Improving Reliability in NoCs by Application-Specific Mapping Combined with Adaptive Fault-Tolerant Method in the Links

Abstract

A strategy to handle multiple defects in the NoC links with almost no impact on the communication delay is presented. The fault-tolerant method can guarantee the functionally of the NoC with multiple defects in any link, and with multiple faulty links. The proposed technique uses information from test phase to map the application and to configure fault-tolerant features along the NoC links. Results from an application remapped in the NoC show that the communication delay is almost unaffected, with minimal impact and overhead when compared to a fault-free system. We also show that our proposal has a variable impact in performance while traditional fault-tolerant solution like Hamming Code has a constant impact. Besides our proposal can save among 15% to 100% the energy when compared Hamming Code.The fault model considers a set of interlink and intralink faults. Several simulations have been made for some fault scenarios, and we show the average communication delay for each one. To show performance results we decided to analyze the impact of each fault case in the 3x4 NoC as shown below:Case I. Original Router without faulty link. The communication time is the best because it runs at 885 MHz, and techniques for fault tolerance are not used.Case II. ARDS router without faulty link. In this case adaptive routing and data splitting are not used, and the communication delay is very similar to the original router, once it uses only one multiplexer to bypass DS block.Case III. ARDS router with intralink faults affecting RR_links using only the adaptive routing strategy. We have inserted 34 intralink faults (except in torus links), one in each RR_link to evaluate the average communication delay in this case. As Case II, the communication delay has almost no impact because DS block is not used.

Fault-Tolerant Techniques to Manage Yield and Power Constraints in Network-on-Chip Interconnections

“…The proposed fault-tolerant techniques tolerate the inter-core faults. The inter-core fault model has been defined by faults happening among any links of the network, and it has been further classified as interlink and intralink [22]. Intralink faults happen when aggressor and victim wire are into the same link.…”

“…Related techniques to mitigate faults in the link usually based on one of the following techniques: Hamming code, parity check, retransmission, redundancy, data splitting, adaptive routing or remapping [2][3][4][5][6][7][8][9][10]22]. Some of them do not need detection and diagnosis offline, because they are always detecting and correcting possible faults at run-time.…”

Online fault detection for Networks-on-Chip interconnect

“…Such performance degradation depends on the traffic patterns, fault rates and routing policies, which is beyond the scope of this paper. However the performance degradation can be minimised by repair techniques through a data splitting method [16], [25] and/or adaptive routing strategy [22] etc. For example, the HLAFT routing [14] has 0.9% and 12.61% throughput degradation under transpose traffic pattern for 5% and 10% fault rates, respectively.…”