We present an energy conscious location-aware computing system that provides relevant information about the users current location. The location-aware computing system is initialized with a map (in the form of a graph) as well as audio files associated with several locations in the map. The system consists of: GPS receiver module, Serial port, Compact flash module, Stereo codec, Power manager module implementing three sub modules namely, GPS-to-real-world position conversion module (implements algorithm to convert GPS co-ordinates to graph nodes), Nearest-location-search module (implements modified Dijkstras algorithm), and User speed estimation module. The location-aware computing system receives the GPS co-ordinates for the current location from GPS receiver through the serial port. The system converts the GPS co-ordinates to map co-ordinates stored in the Compact Flash card. If the current location matches the landmarks of interest in the site, then the relevant audio details of the current location is played out to the user. The power manager sets the GPS co-ordinates update frequency to avoid keeping the system component on throughout the entire course of travel. The power manager implements an algorithm that works as follows: at any given location, the algorithm predicts the user speed by exponential average approach. The attenuation factor of this approach can be varied to account for the user speed history. The estimated speed is used to predict the time (say T) required to reach the next nearest location determined by Nearest-location-search module implementing modified Dijkstras algorithm. The subsystems are shut-down or switched to low-power mode for time T. After time T, the system will wake up and re-execute the algorithm.

This thesis presents a novel self-powered infrastructural traffic monitoring approach that estimates traffic information by combining three detection techniques. The traffic information can be obtained from the presented approach includes vehicle counts, speed estimation and vehicle classification based on size. Two categories of sensors are used including IR Lidar and IR camera. With the two sensors, three detection techniques are used: Time of Flight (ToF) based, vision based and Laser spot flow based. Each technique outputs observations about vehicle location at different time step. By fusing the three observations in the framework of Kalman filter, vehicle location is estimated, based on which other concerned traffic information including vehicle counts, speed and class is obtained. In this process, high reliability is achieved by combing the strength of each techniques. To achieve self-powering, a dynamic power management strategy is developed to reduce system total energy cost and optimize power supply in traffic monitoring based on traffic pattern recognition. The power manager attempts to adjust the power supply by reconfiguring system setup according to its estimation about current traffic condition. A system prototype has been built and multiple field experiments and simulations were conducted to demonstrate traffic monitoring accuracy and power reduction efficacy. / Master of Science

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We present a generic proof methodology to automatically prove correctness of design transformations introduced at the Register-Transfer Level (RTL) to achieve lower power dissipation in hardware systems. We also introduce a new algorithm to reduce switching activity power dissipation in microprocessors. We further apply our technique in a completely different domain of dynamic power management of Systems-on-Chip (SoCs). We demonstrate our methodology on real-life circuits. In this thesis, we address the dual problem of transforming hardware systems at higher levels of abstraction to achieve lower power dissipation, and a reliable way to verify the correctness of the afore-mentioned transformations. The thesis is in three parts. The first part introduces Instruction-driven Slicing, a new algorithm to automatically introduce RTL/System level annotations in microprocessors to achieve lower switching power dissipation. The second part introduces Dedicated Rewriting, a rewriting based generic proof methodology to automatically prove correctness of such high-level transformations for lowering power dissipation. The third part implements dedicated rewriting in the context of dynamically managing power dissipation of mobile and hand-held devices. We first present instruction-driven slicing, a new technique for annotating microprocessor descriptions at the Register Transfer Level in order to achieve lower power dissipation. Our technique automatically annotates existing RTL code to optimize the circuit for lowering power dissipated by switching activity. Our technique can be applied at the architectural level as well, achieving similar power gains. We first demonstrate our technique on architectural and RTL models of a 32-bit OpenRISC pipelined processor (OR1200), showing power gains for the SPEC2000 benchmarks. These annotations achieve reduction in power dissipation by changing the logic of the design. We further extend our technique to an out-of-order superscalar core and demonstrate power gains for the same SPEC2000 benchmarks on architectural and RTL models of PUMA, a fixed point out-of-order PowerPC microprocessor. We next present dedicated rewriting, a novel technique to automatically prove the correctness of low power transformations in hardware systems described at the Register Transfer Level. We guarantee the correctness of any low power transformation by providing a functional equivalence proof of the hardware design before and after the transformation. Dedicated rewriting is a highly automated deductive verification technique specially honed for proving correctness of low power transformations. We provide a notion of equivalence and establish the equivalence proof within our dedicated rewriting system. We demonstrate our technique on a non-trivial case study. We show equivalence of a Verilog RTL implementation of a Viterbi decoder, a component of the DRM System-On-Chip (SoC), before and after the application of multiple low power transformations. We next apply dedicated rewriting to a broader context of holistic power management of SoCs. This in turn creates a self-checking system and will automatically flag conflicting constraints or rules. Our system will manage power constraint rules using dedicated rewriting specially honed for dynamic power management of SoC designs. Together, this provides a common platform and representation to seamlessly cooperate between hardware and software constraints to achieve maximum platform power optimization dynamically during execution. We demonstrate our technique in multiple contexts on an SoC design of the state-of-the-art next generation Intel smartphone platform. Finally, we give a proof of instruction-driven slicing. We first prove that the annotations automatically introduced in the OR1200 processor preserve the original functionality of the machine using the ACL2 theorem prover. Then we establish the same proof within our dedicated rewriting system, and discuss the merits of such a technique and a framework. In the context of today's shrinking hardware and mobile internet devices, lowering power dissipation is a key problem. Verifying the correctness of transformations which achieve that is usually a time-consuming affair. Automatic and reliable methods of verification that are easy to use are extremely important. In this thesis we have presented one such transformation, and a generic framework to prove correctness of that and similar transformations. Our methodology is constructed in a manner that easily and seamlessly fits into the design cycle of creating complicated hardware systems. Our technique is also general enough to be applied in a completely different context of dynamic power management of mobile and hand-held devices. / text

abstract: Semiconductor scaling technology has led to a sharp growth in transistor counts. This has resulted in an exponential increase on both power dissipation and heat flux (or power density) in modern microprocessors. These microprocessors are integrated as the major components in many modern embedded devices, which offer richer features and attain higher performance than ever before. Therefore, power and thermal management have become the significant design considerations for modern embedded devices. Dynamic voltage/frequency scaling (DVFS) and dynamic power management (DPM) are two well-known hardware capabilities offered by modern embedded processors. However, the power or thermal aware performance optimization is not fully explored for the mainstream embedded processors with discrete DVFS and DPM capabilities. Many key problems have not been answered yet. What is the maximum performance that an embedded processor can achieve under power or thermal constraint for a periodic application? Does there exist an efficient algorithm for the power or thermal management problems with guaranteed quality bound? These questions are hard to be answered because the discrete settings of DVFS and DPM enhance the complexity of many power and thermal management problems, which are generally NP-hard. The dissertation presents a comprehensive study on these NP-hard power and thermal management problems for embedded processors with discrete DVFS and DPM capabilities. In the domain of power management, the dissertation addresses the power minimization problem for real-time schedules, the energy-constrained make-span minimization problem on homogeneous and heterogeneous chip multiprocessors (CMP) architectures, and the battery aware energy management problem with nonlinear battery discharging model. In the domain of thermal management, the work addresses several thermal-constrained performance maximization problems for periodic embedded applications. All the addressed problems are proved to be NP-hard or strongly NP-hard in the study. Then the work focuses on the design of the off-line optimal or polynomial time approximation algorithms as solutions in the problem design space. Several addressed NP-hard problems are tackled by dynamic programming with optimal solutions and pseudo-polynomial run time complexity. Because the optimal algorithms are not efficient in worst case, the fully polynomial time approximation algorithms are provided as more efficient solutions. Some efficient heuristic algorithms are also presented as solutions to several addressed problems. The comprehensive study answers the key questions in order to fully explore the power and thermal management potentials on embedded processors with discrete DVFS and DPM capabilities. The provided solutions enable the theoretical analysis of the maximum performance for periodic embedded applications under power or thermal constraints. / Dissertation/Thesis / Ph.D. Computer Science 2012

Energy consumption has become a first-class optimization goal in design and implementation of data-intensive computing systems. This is particularly true in the design of database management systems (DBMS), which is one of the most important servers in software stack of modern data centers. Data storage system is one of the essential components of database and has been under many research efforts aiming at reducing its energy consumption. In previous work, dynamic power management (DPM) techniques that make real-time decisions to transition the disks to low-power modes are normally used to save energy in storage systems. In this research, we tackle the limitations of DPM proposals in previous contributions and design a dynamic energy-aware disk storage system in database servers. We introduce a DPM optimization model integrated with model predictive control (MPC) strategy to minimize power consumption of the disk-based storage system while satisfying given performance requirements. It dynamically determines the state of disks and plans for inter-disk data fragment migration to achieve desirable balance between power consumption and query response time. Furthermore, via analyzing our optimization model to identify structural properties of optimal solutions, a fast-solution heuristic DPM algorithm is proposed that can be integrated in large-scale disk storage systems, where finding the most optimal solution might be long, to achieve near-optimal power saving solution within short periods of computational time. The proposed ideas are evaluated through running simulations using extensive set of synthetic workloads. The results show that our solution achieves up to 1.65 times more energy saving while providing up to 1.67 times shorter response time compared to the best existing algorithm in literature. Stream join is a dynamic and expensive database operation that performs join operation in real-time fashion on continuous data streams. Stream joins, also known as window joins, impose high computational time and potentially higher energy consumption compared to other database operations, and thus we also tackle energy-efficiency of stream join processing in this research. Given that there is a strong linear correlation between energy-efficiency and performance of in-memory parallel join algorithms in database servers, we study parallelization of stream join algorithms on multicore processors to achieve energy efficiency and high performance. Equi-join is the most frequent type of join in query workloads and symmetric hash join (SHJ) algorithm is the most effective algorithm to evaluate equi-joins in data streams. To best of our knowledge, we are the first to propose a shared-memory parallel symmetric hash join algorithm on multi-core CPUs. Furthermore, we introduce a novel parallel hash-based stream join algorithm called chunk-based pairing hash join that aims at elevating data throughput and scalability. We also tackle parallel processing of multi-way stream joins where there are more than two input data streams involved in the join operation. To best of our knowledge, we are also the first to propose an in-memory parallel multi-way hash-based stream join on multicore processors. Experimental evaluation on our proposed parallel algorithms demonstrates high throughput, significant scalability, and low latency while reducing the energy consumption. Our parallel symmetric hash join and chunk-based pairing hash join achieve up to 11 times and 12.5 times more throughput, respectively, compared to that of state-of-the-art parallel stream join algorithm. Also, these two algorithms provide up to around 22 times and 24.5 times more throughput, respectively, compared to that of non-parallel (sequential) stream join computation where there is one processing thread.

Les applications temps réel modernes deviennent plus exigeantes en termes de ressources et de débit amenant la conception d'architectures multiprocesseurs. Ces systèmes, des équipements embarqués au calculateur haute performance, sont, pour des raisons d'autonomie et de fiabilité, confrontés des problèmes cruciaux de consommation d'énergie. Pour ces raisons, cette thèse propose de nouvelles techniques d'optimisation de la consommation d'énergie dans l'ordonnancement de systèmes multiprocesseur. La premiére contribution est un algorithme d'ordonnancement hiérarchique á deux niveaux qui autorise la migration restreinte des tâches. Cet algorithme vise á réduire la sous-optimalité de l'algorithme global EDF. La deuxiéme contribution de cette thèse est une technique de gestion dynamique de la consommation nommée Assertive Dynamic Power Management (AsDPM). Cette technique, qui régit le contrôle d'admission des tâches, vise á exploiter de manière optimale les modes repos des processeurs dans le but de réduire le nombre de processeurs actifs. La troisiéme contribution propose une nouvelle technique, nommée Deterministic Stretch-to-Fit (DSF), permettant d'exploiter le DVFS des processeurs. Les gains énergétiques observés s'approchent des solutions déjà existantes tout en offrant une complexité plus réduite. Ces techniques ont une efficacité variable selon les applications, amenant á définir une approche plus générique de gestion de la consommation appelée Hybrid Power Management (HyPowMan). Cette approche sélectionne, en cours d'exécution, la technique qui répond le mieux aux exigences énergie/performance.

Emerging mobile platforms integrate heterogeneous, multicore processors to efficiently deal with the heterogeneity of data (in magnitude, type, and quality). The main goal is to achieve a high degree of energy-proportionality which corresponds with the nature and fluctuation of mobile workloads. Most existing power and energy consumption analyses of these architectures rely on simulation or static benchmarks neither of which truly reflects the type of workload the processors handle in reality. By contrast, we generate two types of stochastic workloads and employ four types of dynamic voltage and frequency scaling (DVFS) policies to investigate the energy proportionality and the dynamic power consumption characteristics of a heterogeneous processor architecture when operating in different configurations. The analysis illustrates, both qualitatively and quantitatively, that knowledge of the statistics of the incoming workload is critical to determine the appropriate processor configuration.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-04T21:30:07Z No. of bitstreams: 1 DIÓGENES GALDINO GONDIM - DISSERTAÇÃO PPGCC 2014..pdf: 1586466 bytes, checksum: 3b6e47836d1098cd946a0d8486669b23 (MD5) / Made available in DSpace on 2018-04-04T21:30:07Z (GMT). No. of bitstreams: 1 DIÓGENES GALDINO GONDIM - DISSERTAÇÃO PPGCC 2014..pdf: 1586466 bytes, checksum: 3b6e47836d1098cd946a0d8486669b23 (MD5) Previous issue date: 2014-08-04 / A maioria dos sistemas operacionais oferecem suas próprias estratégias de gerenciamento de energia, mas é muito difícil modificar ou ampliar as políticas de energia sem acesso ao código fonte. Várias arquiteturas em gerenciamento dinâmico de energia já foram propostas na literatura, mas elas não são integradas com o sistema operacional subjacente. Neste trabalho, é proposto um arcabouço de software para o desenvolvimento de aplicações gerenciadoras de energia ao nível de usuário, com a flexibilidade arquitetural de se adaptar a diferentes políticas e de se integrar às políticas de gerenciamento do sistema operacional. Para validar o arcabouço, é descrito um estudo de caso mostrando sua viabilidade, demonstrando que a aplicação resultante oferece redução no consumo de energia. / Most operating systems implement their own power management techniques, but it is hard to modify or hack their power policies without the source code. Many dynamic power management architectures have been proposed in the literature, but they are not integrated with the underlying OS power manager. In this work, we proposed a software framework for user-level power management, with a flexible architecture to be adapted to different policies and integrated with OS power managers and validated its feasibility with a case study.

This term project deals with the problem of scheduling real-time tasks in overload conditions and techniques for lowering power consumption. Each of these parts features mechanisms and reasons for their using. There are also described specific algorithms, that are implemented, in operating system uC/OS-II, and compared in next phase of master's thesis.