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Roth, Christopher. "A distributed password scheme for network operating systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FRoth.pdf.
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Gunaseelan, L. "Debugging of Distributed object systems." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/9219.
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Spafford, Eugene Howard. "Kernel structures for a distributed operating system." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/9144.
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Wentzlaff, David 1979. "dPool : a distributed data structure for factored operating systems." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71494.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 151-158).
Future computer architectures will likely exhibit increased parallelism through the addition of more processor cores. Architectural trends such as exponentially increasing parallelism and the possible lack of scalable shared memory motivate the reevaluation of operating system design. This thesis work takes place in the context of Factored Operating Systems which leverage distributed system ideas to increase the scalability of multicore processor operating systems. fos, a Factored Operating System, explores a new design point for operating systems where traditional low-level operating system services are fine-grain parallelized while internally only using explicit message passing for communication. fos factors an operating system first by system service and then further parallelizes inside of the system service by splitting the service into a fleet of server processes which communicate via messaging. Constructing parallel low-level operating system services which only internally use messaging is challenging because shared resources must be partitioned across servers and the services must provide scalable performance when met with uneven demand. To ease the construction of parallel fos system services, this thesis develops the dPool distributed data structure. The dPool data structure provides concurrent access to an unordered collection of elements by server processes within a fos fleet. Internal to a single dPool instance, all communication between different portions of a dPool is done via messaging. This thesis uses the dPool data structure within the parallel fos Physical Memory Allocation fleet and demonstrates that it is possible to use a dPool to manage shared state in a factored operating system's physical page allocator. This thesis begins by presenting the design of the prototype fos operating system. In the context of fos system service fleets, this thesis describes the dPool data structure, its design, different implementations, and interfaces. The dPool data structure is shown to achieve scalability across even and uneven micro-benchmark workloads. This thesis shows that common parallel and distributed programming techniques apply to the creation of dPool and that background threads within a dPool can increase performance. Finally, this thesis evaluates different dPool implementations and demonstrates that intelligently pushing elements between dPool parts can increase scalability.
by David Wentzlaff.
Ph.D.
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Turnbull, Martin John. "A design for a large scale distributed operating system." Thesis, University of Hertfordshire, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329070.
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Purdin, Titus Douglas Mahlon. "ENHANCING FILE AVAILABILITY IN DISTRIBUTED SYSTEMS (THE SAGUARO FILE SYSTEM)." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184161.
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This dissertation describes the design and implementation of the file system component of the Saguaro operating system for computers connected by a local-area network. Systems constructed on such an architecture have the potential advantage of increased file availability due to their inherent redundancy. In Saguaro, this advantage is made available through two mechanisms that support semi-automatic file replication and access: reproduction sets and metafiles. A reproduction set is a collection of files that the system attempts to keep identical on a "best effort" basis, relying on the user to handle unusual situations that may arise. A metafile is a special file that contains symbolic path names of other files; when a metafile is opened, the system selects an available constituent file and opens it instead. These mechanisms are especially appropriate for situations that do not require guaranteed consistency or a large number of copies. Other interesting aspects of the Saguaro file system design are also described. The logical file system forms a single tree, yet any file can be placed in any of the physical file systems. This organization allows the creation of a logical association among files that is quite different from their physical association. In addition, the broken path algorithm is described. This algorithm makes it possible to bypass elements in a path name that are on inaccessible physical file systems. Thus, any accessible file can be made available, regardless of the availability of directories in its path. Details are provided on the implementation of the Saguaro file system. The servers of which the system is composed are described individually and a comprehensive operational example is supplied to illustrate their interation. The underlying data structures of the file system are presented. The virtual roots, which contain information used by the broken path algorithm, are the most novel of these. Finally, an implementation of reproduction sets and metafiles for interconnected networks running Berkeley UNIX is described. This implementation demonstrates the broad applicability of these mechanisms. It also provides insight into the way in which mechanisms to facilitate user controlled replication of files can be inexpensively added to existing file systems. Performance measurements for this implementation are also presented.
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Stroud, Robert James. "Naming issues in the design of transparently distributed operating systems." Thesis, University of Newcastle Upon Tyne, 1987. http://hdl.handle.net/10443/1997.
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Naming is of fundamental importance in the design of transparently distributed operating systems. A transparently distributed operating system should be functionally equivalent to the systems of which it is composed. In particular, the names of remote objects should be indistinguishable from the names oflocal objects. In this thesis we explore the implication that this recursive notion of transparency has for the naming mechanisms provided by an operating system. In particular, we show that a recursive naming system is more readily extensible than a flat naming system by demonstrating that it is in precisely those areas in which a system is not recursive that transparency is hardest to achieve. However, this is not so much a problem of distribution so much as a problem of scale. A system which does not scale well internally will not extend well to a distributed system. Building a distributed system out of existing systems involves joining the name spaces of the individual systems together. When combining name spaces it is important to preserve the identity of individual objects. Although unique identifiers may be used to distinguish objects within a single name space, we argue that it is difficult if not impossible in practice to guarantee the uniqueness of such identifiers between name spaces. Instead, we explore the possibility of Using hierarchical identifiers, unique only within a localised context. However, We show that such identifiers cannot be used in an arbitrary naming graph without compromising the notion of identity and hence violating the semantics of the underlying system. The only alternative is to sacrifice a deterministic notion of identity by using random identifiers to approximate global uniqueness with a know probability of failure (which can be made arbitrarily small if the overall size of the system is known in advance).
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Wilkinson, Timothy James. "Implementing fault tolerance in a 64-bit distributed operating system." Thesis, City University London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356977.
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Murray, Kevin. "Wisdom : the foundation of a scalable parallel operating system." Thesis, University of York, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252628.
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Khalidi, M. Yousef Amin. "Hardware support for distributed object-based systems." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/8192.
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Kostkova, Patricie. "MAGNET - a dynamic resource management architecture." Thesis, City, University of London, 1999. http://discovery.ucl.ac.uk/10062371/.
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This thesis proposes a new dynamic resource management architecture, Magnet, to meet the requirements of users in flexible and adaptive systems. Computer systems no longer operate in centralized isolated static environments. Technological advances, such as smaller and faster hardware, and higher reliability of networks have resulted in the growth of mobility of computing and the need for run-time reconfigurability. The dynamic management of this diversity of resources is the central issue addressed in this thesis. Applications in environments with frequently changing characteristics are required to participate in dynamic resource management, to adapt to ever-changing conditions, and to express their requirements in terms of quality of service. Magnet enables dynamic trading of resources which can be requested indirectly by the type of service they offer, rather than directly by their name. A dedicated component, the Trader, matches requests for services against demands and establishes a component binding - resource allocation. In addition, the architecture is extensible - it does not constrain the information on services and allows user-customization of the matching process. Consequently, this allows resource definitions to be parametrized (to include QoS-based characteristics), and the matching process to be user-customized (to preform QoS-based negotiation). In order to fulfill the requirements of users relying on ever-changing conditions, Magnet enables runtime adaptation (dynamic rebinding) to changes in the environment, constant monitoring of resources, and scalability of the architecture. The generality of the Magnet architecture is illustrated with several examples of resource allocation in dynamic environments.
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Silcock, Jackie, and mikewood@deakin edu au. "Programmer friendly and efficient distributed shared memory integrated into a distributed operating system." Deakin University. School of Computing and Mathematics, 1998. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051114.110240.
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Distributed Shared Memory (DSM) provides programmers with a shared memory environment in systems where memory is not physically shared. Clusters of Workstations (COWs), an often untapped source of computing power, are characterised by a very low cost/performance ratio. The combination of Clusters of Workstations (COWs) with DSM provides an environment in which the programmer can use the well known approaches and methods of programming for physically shared memory systems and parallel processing can be carried out to make full use of the computing power and cost advantages of the COW.
The aim of this research is to synthesise and develop a distributed shared memory system as an integral part of an operating system in order to provide application programmers with a convenient environment in which the development and execution of parallel applications can be done easily and efficiently, and which does this in a transparent manner. Furthermore, in order to satisfy our challenging design requirements we want to demonstrate that the operating system into which the DSM system is integrated should be a distributed operating system.
In this thesis a study into the synthesis of a DSM system within a microkernel and client-server based distributed operating system which uses both strict and weak consistency models, with a write-invalidate and write-update based approach for consistency maintenance is reported. Furthermore a unique automatic initialisation system which allows the programmer to start the parallel execution of a group of processes with a single library call is reported. The number and location of these processes are determined by the operating system based on system load information.
The DSM system proposed has a novel approach in that it provides programmers with a complete programming environment in which they are easily able to develop and run their code or indeed run existing shared memory code. A set of demanding DSM system design requirements are presented and the incentives for the placement of the DSM system with a distributed operating system and in particular in the memory management server have been reported. The new DSM system concentrated on an event-driven set of cooperating and distributed entities, and a detailed description of the events and reactions to these events that make up the operation of the DSM system is then presented. This is followed by a pseudocode form of the detailed design of the main modules and activities of the primitives used in the proposed DSM system.
Quantitative results of performance tests and qualitative results showing the ease of programming and use of the RHODOS DSM system are reported. A study of five different application is given and the results of tests carried out on these applications together with a discussion of the results are given. A discussion of how RHODOS DSM allows programmers to write shared memory code in an easy to use and familiar environment and a comparative evaluation of RHODOS DSM with other DSM systems is presented. In particular, the ease of use and transparency of the DSM system have been demonstrated through the description of the ease with which a moderately inexperienced undergraduate programmer was able to convert, write and run applications for the testing of the DSM system. Furthermore, the description of the tests performed using physically shared memory shows that the latter is indistinguishable from distributed shared memory; this is further evidence that the DSM system is fully transparent. This study clearly demonstrates that the aim of the research has been achieved; it is possible to develop a programmer friendly and efficient DSM system fully integrated within a distributed operating system.
It is clear from this research that client-server and microkernel based distributed operating system integrated DSM makes shared memory operations transparent and almost completely removes the involvement of the programmer beyond classical activities needed to deal with shared memory. The conclusion can be drawn that DSM, when implemented within a client-server and microkernel based distributed operating system, is one of the most encouraging approaches to parallel processing since it guarantees performance improvements with minimal programmer involvement.
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De, Paoli Damien, and mikewood@deakin edu au. "Multiple strategy process migration." Deakin University. School of Computing and Mathematics, 1996. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051110.115628.
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The future of computing lies with distributed systems, i.e. a network of workstations controlled by a modern distributed operating system. By supporting load balancing and parallel execution, the overall performance of a distributed system can be improved dramatically. Process migration, the act of moving a running process from a highly loaded machine to a lightly loaded machine, could be used to support load balancing, parallel execution, reliability etc.
This thesis identifies the problems past process migration facilities have had and determines the possible differing strategies that can be used to resolve these problems. The result of this analysis has led to a new design philosophy. This philosophy requires the design of a process migration facility and the design of an operating system to be conducted in parallel.
Modern distributed operating systems follow the microkernel and client/server paradigms. Applying these design paradigms, in conjunction with the requirements of both process migration and a distributed operating system, results in a system where each resource is controlled by a separate server process. However, a process is a complex resource composed of simple resources such as data structures, an address space and communication state. For this reason, a process migration facility does not directly migrate the resources of a process. Instead, it requests the appropriate servers to transfer the resources. This novel solution yields a modular, high performance facility that is easy to create, debug and maintain. Furthermore, the design easily incorporates providing multiple migration strategies.
In order to verify the validity of this design, a process migration facility was developed and tested within RHODOS (ResearcH Oriented Distributed Operating System). RHODOS is a modern microkernel and client/server based distributed operating system. In RHODOS, a process is composed of at least three separate resources: process state - maintained by a process manager, address space - maintained by a memory manager and communication state - maintained by an InterProcess Communication Manager (IPCM). The RHODOS multiple strategy migration manager utilises the services of the process, memory and IPC Managers to migrate the resources of a process. Performance testing of this facility indicates that this design is as fast or better than existing systems which use faster hardware. Furthermore, by studying the results of the performance test
ing, the conditions under which a particular strategy should be employed have been identified.
This thesis also addresses heterogeneous process migration. The current trend is to have islands of homogeneous workstations amid a sea of heterogeneity. From this situation and the current literature on the topic, heterogeneous process migration can be seen as too inefficient for general use. Instead, only homogeneous workstations should be used for process migration. This implies a need to locate homogeneous workstations. Entities called traders, which store and disseminate knowledge about the resources of several workstations, should be used to provide resource discovery. Resource discovery will enable the detection of homogeneous workstations to which processes can be migrated.
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Deorukhkar, Mayuresh. "Deadlock probability prediction and detection in distributed systems /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1421130.
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Messer, Alan. "A market model for controlled resource allocation in distributed operating systems." Thesis, City, University of London, 1999. http://openaccess.city.ac.uk/20134/.
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This thesis explores the potential for providing processes with control over their resource allocation in a general-purpose distributed system. Rather than present processes with blind explicit control or leave the decision to the operating system, a compromise, called process-centric resource allocation is proposed whereby processes have informed control of their resource allocation, while the operating system ensures fair consumption. The motivations for this approach to resource allocation and its background are reviewed culminating in the description of a set of desired attributes for such a system. A three layered architecture called ERA is then proposed and presented in detail. The lowest layer, provides a unified framework for processes to choose resources, describe their priority and describes the range of available resources. A resource information mechanism, used to support choices of distributed resources then utilises this framework. Finally, experimental demonstrations of process-centric resource allocation are used to illustrate the third layer. This design and its algorithms together provide a resource allocation system wherein distributed resources are shared fairly amongst competing processes which can choose their resources. The system allows processes to mimic traditional resource allocations and perform novel and beneficial resource optimisations. Experimental results are presented indicating that this can be achieved with low overhead and in a scalable fashion.
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Bazzi, Rida Adnan. "Automatically increasing fault tolerance in distributed systems." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/8133.
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Wang, Xiaolong. "A Secure Computing Platform for Building Automation Using Microkernel-based Operating Systems." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7589.
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Building Automation System (BAS) is a complex distributed control system that is widely deployed in commercial, residential, industrial buildings for monitoring and controlling mechanical/electrical equipment. Through increasing industrial and technological advances, the control components of BAS are becoming increasingly interconnected. Along with potential benefits, integration also introduces new attack vectors, which tremendous increases safety and security risks in the control system. Historically, BAS lacks security design and relies on physical isolation and "security through obscurity". These methods are unacceptable with the "smart building" technologies. The industry needs to reevaluate the safety and security of the current building automation system, and design a comprehensive solution to provide integrity, reliability, and confidentiality on both system and network levels.
This dissertation focuses on the system level in the effort to provide a reliable computing foundation for the devices and controllers. Leveraged on the preferred security features such as, robust modular design, small privilege code, and formal verifiability of microkernel architecture, this work describes a security enhanced operating system with built-in mandatory access control and a proxy-based communication framework for building automation controllers. This solution ensures policy-enforced communication and isolation between critical applications and non-critical applications in a potentially hostile cyber environment.
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Swim, Bradley Roy. "Predictable dynamic task scheduling in a hard real-time distributed operating system." Thesis, Staffordshire University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337215.
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Johnston, Ryan Andrew. "Obtaining high performance phasor measurements in a geographically distributed status dissemination network." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Summer2005/r%5Fjohnston%5F072905.pdf.
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Wang, Koping. "Spider II: A component-based distributed computing system." CSUSB ScholarWorks, 2001. https://scholarworks.lib.csusb.edu/etd-project/1874.
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Spider II system is the second version implementation of the Spider project. This system is the first distributed computation research project in the Department of Computer Science at CSUSB. Spider II is a distributed virtual machine on top of the UNIX or LINUX operating system. Spider II features multi-tasking, load balancing and fault tolerance, which optimize the performance and stability of the system.
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Mukherjee, Bodhisattwa. "Reconfigurable multiprocessor operating system kernel for high performance computing." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/9120.
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Zhu, Wenzhang. "Distributed JAVA virtual machine with thread migration /." View the Table of Contents & Abstract, 2004. http://sunzi.lib.hku.hk/hkuto/record/B30396773.
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Zhu, Wenzhang, and 朱文章. "Distributed JAVA virtual machine with thread migration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B45015260.
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Krishnaswamy, Vijaykumar. "Shared state management for time-sensitive distributed applications." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/8197.
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Sjöström, Thames Sixten. "Porting a Real-Time Operating System to a Multicore Platform." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76933.
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This thesis is part of the European MANY project. The goal of MANY is to provide developers with tools to develop software for multi and many-core hardware platforms. This is the first thesis that is part of MANY at Enea. The thesis aims to provide a knowledge base about software on many-core at the Enea student research group. More than just providing a knowledge base, a part of the thesis is also to port Enea's operating system OSE to Tilera's many-core processor TILEpro64. The thesis shall also investigate the memory hierarchy and interconnection network of the Tilera processor. The knowledge base about software on many-core was constrained to investigating the shared memory model and operating systems for many-core. This was achieved by investigating prominent academic research about operating systems for many-core processors. The conclusion was that a shared memory model does not scale and for the operating system case, operating systems shall be designed with scalability as one of the most important requirements. This thesis has implemented the hardware abstraction layer required to execute a single-core version of OSE on the TILEpro architecture. This was done in three steps. The Tilera hardware and the OSE software platform were investigated. After that, an OSE target port was chosen as reference architecture. Finally, the hardware dependent parts of the reference software were modified. A foundation has been made for future development.
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Baunach, Marcel [Verfasser], and Reiner [Akademischer Betreuer] Kolla. "Advances in Distributed Real-Time Sensor/Actuator Systems Operation - Operating Systems, Communication, and Application Design Concepts - / Marcel Baunach. Betreuer: Reiner Kolla." Würzburg : Universitätsbibliothek der Universität Würzburg, 2013. http://d-nb.info/103163083X/34.
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Böke, Carsten. "Automatic configuration of real time operating systems and real time communication systems for distributed embedded applications." Paderborn : Heinz-Nixdorf-Inst, 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971712182.
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Chelliah, Muthusamy. "Support for fault-tolerant computations in distributed object systems." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8483.
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McDonald, Ian Lindsay. "Memory management in a distributed system of single address space operating systems supporting quality of service." Thesis, University of Glasgow, 2001. http://theses.gla.ac.uk/5427/.
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The choices provided by an operating system to the application developer for managing memory came in two forms: no choice at all, with the operating system making all decisions about managing memory; or the choice to implement virtual memory management specific to the individual application. The second of these choices is, for all intents and purposes, the same as the first: no choice at all. For many application developers, the cost of implementing a customised virtual memory management system is just too high. The results is that, regardless of the level of flexibility available, the developer ends up using the system-provided default. Further exacerbating the problem is the tendency for operating system developers to be extremely unimaginative when providing that same default. Advancements in virtual memory techniques such as prefetching, remote paging, compressed caching, and user-level page replacement coupled with the provision of user-level virtual memory management should have heralded a new era of choice and an application-centric approach to memory management. Unfortunately, this has failed to materialise. This dissertation describes the design and implementation of the Heracles virtual memory management system. The Heracles approach is one of inclusion rather than exclusion. The main goal of Heracles is to provide an extensible environment that is configurable to the extent of providing application-centric memory management without the need for application developers to implement their own. However, should the application developer wish to provide a more specialised implementation for all or any part of Heracles, the system is constructed around well-defined interfaces that allow new implementations to be "plugged in" where required. The result is a virtual memory management hierarchy that is highly configurable, highly flexible, and can be adapted at run-time to meet new phases in the application's behaviour. Furthermore, different parts of an application's address space can have different hierarchies associated with managing its memory.
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Bhola, Sumeer Kumar. "Replication in interactive distributed applications : abstractions, algorithms and evaluation." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8138.
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Yuh, Han-Sheng. "Spider: An overview of an object-oriented distributed computing system." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/1417.
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Boone, Gary Noel. "Extreme dimensionality reduction for text learning : cluster-generated feature spaces." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/8139.
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Bor, Mehmet. "Effective interprocess communication (IPC) in a real-time transputer network." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/33101.
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The thesis describes the design and implementation of an interprocess communication (IPC) mechanism within a real-time distributed operating system kernel (RT-DOS) which is designed for a transputer-based network. The requirements of real-time operating systems are examined and existing design and implementation strategies are described. Particular attention is paid to one of the object-oriented techniques although it is concluded that these techniques are not feasible for the chosen implementation platform. Studies of a number of existing operating systems are reported. The choices for various aspects of operating system design and their influence on the IPC mechanism to be used are elucidated. The actual design choices are related to the real-time requirements and the implementation that has been adopted is described.
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McLean, Angus L. M. Thom III. "Real-time distributed simulation analysis : an application of temporal database and simulation systems research." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/9124.
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Apte, Manoj Shriganesh. "An operating system architecture and hybrid scheduling methodology for real-time systems with uncertainty." Diss., Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-11102004-152431.
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Topol, Brad Byer. "A framework for the development of wide area distributed applications." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/8300.
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Lin, Chu-chung. "The design of a distributed debugger for action-based object-oriented programs." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/8205.
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Rappin, Noel. "A framework for teaching learners to model by focusing complexity of modeling and simulation tools." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/8248.
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Barcellos, Antonio Marinho Pilla. "O sistema operacional de rede heterogêneo HetNOS." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1993. http://hdl.handle.net/10183/25456.
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O advento dos computadores pessoais e posteriormente das estações de trabalho, somado ao desenvolvimento de hardware de comunicação eficiente e de baixo custo, levou a popularização das redes locais. Entretanto, o software não presenciou o mesmo desenvolvimento do hardware, especialmente devido a complexidade dos sistemas distribuídos. A heterogeneidade das máquinas, sistemas e redes, inerente aos ambientes computacionais modernos, restringe igualmente a integração e cooperação entre os nodos disponíveis. 0 objetivo do presente trabalho é, a partir da análise dos principais aspectos relacionados à distribuição e à heterogeneidade, desenvolver um sistema operacional de rede heterogêneo. Tal sistema, denominado HetNOS (de Heterogeneous Network Operating System), permite o desenvolvimento e validação de aplicações distribuídas homogêneas e heterogêneas de forma rápida e fácil. Os usuários podem concentrar-se nos aspectos de distribuição dos algoritmos, abstraindo detalhes dos mecanismos de comunicação, pois a programação de aplicações distribuídas é baseada em uma plataforma de interface homogênea, fácil de usar e com independência de localidade. Sendo um sistema operacional de rede, o HetNOS atua sobre o conjunto de sistemas operacionais nativos existentes; o ambiente de trabalho e estendido e não substituído. Não há entidades nem informações centralizadas, e os algoritmos são distribuídos, usualmente resultando maior confiabilidade e desempenho. A topologia do sistema é um anel lógico, esquema justificado pela generalidade de tal configuração e pela simplificação do projeto do núcleo distribuído do HetNOS. O paradigma de comunicação entre módulos e a troca de mensagens, mecanismo implementado sobre a interface de programação em rede sockets. Não há compartilhamento de memória em nenhuma instância, tornando o sistema mais legível, manutenível e portável. A interpelação entre módulos fica restrita à interface de mensagens definidas e aceitas por cada módulo. A arquitetura do HetNOS é estruturada e distribuída, pois o sistema é composto de camadas hierárquicas subdivididas em módulos, estes implementados com processos. O nível 1 corresponde ao conjunto de núcleos de sistemas operacionais nativos suportados, sobre o qual é implementado o núcleo distribuído heterogêneo do HetNOS, a DCL (Distributed Computing Layer). O principal serviço fornecido pela DCL (executada no nível 2), é um subsistema de troca de mensagens canônico e independente de localidade. Processos servidores e de usuários podem utilizar as mais variadas formas de comunicação por mensagens, tal como envio, recepção e propagação de mensagens síncronas, assíncronas, bloqueantes e não bloqueantes. No nível 3 estão os servidores do sistema, que estendem e implementam de forma distribuída a funcionalidade do sistema nativo. O Servidor de Nomes é o repositório global de dados, servindo a processos do sistema e de usuários. O Servidor de Autorização implementa o esquema de controle no acesso a recursos do sistema. O Servidor de Tipos permite que aplicações copiem dados estruturados de forma independente de localidade e de arquitetura. Por fim, o Servidor de Arquivos estende os serviços (de arquivos) locais de forma a integrá-los em um único domínio (espaço). No nível 4, arquiteturas e sistemas operacionais são emulados por módulos interpretadores (denominados Emulators). Aplicações de usuários estão espalhadas dos níveis 2 a 5; a camada varia com o tipo de aplicação. Para demonstrar a viabilidade do sistema, implementou-se a estrutura fundamental do HetNOS, incluindo a DCL (um núcleo distribuído heterogêneo), a versões básicas dos módulos servidores, as bibliotecas de procedimentos, além de diversos tipos de aplicações. O sistema conta hoje com mais de 25.000 linhas de código fonte C em mais de 100 arquivos. O desempenho do subsistema de comunicação implementado pela DCL (em avaliações com diferentes configurações de hardware) superou as expectativas iniciais, mas ainda está muito aquém do necessário a aplicações distribuídas. Segundo o que indicam as primeiras experiências realizadas, o HetNOS será bastante útil na prototipação e avaliação de modelos distribuídos, assim como na programação de software distribuído homogêneo e heterogêneo. Projetos de pesquisa do CPGCC envolvendo sistemas distribuídos (p.ex., tolerância a falhas e simulações) podem utilizar o HetNOS como ferramenta para implementação e validação de seus modelos. Futuramente, aplicações distribuídas e paralelas de maior porte poderão ser programadas, como sistemas de gerencia de bases de dados distribuídas, simuladores e sistemas de controle para automação industrial.The advent of personal computers and, later, of workstations, along with the development of efficient and low-cost communication hardware has led to the popularization of local-area networks. However, distributed software did not experiment the same development of hardware, specially due to the complexity of distributed systems. The machine, system and communication network heterogeneity, inherent to the modern computing environments, is also responsible for the lack of integration and cooperation of available nodes. The purpose of this work is, from the analysis of the main aspects related to distribution and heterogeneity, to design a heterogeneous network operating system. Such system, named HetNOS (which stands for Heterogeneous Network Operating System), allows users to quickly write and validate distributed homogeneous and heterogeneous applications. Users can concentrate their work in the distributed aspects, abstracting communication mechanisms' details, because programming of distributed applications is based on a homogeneous interface platform, easy to use and location-independent. Being a network operating system, HetNOS acts over the set of native operating systems; the environment is extended instead of substituted. There are neither centralized information nor entities, and the algorithms are always distributed, usually yielding more reliability and performance. The HetNOS topology is a logical ring, scheme adopted partly due to the generality of such configuration and partly to simplify the HetNOS distributed kernel design. The communication paradigm between modules is the message exchange, a mechanism implemented over the sockets network application programming interface. There is no shared memory at all, making the system clearer, more manutible and portable. The interrelation between modules is restricted to the message interface defined and accepted by a module. The HetNOS architecture is structured and distributed, as the system is composed of hierarchical layers divided into modules, which in their turn are realized as processes. The layer 1 is the set of native operating system kernels, over which is implemented the distributed heterogeneous HetNOS kernel, namely DCL (states for Distributed Computing Layer). The main service provided by DCL (in layer 2) is a canonical, location-independent, message exchange mechanism. Server and user processes may use multiple forms of message primitives, such as synchronous, asynchronous, blocking and non-blocking send and receive. In the layer 3 are the system servers, which extend and implement in a distributed way the functionality of native systems. The name server is a global data repository, serving other system and user processes. The authorization server implements the security scheme to control the access to the system resources. The type server allows applications to transfer structured data independently of location and architecture. Finally, the file server extends the local (file) services to integrate them into a unique domain (space). In the layer 4, architectures and operating systems are emulated by interpreter modules (named Emulators). User applications are spread over the layers 2 to 5, depending on the application type. In order to prove the system viability, the fundamental HetNOS structure has been implemented, including its distributed heterogeneous kernel, the base of server modules, the procedure libraries, and several types of applications. The system source code has over 25,000 lines of C programming distributed over a hundred files. Although the optimization is an endless process, the performance of the DCL communication subsystem (evaluated using a few different hardware configurations) overestimated initial predictions, but is weak if considered the requirements to distributed processing. Accordingly to the first experiences made, HetNOS will be of great value to evaluate and prototype distributed models, as well as to the programming of homogeneous and heterogeneous distributed software. Local research projects involving distributed systems (e.g., fault tolerance and simulations) may use HetNOS as a tool to validate and implement their models. In the future, more complex distributed and parallel applications will be programmed, such as a distributed database management system, simulators and factory automation control systems.
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Brogan, David C. "Simulation levels of detail for control and animation." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/8142.
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Tauber, Markus. "Autonomic management in a distributed storage system." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/926.
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Gong, Guohui. "On concurrency control in logbased databases." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8175.
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Meuter, Cédric. "Development and validation of distributed reactive control systems." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210552.
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A reactive control system is a computer system reacting to certain stimuli emitted by its environment in order to maintain it in a desired state. Distributed reactive control systems are generally composed of several processes, running in parallel on one or more computers, communicating with one another to perform the required control task. By their very nature, distributed reactive control systems are hard to design. Their distributed nature and/or the communication scheme used can introduce subtle unforeseen behaviours. When dealing with critical applications, such as plane control systems, or traffic light control systems, those unintended behaviours can have disastrous consequences. It is therefore essential, for the designer, to ensure that this does not happen. For that purpose, rigorous and systematic techniques can (and should) be applied as early as possible in the development process. In that spirit, this work aims at providing the designer with the necessary tools in order to facilitate the development and validation of such distributed reactive control systems. In particular, we show how using a dedicated language called dSL (Distributed Supervision language) can be used to ease the development process. We also study how validations techniques such as model-checking and testing can be applied in this context.Doctorat en Sciences
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Schaefer, Linda Ruth. "Analysis of a coordination framework for mapping coarse-grain applications to distributed systems." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4270.
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A paradigm is presented for the parallelization of coarse-grain engineering and scientific applications. The coordination framework provides structure and an organizational strategy for a parallel solution in a distributed environment. Three categories of primitives which define the coordination framework are presented: structural, transformational. and operational. The prototype of the paradigm presented in this thesis is the first step towards a programming development tool. This tool will allow non-specialist programmers to parallelize existing sequential solutions through the distribution, synchronization and collection of tasks. The distributed control, multidimensional pipeline characteristics of the paradigm provide advantages which include load balancing through the use of self-directed workers, a simplified communication scheme ideally suited for infrequent task interaction, a simple programmer interface, and the ability of the programmer to use already existing code. Results for the parallelization of SPICE3Cl in a distributed system of fifteen SUN 3 workstations with one fileserver demonstrate linear speedup with slopes ranging from 0.7 to 0.9. A high-level abstraction of the system is presented in the form of a closed, single class, queuing network model. Using the Mean Value Analysis solution technique from queuing network theory, an expression for total execution time is obtained and is shown to be consistent with the well known Amdahl's Law. Our expression is in fact a refinement of Amdahl's Law which realistically captures the limitations of the system. We show that the portion of time spent executing serial code which cannot be enhanced by parallelization is a function of N, the number of workers in the system. Experiments reveal the critical nature of the communication scheme and the synchronization of the paradigm. Investigation of the synchronization center indicates that as N increases, visitations to the center increase and degrade system performance. Experimental data provides the information needed to characterize the impact of visitations on the perfoimance of the system. This characterization provides a mechanism for optimizing the speedup of an application. It is shown that the model replicates the system as well as predicts speedup over an extended range of processors, task count, and task size.
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Reid, Jason Frederick. "Enhancing security in distributed systems with trusted computing hardware." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16379/.
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The need to increase the hostile attack resilience of distributed and internet-worked computer systems is critical and pressing. This thesis contributes to concrete improvements in distributed systems trustworthiness through an enhanced understanding of a technical approach known as trusted computing hardware. Because of its physical and logical protection features, trusted computing hardware can reliably enforce a security policy in a threat model where the authorised user is untrusted or when the device is placed in a hostile environment.
We present a critical analysis of vulnerabilities in current systems, and argue that current industry-driven trusted computing initiatives will fail in efforts to retrofit security into inherently flawed operating system designs, since there is no substitute for a sound protection architecture grounded in hardware-enforced domain isolation. In doing so we identify the limitations of hardware-based approaches. We argue that the current emphasis of these programs does not give sufficient weight to the role that operating system security plays in overall system security. New processor features that provide hardware support for virtualisation will contribute more to practical security improvement because they will allow multiple operating systems to concurrently share the same processor. New operating systems that implement a sound protection architecture will thus be able to be introduced to support applications with stringent security requirements. These can coexist alongside inherently less secure mainstream operating systems, allowing a gradual migration to less vulnerable alternatives.
We examine the effectiveness of the ITSEC and Common Criteria evaluation and certification schemes as a basis for establishing assurance in trusted computing hardware. Based on a survey of smart card certifications, we contend that the practice of artificially limiting the scope of an evaluation in order to gain a higher assurance rating is quite common. Due to a general lack of understanding in the marketplace as to how the schemes work, high evaluation assurance levels are confused with a general notion of 'high security strength'. Vendors invest little effort in correcting the misconception since they benefit from it and this has arguably undermined the value of the whole certification process.
We contribute practical techniques for securing personal trusted hardware devices against a type of attack known as a relay attack. Our method is based on a novel application of a phenomenon known as side channel leakage, heretofore considered exclusively as a security vulnerability. We exploit the low latency of side channel information transfer to deliver a communication channel with timing resolution that is fine enough to detect sophisticated relay attacks. We avoid the cost and complexity associated with alternative communication techniques suggested in previous proposals. We also propose the first terrorist attack resistant distance bounding protocol that is efficient enough to be implemented on resource constrained devices.
We propose a design for a privacy sensitive electronic cash scheme that leverages the confidentiality and integrity protection features of trusted computing hardware. We specify the command set and message structures and implement these in a prototype that uses Dallas Semiconductor iButtons.
We consider the access control requirements for a national scale electronic health records system of the type that Australia is currently developing. We argue that an access control model capable of supporting explicit denial of privileges is required to ensure that consumers maintain their right to grant or withhold consent to disclosure of their sensitive health information in an electronic system. Finding this feature absent in standard role-based access control models, we propose a modification to role-based access control that supports policy constructs of this type. Explicit denial is difficult to enforce in a large scale system without an active central authority but centralisation impacts negatively on system scalability. We show how the unique properties of trusted computing hardware can address this problem. We outline a conceptual architecture for an electronic health records access control system that leverages hardware level CPU virtualisation, trusted platform modules, personal cryptographic tokens and secure coprocessors to implement role based cryptographic access control. We argue that the design delivers important scalability benefits because it enables access control decisions to be made and enforced locally on a user's computing platform in a reliable way.
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Werner, Matthias. "Verteilte Mobilität - Eine spannende Herausforderung." Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-78213.
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Cyber-physikalische Systeme (CPS) sind eine erweitere Sicht auf eingebettete Systeme, die die konkreten umgebenden Elemente in das Systemdesign einbeziehen. Das Design solcher Systeme erfordert neue Herangehensweisen: Während beispielsweise in "normalen" verteilten Systemen Aspekte wie "Bewegung" oder "Ort" möglichst transparent und damit für den Nutzer unsichtbar gestaltet werden, benötigen CPS-Anwendungen häufig Bewusstsein für Bewegung oder Ort, d.h., sie sind _motion aware_ oder _location aware_.
Die Professur "Betriebssysteme" der TUC hat sich die Frage gestellt, wie eine generische Unterstützung für solche verteilte mobile Systeme aussehen könnte. Im Vortrag werden Probleme, Konzepte und erste Lösungsansätze für ein künftiges Betriebssystem für diese Art von Systemen vorgestellt.
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Hutchins, Ronald Roscoe. "Internet user access via dial-up and campus wireless networks-tracffic characterization and statistics." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/8186.
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Hoffman, P. Kuyper. "A file server for the DistriX prototype : a multitransputer UNIX system." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/17188.
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Bibliography: pages 90-94.The DISTRIX operating system is a multiprocessor distributed operating system based on UNIX. It consists of a number of satellite processors connected to central servers. The system is derived from the MINIX operating system, compatible with UNIX Version 7. A remote procedure call interface is used in conjunction with a system wide, end-to-end communication protocol that connects satellite processors to the central servers. A cached file server provides access to all files and devices at the UNIX system call level. The design of the file server is discussed in depth and the performance evaluated. Additional information is given about the software and hardware used during the development of the project. The MINIX operating system has proved to be a good choice as the software base, but certain features have proved to be poorer. The Inmos transputer emerges as a processor with many useful features that eased the implementation.
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John, Ranjit. "Implementing and programming weakly consistent memories." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/12890.
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Yang, Baoyao. "Distribution alignment for unsupervised domain adaptation: cross-domain feature learning and synthesis." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/556.
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In recent years, many machine learning algorithms have been developed and widely applied in various applications. However, most of them have considered the data distributions of the training and test datasets to be similar. This thesis concerns on the decrease of generalization ability in a test dataset when the data distribution is different from that of the training dataset. As labels may be unavailable in the test dataset in practical applications, we follow the effective approach of unsupervised domain adaptation and propose distribution alignment methods to improve the generalization ability of models learned from the training dataset in the test dataset. To solve the problem of joint distribution alignment without target labels, we propose a new criterion of domain-shared group sparsity that is an equivalent condition for equal conditional distribution. A domain-shared group-sparse dictionary learning model is built with the proposed criterion, and a cross-domain label propagation method is developed to learn a target-domain classifier using the domain-shared group-sparse representations and the target-specific information from the target data. Experimental results show that the proposed method achieves good performance on cross-domain face and object recognition. Moreover, most distribution alignment methods have not considered the difference in distribution structures, which results in insufficient alignment across domains. Therefore, a novel graph alignment method is proposed, which aligns both data representations and distribution structural information across the source and target domains. An adversarial network is developed for graph alignment by mapping both source and target data to a feature space where the data are distributed with unified structure criteria. Promising results have been obtained in the experiments on cross-dataset digit and object recognition. Problem of dataset bias also exists in human pose estimation across datasets with different image qualities. Thus, this thesis proposes to synthesize target body parts for cross-domain distribution alignment, to address the problem of cross-quality pose estimation. A translative dictionary is learned to associate the source and target domains, and a cross-quality adaptation model is developed to refine the source pose estimator using the synthesized target body parts. We perform cross-quality experiments on three datasets with different image quality using two state-of-the-art pose estimators, and compare the proposed method with five unsupervised domain adaptation methods. Our experimental results show that the proposed method outperforms not only the source pose estimators, but also other unsupervised domain adaptation methods.