$ improvement in the fraction of intact inter-level communications when the fault tolerant algorithm is used. This routing algorithm is light-weight and has only one virtual channel along the $Y$ dimension. [ABSTRACT FROM AUTHOR]