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Network-on-chip facilitates glueless interconnection of various on-chip components in the forthcoming system-on-chips. As in the case of any new technology, security is a major concern in network-on-chip (NoC) design too. In this work, we explore a covert threat model for multiprocessor system-on-chips (MPSoCs) stemming from the use of malicious third-party network-on-chips (NoCs). We illustrate that a rogue NoC (rNoC) can selectively disrupt the perceived availability of on-chip resources, thereby causing large performance bottlenecks for the applications running on the MPSoC platform. Further, to counter the threat posed by rNoC, we propose a runtime latency auditor that enables an MPSoC integrator to monitor the trustworthiness of the deployed NoC throughout the chip lifetime. We also discuss measures that can be taken to minimize the impact of a rNoC, once it is detected. Our comprehensive cross-layer analysis of our novel detection technique indicates modest overheads of 12.73% in area, 9.844% in power, and 5.4% in terms of network latency.

Continuous technology scaling has made aging mechanisms, such as negative bias temperature instability and electromigration primary concerns in network-on-chip (NoC) designs. In this paper, we extensively analyze the effects of these aging mechanisms on NoC routers and links. We observe a critical need of a robust aging-aware routing algorithm that not only reduces power-performance overheads caused due to aging degradation, but also minimizes the stress experienced by heavily utilized routers and links. To solve this problem, we propose an aging-aware adaptive routing algorithm and a router microarchitecture that routes the packets along the paths, which are both least congested and experience minimum aging degradation. After an extensive experimental analysis using real workloads, we observe 13% and 12.17% average overhead reduction in network latency and energy–delay product per flit, a 10.4% improvement in performance, and a 60% improvement in mean time to failure using our aging-aware routing algorithm.

In this paper, we propose a covert threat model for MPSoCs designed using 3rd party Network-on-Chips (NoC). We illustrate that a malicious NoC can disrupt the availability of on-chip resources, thereby causing large performance bottlenecks for the software running on the MPSoC platform. We then propose a runtime latency auditor that enables an MPSoC integrator to monitor the trustworthiness of the deployed NoC throughout the chip lifetime. For the proposed technique, our comprehensive cross-layer analysis indicates modest overheads of 12.73% in area, 9.844% in power and 5.4% in terms of network latency.

Aggressive technology scaling exacerbates the problem of voltage emergencies in emerging MPSoC systems. Network-on-Chips, the de-facto standard for connecting on-chip components in forthcoming devices play a central role in providing robust and reliable communication. In this work, we propose DrNoC (droop resilient network-on-chip)-two microarchitectural techniques to mitigate voltage emergency-induced timing errors in NoCs and preserve error-free communication throughout the network. DrNoC employs frequency downscaling and a pipeline error-recovery mechanism to reclaim corrupted flits in the router. Compared to the recently proposed NSFTR fault-tolerant technique, DrNoC offers a 27% improvement in energy-delay efficiency.

Network-On-Chips (NoCs) have become the standard communication platform for future massively parallel systems due to their performance, flexibility and scalability advantages. However, reliability issues brought about by scaling in the sub-20nm era threaten to undermine the benefits offered by NoCs. In this paper, we showthat QoS policies exacerbate the reliability profile of an exascale system. To mitigate this imposing challenge, we propose Dynamic Wearout Resilient Routing (DWRR) algorithms in QoS-enabled exascale NoCs. Our proposal includes two novel DWRR algorithms enabled by a critical-path monitor and a broadcast-based routing configuration. Using PARSEC benchmarks, our best algorithm improves QoS and long-term sustainability (Mean Time To Failure) of the system by an average of 16% and 25% compared to a state-of-the-art fault tolerant technique, respectively. Copyright 2014 ACM.

In this paper, we uncover a novel and imminent threat to an emerging computing paradigm: MPSoCs built with 3rd party IP NoCs. We demonstrate that a compromised NoC (C-NoC) can enable a range of security attacks with an accomplice software component. To counteract these threats, we propose Fort-NoCs, a series of techniques that work together to provide protection from a C-NoC in an MPSoC. Fort-NoCs's foolproof protection disables covert backdoor activation, and reduces the chance of a successful side-channel attack by "clouding" the information obtained by an attacker. Compared to recently proposed techniques, Fort-NoCs offers a substantially better protection with lower overheads. Copyright 2014 ACM.

The trend towards massive parallel computing has necessitated the need for an On-Chip communication framework that can scale well with the increasing number of cores. At the same time, technology scaling has made transistors susceptible to a multitude of reliability issues (NBTI, HCI, TDDB). In this work, we propose an HCI-Tolerant microarchitecture for an NoC Router by manipulating the switching activity around the circuit. We find that most of the switching activity (the primary cause of HCI degradation) are only concentrated in a few parts of the circuit, severely degrading some portions more than others. Our techniques increase the lifetime of an NoC router by balancing this switching activity. Compared to an NoC without any reliability techniques, our best schemes improve the switching activity distribution, clock cycle degradation, system performance and energy delay product per flit by 19%, 26%, 11% and 17%, respectively, on an average.

Early prediction of an upcoming timing violation presents a tremendous opportunity to mask the performance overhead of tolerating these faults. In this paper, we explore several techniques for optimizing instruction scheduling in an Out-of-Order pipeline, exploiting this new perspective in robust system design. Compared to recently proposed stall based techniques for tolerating predictabletiming violations, we demonstrate a massive reduction in performance overhead, while supporting correct execution in faulty environments (64-97% across different benchmarks). Copyright © 2013 ACM.

Three-dimensional Multicore Systems present unique opportunities for proximity driven data placement in the memory banks. Coupled with distributed memory controllers, a design trend seen in recent systems, we propose a Dynamic Memory Relocator for 3D Multicores (DMR3D) to dynamically migrate physical pages among different memory controllers. Our proposed technique avoids long interconnect delays, and increases the use of vertical interconnect, thereby substantially reducing memory access latency and communication energy. Our techniques show 30% and 25% average performance and communication energy improvement on real world applications.

Degradation of transistor parameter values due to Negative Bias Temperature Instability (NBTI) has emerged as a major reliability problem in current and future transistor generations. NBTI Aging of SRAM cell leads to a lower noise margin, thereby increasing the failure rate. The physical register file, which consists of an array of SRAM cells, can suffer from data loss, leading to system failure. In this paper, we explore a novel approach by investigating NBTI stress and mitigation at the instruction granularity. While a wide range of NBTI stress exists in different registers, the stress induced by specific instructions is highly predictable. Using such a prediction mechanism, we propose an NBTI tolerant power efficient physical register file design. Our approach improves the noise margin in a register file by 20%, 32%, and 125% for the 45nm, 32nm, and 22nm technology nodes, respectively. Overall, we observe 14.8% power saving and a 19.8% area penalty in the register file.

We report an implementation of a 32-bit DLX microprocessor capable of operating in a dual core environment. The processor was modified for it to be capable of operating atomic instructions, a requirement in a dual core environment. The dual core environment was simulated using a similar core acting as a pseudo slave core. The resulting processor can then be interfaced with another instance of the same processor to function as a dual core processor. It can also be interfaced with a DSP co-processor that is compatible with the handshaking protocols of the processor. The resulting implementation yielded a power reduction of 17.9% (due to a more efficient register file) and an area overhead of 23% (due to additional blocks needed for dual core capability) compared to previous DLX implementations of the laboratory.