Use It or Lose It: Proactive, Deterministic Longevity in Future Chip Multiprocessors

Ever since the VLSI process technology crossed the sub-micron threshold, there is an increased interest in design of fault-tolerant systems to mitigate the wearout of transistors. Hot Carrier Injection (HCI) and Negative Bias Temperature Instability (NBTI) are two prominent usage based transistor degradation mechanisms in the deep sub-micron process technologies. This wearout of transistors can lead to timing violations along the critical paths which will eventually lead to permanent failures of the chip. While there have been many studies which concentrate on decreasing the wearout in a single core, the failure of an individual core need not be catastrophic in the context of Chip Multi-Processors (CMPs). However, a failure in the interconnect in these CMPs can lead to the failure of entire chip as it could lead to protocol-level deadlocks, or even partition away vital components such as the memory controller or other critical I/O. Analysis of HCI and NBTI stresses caused by real workloads on interconnect microachitecture shows that wearout in the CMP on-chip interconnect is correlated with lack of load observed in the network-on-chip routers. It is proven that exercising the wearout-sensitive components of routers under low load with random inputs can decelerate the NBTI wearout. In this work, we propose a novel deterministic approach for the generation of appropriate exercise mode data to maximize the life-time improvement, ensuring design parameter targets are met. The results from this new proposed design yields ~2300x decrease in the rate of CMP wear due to NBTI compared to that of ~28x decrease shown by previous work

Energy and Reliability in Future NOC Interconnected CMPS

In this dissertation, I explore energy and reliability in future NoC (Network-on-Chip) interconnected CMPs (chip multiprocessors) as they have become a first-order constraint in future CMP design. In the first part, we target the root cause of network energy consumption through techniques that reduce link and router-level switching activity. We specifically focus on memory subsystem traffic, as it comprises the bulk of NoC load in a CMP. By transmitting only the flits that contain words that we predicted would be useful using a novel spatial locality predictor, our scheme seeks to reduce network activity. We aim to further lower NoC energy consumption through microarchitectural mechanisms that inhibit datapath switching activity caused by unused words in individual flits. Using simulation-based performance studies and detailed energy models based on synthesized router designs and different link wire types, we show that (a) the pre- diction mechanism achieves very high accuracy, with an average rate of false-unused prediction of just 2.5%; (b) the combined NoC energy savings enabled by the predictor and microarchitectural support are 36% on average and up to 57% in the best case; and (c) there is no system performance penalty as a result of this technique. In the second part, we present a method for dynamic voltage/frequency scaling of networks-on-chip and last level caches in CMP designs, where the shared resources form a single voltage/frequency domain. We develop a new technique for monitoring and control and validate it by running PARSEC benchmarks through full system simulations. These techniques reduce energy-delay product by 46% compared to a state-of-the-art prior work. In the third part, we develop critical path models for HCI- and NBTI-induced wear assuming stress caused under realistic workload conditions, and apply them onto the interconnect microarchitecture. A key finding from this modeling is that, counter to prevailing wisdom, wearout in the CMP on-chip interconnect is correlated with a lack of load observed in the NoC routers, rather than high load. We then develop a novel wearout-decelerating scheme in which routers under low load have their wearout-sensitive components exercised without significantly impacting the router’s cycle time, pipeline depth, and area or power consumption. We subsequently show that the proposed design yields a 13.8∼65× increase in CMP lifetime

Adaptive Distributed Architectures for Future Semiconductor Technologies.

Year after year semiconductor manufacturing has been able to integrate more components in a single computer chip. These improvements have been possible through systematic shrinking in the size of its basic computational element, the transistor. This trend has allowed computers to progressively become faster, more efficient and less expensive. As this trend continues, experts foresee that current computer designs will face new challenges, in utilizing the minuscule devices made available by future semiconductor technologies. Today's microprocessor designs are not fit to overcome these challenges, since they are constrained by their inability to handle component failures by their lack of adaptability to a wide range of custom modules optimized for specific applications and by their limited design modularity. The focus of this thesis is to develop original computer architectures, that can not only survive these new challenges, but also leverage the vast number of transistors available to unlock better performance and efficiency. The work explores and evaluates new software and hardware techniques to enable the development of novel adaptive and modular computer designs. The thesis first explores an infrastructure to quantitatively assess the fallacies of current systems and their inadequacy to operate on unreliable silicon. In light of these findings, specific solutions are then proposed to strengthen digital system architectures, both through hardware and software techniques. The thesis culminates with the proposal of a radically new architecture design that can fully adapt dynamically to operate on the hardware resources available on chip, however limited or abundant those may be.PHDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102405/1/apellegr_1.pd

Exploiting tightly-coupled cores

As we move steadily through the multicore era, and the number of processing cores on each chip continues to rise, parallel computation becomes increasingly important. However, parallelising an application is often difficult because of dependencies between different regions of code which require cores to communicate. Communication is usually slow compared to computation, and so restricts the opportunities for profitable parallelisation. In this work, I explore the opportunities provided when communication between cores has a very low latency and low energy cost. I observe that there are many different ways in which multiple cores can be used to execute a program, allowing more parallelism to be exploited in more situations, and also providing energy savings in some cases. Individual cores can be made very simple and efficient because they do not need to exploit parallelism internally. The communication patterns between cores can be updated frequently to reflect the parallelism available at the time, allowing better utilisation than specialised hardware which is used infrequently. In this dissertation I introduce Loki: a homogeneous, tiled architecture made up of many simple, tightly-coupled cores. I demonstrate the benefits in both performance and energy consumption which can be achieved with this arrangement and observe that it is also likely to have lower design and validation costs and be easier to optimise. I then determine exactly where the performance bottlenecks of the design are, and where the energy is consumed, and look into some more-advanced optimisations which can make parallelism even more profitable

An ad hoc wireless mobile communications model for Special Operations Forces

The digitization of the battlefield enables special operators to use improved communications supported by computer networks across a range of missions. The communications paradigm is evolving toward mobile wireless ad hoc networks. This development enables an autonomous system of mobile nodes supporting peer-to-peer communications in forward-deployed military networks. Ad hoc networks have to establish a reliable, secure, instant, and usually temporary, communication infrastructure and to be able to access in a global communications infrastructure. Our model describes a global communication network supporting the special operator in mobile wireless communications. The main purpose is to provide a handheld wireless communications node which is capable of transferring voice, data, and imagery to and from parallel and vertical command structures within an environment replete with electronic countermeasures. The model will support the representation of requirements such as throughput, quality of service with low power consumption, and low probability of detection/interception. Special Forces are moving toward using commercial-off-the- shelf products and services based on availability and cost effectiveness. Using GloMoSim tool, we run simulations for a direct action scenario and compared the efficiency of on-demand and table-driven routing protocols under different bandwidths and communications loadshttp://www.archive.org/details/adhocwirelessmob00ogutFirst Lieutenant, Turkish ArmyApproved for public release; distribution is unlimited

Intelligent Sensor Networks

In the last decade, wireless or wired sensor networks have attracted much attention. However, most designs target general sensor network issues including protocol stack (routing, MAC, etc.) and security issues. This book focuses on the close integration of sensing, networking, and smart signal processing via machine learning. Based on their world-class research, the authors present the fundamentals of intelligent sensor networks. They cover sensing and sampling, distributed signal processing, and intelligent signal learning. In addition, they present cutting-edge research results from leading experts

Cultivating Sustainable Small-Enterprise Networks: A Way to Enhance Value, Competitiveness and Resilience

The author’s experiences and successes in the 1980’s using “green chemistry” as a leading strategy in the transformation of a textile chemical company’s financial success, led to research on the potential of “sustainability” as a new strategic lens to improve value creation in small to medium sized enterprises (SMEs). Sustainability was offered as a useful strategic lens to aid in transforming SMEs to produce greater value in a world defined as “hot, flat and crowded”, meaning, a world where population pressures on resources, global warming, and the development of global trade are fundamentally changing the nature of enterprise and the consumer’s concept of the role of the corporate enterprises. The dissertation research proceeded along the following steps: · Pursue background research on sustainable development and the concepts for creation of sustainable enterprise · Develop research questions to discover what role “sustainability” might play in strategy planning and successful business strategies for SMEs · Examine the role of SMEs in the global economy · Explore the role and theory of SME network behavior and performance within the boundaries of sustainable development · Report the results of three action research cases where a sustainability lens and transformational framework were inserted as major influences on strategy development over a fiveplus year period · Summarize findings and develop suggestions for ongoing research The research questions developed were directed at discovering: what were the important attributes of sustainable enterprise that could lead SMEs to become more successful, how could these attributes be inserted into the activities of SMEs, and what were the impacts of defining a sustainability lens and inserting it into the strategy of three SMEs? Furthermore, there are many regions of the world where networks of SMEs have been found to create markets and unexpected synergies. Exploring these examples exposes the complexity of network formation and the architecture and behavior of such networks, but also produced some new understandings as examples of networking behavior from the Internet were contrasted with the performance of SME networks. It was found that networks of SMEs could form and dissolve rapidly; the term “ad hoc” network was coined to describe such behaviors. It was also observed that ad hoc networks could be extremely detrimental to the global physical and fiscal environments if their behaviors were not tempered by a realization of the need for sustainability and its associated behaviors. The globalization of markets seems to have forced SMEs to choose between hyperefficient behaviors, which create brittle, monofocused lowprice driven networks and have few environmental or social conscience boundaries, versus more resilient, socially, environmentally and financiallybounded networks that tend to be regional or local. The big questions addressed are whether SME networks can develop a hybrid structure that allows for adequate efficiency within a broadbased, “rightly understood” creation of value for large number of diverse stakeholders, and whether the winlose war of either “local” or “global” can be supplanted by multiscale sustainability? Samuel B. Moore, Erasmus University vi A transformative framework was developed based on the work of leading theorists on sustainable enterprise to encourage development of hybrid strategies and actions. This action research framework is outlined and consists of a series of educational and diagnostic exercises with the chosen firms, based on extensive dialogues with the owners/entrepreneurs of the firms. The anticipated results sought to balance the inputs and outputs of the corporation through inclusion of heretofore ignored stakeholders that creates new customers. The results were analyzed by value mapping of the new sustainable investments. This framework was used by the author on three SMEs as a lens to help the owners and managers of these firms to find a path forward out of their failing incumbent strategies. Three action research cases are presented: · Burlington Chemical Company, Inc. the author’s textile chemical manufacturing firm that was failing due to globalization of the textile industry. · Reedy Fork Dairy Farm – A family farm located in central North Carolina, USA that was failing due to wide fluctuation and decline of liquid milk prices. · TS Designs, Inc. A custom apparel printing company that was also failing due globalization of the textile market in the southeastern USA. The overall results of the action research projects were successful. Two of the three SMEs were adequately transformed as a result of sustainable lens insertion and new strategy implementation. They continue to survive and thrive after 5 plus years of strategic intervention. The textile chemical company did not survive due to inadequate understanding and actions related to “creative destruction” of the incumbent business model, however, even in failure, this case provides support for the idea that sustainable strategies can provide unique competitive advantages The finding of the research indicates that sustainability is a useful foundation for formal strategyplanning processes for SMEs. It forces consideration of internal and external factors and provides a new communication channel for communication and inclusion with new stakeholders. A sustainability lens provides for a broader definition of success that transcends but is inclusive of economic profitability and provides stability and control (resilience) within operations of SMES and networks of SMEs. The key concept of enterprise creating abundance for as many stakeholders as possible and thus expanding opportunities for many, rather than limiting value to strictly economic profits for shareholders, was a key metaphor for the success of these cases. Opportunities for further work remain in correlation of SME network behavior and other measureable networks such as the Internet. There also remains a great opportunity to study the resilience effects of the sustainability lens on creation of value for adopting SME firms and perhaps even the creation of new forms of SME network business structures

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented