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Presented in this thesis is the design and implementation of a fast, compact, and flexible multi-tasking operating system. This system is designed for use in small computers which must deliver real-time performance in extremely constrained environments. The operating system is implemented in the "C" language to allow portability between different computers systems. A number of useful features are provided which support dynamic task management, message passing, a hierarchial file system, device drivers, and a command line interpreter. Modularized construction enables the user to prune unnecessary system features for specific applications. Presently, the system is operational on a personal computer which is also used for system development. This serves as a realistic environment for testing system response to real-time events.

HMS Industrial networks is a company that offers communication solutions for automation systems. There exists an abundance of different industrial network technologies and HMS manufactures gateways that translate and allow communication between the different networks.The multiplicity of network technologies introduces problems when it comes to monitoring the processes in an automation system. It is desirable to be able to access the process data through a single network technology and this is what OPC UA is used for. Briefly, OPC UA can be described as an interface for exchange ofprocess data in automation systems. HMS has noticed a rising trend in the interest for OPC UA and therefore wants to investigate the possibility to use OPC UA on their platform, the Anybus X-Gateway. The goal of this thesis has been to port an OPC UA stack, provided by the OPCfoundation, to the HMS operating system running on an Anybus X-Gateway. The port has been successful and has been verified by unit tests and a test application. Thus, a first step towards a complete OPC UA product has been taken. Further, the thesis presents a theoretical summary about real-time operating systems to explain their function and usage.

Modern applications are increasingly backed by large-scale data centres. Systems software in these data centre environments, however, faces substantial challenges: the lack of uniform resource abstractions makes sharing and resource management inefficient, infrastructure software lacks end-to-end access control mechanisms, and work placement ignores the effects of hardware heterogeneity and workload interference. In this dissertation, I argue that uniform, clean-slate operating system (OS) abstractions designed to support distributed systems can make data centres more efficient and secure. I present a novel distributed operating system for data centres, focusing on two OS components: the abstractions for resource naming, management and protection, and the scheduling of work to compute resources. First, I introduce a reference model for a decentralised, distributed data centre OS, based on pervasive distributed objects and inspired by concepts in classic 1980s distributed OSes. Translucent abstractions free users from having to understand implementation details, but enable introspection for performance optimisation. Fine-grained access control is supported by combining storable, communicable identifier capabilities, and context-dependent, ephemeral handle capabilities. Finally, multi-phase I/O requests implement optimistically concurrent access to objects while supporting diverse application-level consistency policies. Second, I present the DIOS operating system, an implementation of my model as an extension to Linux. The DIOS system call API is centred around distributed objects, globally resolvable names, and translucent references that carry context-sensitive object meta-data. I illustrate how these concepts support distributed applications, and evaluate the performance of DIOS in microbenchmarks and a data-intensive MapReduce application. I find that it offers improved, finegrained isolation of resources, while permitting flexible sharing. Third, I present the Firmament cluster scheduler, which generalises prior work on scheduling via minimum-cost flow optimisation. Firmament can flexibly express many scheduling policies using pluggable cost models; it makes high-quality placement decisions based on fine-grained information about tasks and resources; and it scales the flow-based scheduling approach to very large clusters. In two case studies, I show that Firmament supports policies that reduce colocation interference between tasks and that it successfully exploits flexibility in the workload to improve the energy efficiency of a heterogeneous cluster. Moreover, my evaluation shows that Firmament scales the minimum-cost flow optimisation to clusters of tens of thousands of machines while still making sub-second placement decisions.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005. / Includes bibliographical references (p. 53-55). / Acetone is a secure operating system kernel that uses a shared address space and supports Asbestos labels. Acetone uses Asbestos labels to enable a wide variety of security policies including ones that prevent untrusted applications from being able to disclose private data. All threads run in the same address space, but have different memory access privileges. Acetone uses standard memory protection mechanisms to ensure that all memory accesses are consistent with label rules. The performance results show that these checks have a relatively low cost. / by Clifford A. Frey. / M.Eng.

The default behavior of all commodity operating systems today is to restart the system when a critical error is encountered in the kernel. This terminates all running applications with an attendant loss of "work in progress" that is non-persistent. Our thesis is that an operating system kernel is simply a component of a larger software system, which is logically well isolated from other components, such as applications, and therefore it should be possible to reboot the kernel without terminating everything else running on the same system. In order to prove this thesis, we designed and implemented a new mechanism, called Otherworld, that microreboots the operating system kernel when a critical error is encountered in the kernel, and it does so without clobbering the state of the running applications. After the kernel microreboot, Otherworld attempts to resurrect the applications that were running at the time of failure. It does so by restoring the application memory spaces, open files and other resources. In the default case it then continues executing the processes from the point at which they were interrupted by the failure. Optionally, applications can have user-level recovery procedures registered with the kernel, in which case Otherworld passes control to these procedures after having restored their process state. Recovery procedures might check the integrity of application data and restore resources Otherworld was not able to restore. We implemented Otherworld in Linux, but we believe that the technique can be applied to all commodity operating systems. In an extensive set of experiments on real-world applications (MySQL, Apache/PHP, Joe, vi), we show that Otherworld is capable of successfully microrebooting the kernel and restoring the applications in over 97\% of the cases. In the default case, Otherworld adds negligible overhead to normal execution. In an enhanced mode, Otherworld can provide extra application memory protection with overhead of between 4% and 12%.

The default behavior of all commodity operating systems today is to restart the system when a critical error is encountered in the kernel. This terminates all running applications with an attendant loss of "work in progress" that is non-persistent. Our thesis is that an operating system kernel is simply a component of a larger software system, which is logically well isolated from other components, such as applications, and therefore it should be possible to reboot the kernel without terminating everything else running on the same system. In order to prove this thesis, we designed and implemented a new mechanism, called Otherworld, that microreboots the operating system kernel when a critical error is encountered in the kernel, and it does so without clobbering the state of the running applications. After the kernel microreboot, Otherworld attempts to resurrect the applications that were running at the time of failure. It does so by restoring the application memory spaces, open files and other resources. In the default case it then continues executing the processes from the point at which they were interrupted by the failure. Optionally, applications can have user-level recovery procedures registered with the kernel, in which case Otherworld passes control to these procedures after having restored their process state. Recovery procedures might check the integrity of application data and restore resources Otherworld was not able to restore. We implemented Otherworld in Linux, but we believe that the technique can be applied to all commodity operating systems. In an extensive set of experiments on real-world applications (MySQL, Apache/PHP, Joe, vi), we show that Otherworld is capable of successfully microrebooting the kernel and restoring the applications in over 97\% of the cases. In the default case, Otherworld adds negligible overhead to normal execution. In an enhanced mode, Otherworld can provide extra application memory protection with overhead of between 4% and 12%.

Collections of hardware components are the foundation of computation and consist of interconnections of different types of the same core elements: processors, disks, memory cards, I/O devices, and network links. Designing a system for managing collections of hardware is challenging because modern infrastructures (i) distribute resource control across multiple autonomous sites, (ii) operate diverse sets of hardware, and (iii) support a variety of programming models for developing and executing software services. An operating system is a software layer that manages hardware by coordinating its interaction with software. This thesis defines and evaluates an architecture for a networked operating system that manages collections of hardware in infrastructures spread across networks, such as the Internet. The foundation of a networked operating system determines how software services share a common hardware platform. A fundamental property common to all forms of resource sharing is that software services, by definition, share hardware components and do not use them forever. A lease is a natural construct for restricting the use of a shared resource to a well-defined length of time. Our architecture employs a general neutrality principle, which states that a networked operating system should be policy-neutral, since only users and site administrators, and not operating system developers, know how to manage their software and hardware. Experience building, deploying, and using a prototype has led us to view neutrality as a guiding design principle. Our hypothesis is that an operating system architecture for infrastructure resource management that focuses narrowly on leasing control of hardware provides a foundation for multi-lateral resource negotiation, arbitration, and fault tolerance. In evaluating our hypothesis we make the following contributions:*Introduce a set of design principles for networked operating systems. The principles adapt and extend principles from node operating system design to a networked environment. We evaluate existing systems with respect to these principles, describe how they deviate from them, and explore how these deviations limit the capabilities of higher level software.*Combine the idea of a reconfigurable data center with the Sharp framework for secure resource peering to demonstrate a prototype networked operating system capable of sharing aggregations of resources in infrastructures. *Design, implement, and deploy the architecture using a single programming abstraction---the lease---and show how the lease abstraction embodies the design principles of a networked operating system.*Show that leases are a foundational primitive for addressing arbitration in a networked operating system. Leasing currency defines a configurable tradeoff between proportional-share scheduling and a market economy, and also serves as a basis for implementing other forms of arbitration. *Show how combining the use of leases for long-term resource management with state recovery mechanisms provides robustness to transient faults and failures in a loosely coupled distributed system that coordinates resource allocation.*Evaluate the flexibility and performance of a prototype by managing aggregations of physical and virtual hardware present in modern data centers, and showing that the architecture could scale to manage thousands of machines. *Present case studies of integrating multiple software services including the PlanetLab network testbed, the Plush distributed application manager, and the GridEngine batch scheduler, and leverage the architecture to prototype and evaluate Jaws, a new light-weight batch scheduler that instantiates one or more virtual machines per task. / Dissertation

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 95-101).