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The storage hardware is evolving at a rapid pace to keep up with the exponential rise of data consumption. Recently, ultra-fast storage technologies such as nano-second scale byte- addressable Non-Volatile Memory (NVM), micro-second scale SSDs are being commercialized. However, the OS storage stack has not been evolving fast enough to keep up with these new ultra-fast storage hardware. Hence, the latency due user-kernel context switch caused by system calls and hardware interrupts is no longer negligible as presumed in the era of slower high latency hard disks. Further, the OS storage stack is not designed with multi-core scalability in mind; so with CPU core count continuously increasing, the OS storage stack particularly the Virtual Filesystem (VFS) and filesystem layer are increasingly becoming a scalability bottleneck. Applications bypass the kernel (kernel-bypass storage stack) completely to eliminate the storage stack from becoming a performance and scalability bottleneck. But this comes at the cost of programmability, isolation, safety, and reliability. Moreover, scalability bottlenecks in the filesystem can not be addressed by simply moving the filesystem to the userspace. Overall, while designing a kernel-bypass storage stack looks obvious and promising there are several critical challenges in the aspects of programmability, performance, scalability, safety, and reliability that needs to be addressed to bypass the traditional OS storage stack. This thesis proposes a series of kernel-bypass storage techniques designed particularly for fast memory-centric storage. First, this thesis proposes a scalable persistent transactional memory (PTM) programming model to address the programmability and multi-core scalability challenges. Next, this thesis proposes techniques to make the PTM memory safe and fault tolerant. Further, this thesis also proposes a kernel-bypass programming framework to port legacy DRAM-based in-memory database applications to run on persistent memory-centric storage. Finally, this thesis explores an application-driven approach to address the CPU side and storage side bottlenecks in the deep learning model training by proposing a kernel-bypass programming framework to move to compute closer to the storage. Overall, the techniques proposed in this thesis will be a strong foundation for the applications to adopt and exploit the emerging ultra-fast storage technologies without being bottlenecked by the traditional OS storage stack. / Doctor of Philosophy / The storage hardware is evolving at a rapid pace to keep up with the exponential rise of data consumption. Recently, ultra-fast storage technologies such as nano-second scale byte- addressable Non-Volatile Memory (NVM), micro-second scale SSDs are being commercialized. The Operating System (OS) has been the gateway for the applications to access and manage the storage hardware. Unfortunately, the OS storage stack that is designed with slower storage technologies (e.g., hard disk drives) becomes a performance, scalability, and programmability bottleneck for the emerging ultra-fast storage technologies. This has created a large gap between the storage hardware advancements and the system software support for such emerging storage technologies. Consequently, applications are constrained by the limitations of the OS storage stack when they intend to explore these emerging storage technologies. In this thesis, we propose a series of novel kernel-bypass storage stack designs to address the performance, scalability, and programmability limitations of the conventional OS storage stack. The kernel-bypass storage stack proposed in this thesis is carefully designed with ultra-fast modern storage hardware in mind. Application developers can leverage the kernel-bypass techniques proposed in this thesis to develop new applications or port the legacy applications to use the emerging ultra-fast storage technologies without being constrained by the limitations of the conventional OS storage stack.

Made available in DSpace on 2016-12-12T20:22:52Z (GMT). No. of bitstreams: 1 Eduardo B Viecilli.pdf: 12003318 bytes, checksum: 049902e80d65ca85726715d69e30469a (MD5) Previous issue date: 2014-03-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Mobile robots should be able to seek (explore the environment and recognize the objects) autonomously and efficiently. This work developed a mobile robot capable of performing the search for a 3D object in an unknown environment, using only one depth camera (RGB + Depth) as sensor and executing a strategy of active vision. The Microsoft Kinect was adopted as sensor. Also a mobile robot (XKBO) was build using the Robot Operating System (ROS), and with its architecture adapted from the norm STANAG 4586. A new active exploration strategy was developed in which considers the effort of the robot to move to the frontier regions (occult areas), and the presence of traces of the object. The metrics used demonstrated that the use of depth cameras for visual search tasks have a potential for deployment because associates visual and depth information, allowing the robot to better understand the environment and the target object of the search. / Robôs móveis devem ter a capacidade de buscar (explorar o ambiente e reconhecer objetos) de forma autônoma e eficiente. Este trabalho desenvolveu um robô móvel capaz de executar a busca a um objeto (3D) em ambiente desconhecido, utilizando somente uma câmera de profundidade (RGB + distancia) como sensor e executando uma estratégia de visão ativa. A Microsoft Kinect foi a câmera adotada. Também construiu-se um robô móvel (XKBO) que utiliza o Sistema Operacional Robótico (ROS), e com a arquitetura adaptada da norma STANAG 4586. Foi possível usar algoritmos existentes para reconhecer objetos 3D usando o Kinect graças as ferramentas presentes no ROS. E o uso do Kinect facilitou a geração de mapas do ambiente. Desenvolveu-se uma nova estratégia de exploração ativa que considera o esforço de movimentação para as regiões de fronteiras (áreas ocultas), e a existência de indícios da presença do objeto. As métricas utilizadas demonstram que o uso de câmeras de profundidade para tarefas de busca tem potencial para evolução por associar informação visuais com as de profundidade, permitindo que o robô possa entender o ambiente e o objeto alvo da busca. Palavras-chave: Robô Móvel. Exploração. Busca Visual. Câmera RGB-D.

Ett styrsystem för 3D-scanning har moderniserats av en projektgrupp på nio personer. Under utvecklingsarbetet följdes en arbetsprocess som liknade vattenfallsmetoden. Arbetsprocessen fungerade bra, bland annat då projektgruppen utnyttjat både tidigare och nya erfarenheter för att förbättra arbetssättet. Systemet som utvecklades ersätter ett tidigare styrsystem baserat på Matlab, men behåller samma grundläggande uppsättning hårdvara. En avståndskamera, en linjärenhet och ett rotationsbord utgör grunden till systemet. Med hjälp av denna hårdvara möjliggör systemet 3D-scanningar av mindre objekt. Styrsystemet är utvecklat med Python och ROS, Robot Operating System. Valet av ROS ledde till en komplex arkitektur på grund av skillnader i systemkrav hos ROS och hårdvarudrivrutiner. Utan dessa systemkrav tros ROS ha varit ett ypperligt val. Den utvecklade arkitekturen jämförs med en alternativ hypotetisk arkitektur, vilken uppvisade lägre komplexitet och större portabilitet. Den är dock inte lika lättanvänd tillsammans med andra ROS-system. Under utvecklingsarbetet har modularitet, vidareutvecklingsbarhet och robusthet varit i fokus. Även om det fullständiga systemet inte är så robust som önskats så anses de ingående modulerna uppvisa en önskad nivå av robusthet. Systemet uppvisar även en hög grad av modularitet. Den utförligt dokumenterade koden tillsammans med de väl separerade modulerna har lett till att systemet bör vara lätt att vidareutveckla.

Bakgrund: Konventionell röntgen, datortomografi (DT) och entrepreneurial operating system (EOS) är tre radiologiska undersökningsmetoder som kan användas för bilddiagnostik vid skolios av barn och ungdomar. Undersökningarna kan genomföras i en liggande eller stående positionering vid bedömning av ryggradens deformation. Dock avger dessa tre modaliteter joniserad strålning vid bildtagning. Syfte: Syftet med denna litteraturstudie var att jämföra konventionell röntgen, DT och EOS vid bilddiagnostik av skolios med fokus på barn och ungdomar. Metod: För att besvara syftet gjordes en litteraturstudie med systematisk ansats. Studier söktes databaserna Pubmed och Cinahl. Resultat: Två av tre studier påvisar att cobb-vinklen tenderar att minska från stående konventionella- och EOS-undersökningar till liggande DT-undersökningar. Vidare kan både DT och EOS generera 3D-rekonstruktioner för att underlätta bedömningen av deformationen. Den effektiva stråldosen går att reduceras för samtliga tre modaliteter men det finns en tendens att bildkvalitén försämras vid optimering. Slutsats: Konventionell röntgen, DT och EOS har för- och nackdelar avseende bilddiagnostik och stråldos. Samtliga tre modaliteter kan användas vid bedömning av ryggradens deformation och pre- och postoperativa bedömning, men det finns skillnader avseende stråldosen och bildkvalitén. Således krävs vidare forskning för att undersöka modaliteternas tillgänglighet och utifrån ett patientperspektiv. / Background: Conventional radiography, computed tomography (CT) and the entrepreneurial operating system (EOS) are three radiological examination methods that can be used for image diagnostics of scoliosis in children and adolescents. The examinations can be carried out in a lying or standing position when assessing the deformation of the spine. However, these three modalities emit ionizing radiation during imaging. Purpose: The purpose of this literature study was to compare conventional radiography, CT and EOS in imaging diagnostics of scoliosis with a focus on children and adolescents. Method: To answer the purpose, a systematic litteratur study was conducted. Literature were search for using the databases PubMed and Cinahl. Result: Two out of three studies showed that cobb-angle tends to decrsease from standning conventional and EOS examinations to lying CT examinations. Furthermore, both CT and EOS can generate 3D reconstuctions to facilitate the assessment of deformation. The effective radiation dose can be reduced for all three modalities, but there is a tendency for image quality to deteriorate during optimization. Conclusion: Conventional X-ray, CT and EOS have advantages and disadvantages in terms of imaging diagnosis and radiation dose. All three modalities can be applied for assessing spinal deformity and pre- and postoperative evaluations, but there are differences in image quality and radiation dose. Therefore, further research is required to investigate the accessibility of the modalities and their suitability from a patient perspective.

Thesis (MSc) -- Stellenbosch University, 2003. / ENGLISH ABSTRACT: Software testing tools simplify and automate the menial work associated with testing. Moreover, for complex concurrent software such as computer protocols, testing tools allow testing on an abstract level that is independent of specific implementations. Standard conformance testing methodologies and a number of testing tools are commercially available, but detailed descriptions of the implementation of such testing tools are not widely available. This thesis investigates the development of a tool for automated protocol testing in the ETH Oberon development environment. The need to develop a protocol testing tool that automates the execution of specified test cases was identified in collaboration with a local company that develops protocols in the programming language Oberon. Oberon is a strongly typed secure language that supports modularisation and promotes a readable programming style. The required tool should translate specified test cases into executable test code supported by a runtime environment. A test case consists of a sequence of input actions to which the software under test is expected to respond by executing observable output actions. A number of issues are considered of which the first is concerned with the representation of test case specifications. For this, a notation was used that is basically a subset of the test specification language TTCN-3 as standardised by the European Telecommunications Standards Institute. The second issue is the format of executable test cases and a suitable runtime environment. A translator was developed that generates executable Oberon code from specified test cases. The compiled test code is supported by a runtime library, which is part of the tool. Due to the concurrent nature of a protocol environment, concurrent processes in the runtime environment are identified. Since ETH Oberon supports multitasking in a limited sense, test cases are executed as cooperating background tasks. The third issue is concerned with the interaction between an executing test case and a system under test. It is addressed by an implementation dependent interface that maps specified test interactions onto real interactions as required by the test context in which an implementation under test operates. A supporting protocol to access the service boundary of an implementation under test remotely and underlying protocol service providers are part of a test context. The ETH Oberon system provides a platform that simplifies the implementation of protocol test systems, due to its size and simple task mechanism. Operating system functionality considered as essential is pointed out in general terms since other systems could be used to support such testing tools. In conclusion, directions for future work are proposed. / AFRIKAANSE OPSOMMING: Toetsstelsels vir programmatuur vereenvoudig en outomatiseer die slaafse werk wat met toetsing assosieer word. 'n Toetsstelsel laat verder toe dat komplekse gelyklopende programmatuur, soos rekenaarprotokolle, op 'n abstrakte vlak getoets word, wat onafhanklik van spesifieke implementasies is. Daar bestaan standaard metodes vir konformeringstoetsing en 'n aantal toetsstelsels is kommersiëel beskikbaar. Uitvoerige beskrywings van die implementering van sulke stelsels is egter nie algemeen beskikbaar nie. Hierdie tesis ondersoek die ontwikkeling van 'n stelsel vir outomatiese toetsing van protokolle in die ontwikkelingsomgewing van ETH Oberon. Die behoefte om 'n protokoltoetsstelsel te ontwikkel, wat die uitvoering van gespesifiseerde toetsgevalle outomatiseer, is geïdentifiseer in oorleg met 'n plaaslike maatskappy wat protokolle ontwikkel in die Oberon programmeertaal. Oberon is 'n sterkgetipeerde taal wat modularisering ondersteun en a leesbare programmeerstyl bevorder. Die toestsstelsel moet gespesifiseerde toetsgevalle vertaal na uitvoerbare toetskode wat ondersteun word deur 'n looptydomgewing. 'n Toetsgeval bestaan uit 'n reeks van toevoeraksies waarop verwag word dat die programmatuur wat getoets word, sal reageer deur die uitvoering van afvoeraksies wat waargeneem kan word. 'n Aantal kwessies word aangeraak, waarvan die eerste te make het met die voorstelling van die spesifikasie van toetsgevalle. Hiervoor is 'n notasie gebruik wat in wese 'n subversameling van die toetsspesifikasietaal TTCN-3 is. TTCN-3 is gestandardiseer deur die European Telecommunications Standards Institute. Die tweede kwessie is die formaat van uitvoerbare toetsgevalle en 'n geskikte looptydomgewing. 'n Vertaler is ontwikkel wat uitvoerbare Oberon-kode genereer vanaf gespesifiseerde toetsgevalle. Die vertaalde toetskode word ondersteun deur 'n biblioteek van looptydfunksies, wat deel van die stelsel is. As gevolg van die eienskap dat 'n protokolomgewing uit gelyklopende prosesse bestaan, word daar verskillende tipes van gelyklopende prosesse in 'n protokoltoetsstelsel geïdentifiseer. Aangesien ETH Oberon 'n beperkte multitaakstelsel is, word toetsgevalle vertaal na eindige outomate wat uitgevoer word as samewerkende agtergrondtake. Die derde kwessie het te make met die interaksie tussen 'n toetsgeval wat uitgevoer word en die stelsel wat getoets word. Dit word aangespreek deur 'n koppelvlak wat gespesifiseerde interaksies afbeeld op werklike interaksies soos vereis deur die konteks waarin 'n implementasie onderworpe aan toetsing uitvoer. 'n Ondersteunende protokolom die dienskoppelvlak van die implementasie oor 'n afstand te bereik en ander onderliggende protokoldienste is deel van 'n toetskonteks. Die ETH Oberon-stelsel help in die vereenvoudiging van die implementasie van protokol toetsstelsels, as gevolg van die stelsel se grootte en die eenvoudige taakhanteerder . Die essensiële funksionaliteit van bedryfsstelsels word uitgelig in algemene terme omdat ander stelsels gebruik kan word om toetsstelsels te ondersteun. Ten slotte word voorstelle vir opvolgwerk gemaak.

In dieser Arbeit wird die Möglichkeit der Unterstützung des Hardwareentwurfs mit VHDL durch ein Hardwarebetriebssystem untersucht. Durch die Wiederverwendung von Betriebssystemmodulen sollen die Entwicklungszeit verkürzt, die Nachnutzbarkeit von Entwürfen verbessert und die Zuverlässigkeit erhöht werden. Um ein Betriebssystemkonzept umzusetzen, müssen spezielle Anforderungen an die Programmiersprache gestellt werden. Diese werden von VHDL nicht erfüllt. Daher wird ein Strukturcompiler vorgestellt, der unter Beibehaltung der Syntax der Sprache VHDL den zusätzlichen Anforderungen gerecht wird. Der Strukturcompiler verbindet das Anwendungsprogramm mit den Betriebssystemmodulen und erzeugt daraus ein VHDL-Programm, das mit den typischen FPGA-Entwicklungswerkzeugen simuliert oder synthetisiert werden kann. Bei der Entwicklung des Betriebssystems für konfigurierbare Hardware hat sich herausgestellt, dass sich dieses nur eingebettet in ein Gesamtkonzept für den Entwurf von heterogene Systeme sinnvoll anwenden lässt. Deshalb wird in dieser Arbeit eine Methode für die Entwicklung von heterogenen Systemen auf Basis eines Signalflussgraphen diskutiert. Angewendet wurde das Betriebssystemkonzept auf verschiedenen FPGA-Karten, sowohl käuflich erworbene als auch Eigenentwicklungen. Das für diese Karten erstellte Betriebssystem umfasst dabei Module zur Kommunikation zwischen FPGA und PC sowie zur Anbindung verschiedener externer Peripheriegeräte, wie z.B. Speicher. Es wurde ebenfalls untersucht wie Prozessoren als Bestandteil der konfigurierbaren Hardware in das Betriebssystemkonzept integriert werden können. Im Rahmen dieser Arbeit wurden auch viele Beispielanwendungen untersucht. Diese wurden einerseits zum Testen des Strukturcompilers und der Betriebssystemmodule benutzt. Andererseits fand das Betriebssystemkonzept für konfigurierbare Hardware auch Anwendung in verschiedenen Projekten. / This work investigates the possibility of describing a hardware design independent of special hardware. This is realized with the concept of an operating system. The re-use of operating system modules reduces the time of development and also increases the reliability. Additionally, the change of a development platform has no influence on the application algorithm anymore. In order to apply the concept of an operating system special constraints have to be fulfilled by the hardware description language, which is not supported by VHDL. For that reason a structure compiler has been developed. The structure compiler connects the application program with the operating system modules and produces a VHDL program, which can be used to simulate or to program the FPGA with the typical VHDL development tools. In the progress of developing the operating system concept for reconfigurable hardware it was realized that such a concept can only be used in connection with a design methodology for heterogeneous systems. In this work a design methodology based on a declarative language represented as signal flow graph is discussed. The operating system concept for reconfigurable hardware was tested on different FPGA boards. For these cards an operating system was developed. The operating system contains modules for the communication with the PC over different interfaces as well as modules for accessing different exterior peripheries, i.e. memory. Additionally, the integration of processors as part of the configurable hardware within the operating system concept was investigated. For the verification of the structure compiler and the operating system modules some examples have been developed. The operating system concept for configurable hardware was also applied in different projects.

In order to improve the comfort of power wheelchair users, it is proposed in this dissertation the implementation of a position and orientation control system which allow the users to travel the desired trajectories safely, without the need for constant interaction with the device command system. To reach this objective, it is proposed a methodology for the implementation of a control system, able to drive the vehicle from an initial position to the desired one or make it follow a specified trajectory, from commands received in the system. The proposed control system is based on a cascade control law, composed by a nonlinear pose controller and a velocity tracking controller. Two velocity control strategies are proposed. The first one uses a velocity controller composed of two joint-independent Proportional-Integral controllers while the second one uses a velocity controller based on the dynamic model, which is linearized by a state-feedback. The methods are implemented using the ros_control package, provided by the framework Robot Operating System (ROS). The evaluation of the proposed methods is done with a differential-drive mobile robot, which has the same kinematic configuration as the majority of commercial power wheelchairs. The results of dynamic-model parameter identification, as well as the convergence of the controlled variables by using the proposed control methods, are presented. The results demonstrate that the methods achieve the proposed control objectives.

Based on a study of the engagement process between humans, I have developed models for four types of connection events involving gesture and speech: directed gaze, mutual facial gaze, adjacency pairs and backchannels. I have developed and validated a reusable Robot Operating System (ROS) module that supports engagement between a human and a humanoid robot by generating appropriate connection events. The module implements policies for adding gaze and pointing gestures to referring phrases (including deictic and anaphoric references), performing end-of-turn gazes, responding to human-initiated connection events and maintaining engagement. The module also provides an abstract interface for receiving information from a collaboration manager using the Behavior Markup Language (BML) and exchanges information with a previously developed engagement recognition module. This thesis also describes a Behavior Markup Language (BML) realizer that has been developed for use in robotic applications. Instead of the existing fixed-timing algorithms used with virtual agents, this realizer uses an event-driven architecture, based on Petri nets, to ensure each behavior is synchronized in the presence of unpredictable variability in robot motor systems. The implementation is robot independent, open-source and uses the Robot Operating System (ROS).