On Intelligent Mitigation of Process Starvation In Multilevel Feedback Queue Scheduling

CPU time-share process schedulers for computer operating systems have existed since Corbato published his paper on the Compatible Time Sharing System in 1962 [8]. With this new type of scheduler came the need to effectively divide CPU time between N processes, where N could be 2 or more processes. Modern time-sharing process schedulers which have been developed in the decades since have been designed to favor shorter, interactive processes over long-running processes, especially when incoming demand for CPU time exceeds supply and process starvation is inevitable. These schedulers, including Linux CFS, FreeBSD Ule, and the Solaris Fair Share Scheduler, are all effective at favoring interactive processes under starvation conditions. Sometimes it’s not desirable that long-running processes be sacrificed altogether, but none of these schedulers have safeguards under starvation conditions. This thesis revisits and extends the research conducted in [13], in which it was demonstrated that starvation of long-running processes could be safely and effectively mitigated without adversely affecting the performance of shorter, interactive processes. The questions this thesis will answer are: Can MLFQ-NS, proposed in [13], be compared to other modern process schedulers? Can MLFQ-NS be improved? To answer the first question, a scheduler must be found which is similar enough to MFLQ for a direct comparison. This will require a survey of current schedulers. To answer the second question, the research conducted in [13] must be duplicated MLFQ-NS to ascertain the following: How much diverted time is actually used? Why does MLFQ-NS become ineffective past a certain system-load threshold, i.e. stop real- locating time to long-runnning processes? In this research, the original work was duplicated in simulations to validate previous re- sults, and determine why MLFQ-NS became ineffective after incoming CPU time demand exceeds a threshold. Research was conducted in order to determine if starvation mitigation in MLFQ-NS could be compared to other process schedulers used in production, with the conclusion that recent emphasis on priority scheduling and heurstic interactivity determination makes such a comparison impossible. Research then continued with simulations in which MLFQ-NS was given different run- time arguments than original simulations. Investigations into those results led to an algorithmic modification to MLFQ-NS called MLFQ-IM and analysis of simulations of MLFQ-IM. Conclu- sions about the effectiveness of MLFQ-IM will be explored. Finally, ideas for future research are offered

Implementasi Algoritma Penjadwalan Multilevel Feedback Queue pada Aplikasi Berbasis Flutter

Application development has experienced a shift towards a cross-platform approach, where developers can write code once for multiple platforms. Flutter, as a fast-growing cross-platform framework with a wide community is one of the most popular cross-platform frameworks today. However, along with that, there is an increase in application complexity which makes the concept of multitasking very important. This article proposes the implementation of the Multilevel Feedback Queue (MLQ) scheduling algorithm in Flutter applications, which can help manage tasks and improve application efficiency. This research aims to examine the changes in application efficiency after the implementation of MLQ, as well as examine whether the changes remain relevant on different operating systems, namely Windows and Android. The implemented MLQ algorithm is an algorithm with adjustments to the calculation of time quantum and integration with the Shortest Job First (SJF) algorithm based on previous research. Tests were conducted using the Flutter benchmarking feature to measure the application frame rate before and after MLQ implementation on Windows and Android. The results of this study found that the implementation of MLQ increased application efficiency by 269% on the Windows operating system and 155% on the Android operating system

Deadline-Driven Auctions for NPC Host Allocation on P2P MMOGs.

We present the design, implementation and evaluation of Deadline-Driven Auctions (DDAs), a novel task-mapping infrastructure for heterogeneous distributed environments. DDA is primarily designed for hosting Non-Player Characters (NPCs) in P2P Massively Multiplayer Online Games (MMOGs). Experimental and analytical results demonstrate that DDA provides four significant advantages. It is self-organising: the infrastructure is automatically managed. It efficiently allocates computing resources for large numbers (1000s) of real-time NPC tasks. It supports gaming interactivity by minimising communication latency between NPC hosts. Finally, it supports flexible matchmaking policies, and a friendly incentive policy establishes a cooperative economic model to motivate participants to contribute resources

Low-latency Networking: Where Latency Lurks and How to Tame It

While the current generation of mobile and fixed communication networks has been standardized for mobile broadband services, the next generation is driven by the vision of the Internet of Things and mission critical communication services requiring latency in the order of milliseconds or sub-milliseconds. However, these new stringent requirements have a large technical impact on the design of all layers of the communication protocol stack. The cross layer interactions are complex due to the multiple design principles and technologies that contribute to the layers' design and fundamental performance limitations. We will be able to develop low-latency networks only if we address the problem of these complex interactions from the new point of view of sub-milliseconds latency. In this article, we propose a holistic analysis and classification of the main design principles and enabling technologies that will make it possible to deploy low-latency wireless communication networks. We argue that these design principles and enabling technologies must be carefully orchestrated to meet the stringent requirements and to manage the inherent trade-offs between low latency and traditional performance metrics. We also review currently ongoing standardization activities in prominent standards associations, and discuss open problems for future research

Co-design of Security Aware Power System Distribution Architecture as Cyber Physical System

The modern smart grid would involve deep integration between measurement nodes, communication systems, artificial intelligence, power electronics and distributed resources. On one hand, this type of integration can dramatically improve the grid performance and efficiency, but on the other, it can also introduce new types of vulnerabilities to the grid. To obtain the best performance, while minimizing the risk of vulnerabilities, the physical power system must be designed as a security aware system. In this dissertation, an interoperability and communication framework for microgrid control and Cyber Physical system enhancements is designed and implemented taking into account cyber and physical security aspects. The proposed data-centric interoperability layer provides a common data bus and a resilient control network for seamless integration of distributed energy resources. In addition, a synchronized measurement network and advanced metering infrastructure were developed to provide real-time monitoring for active distribution networks. A hybrid hardware/software testbed environment was developed to represent the smart grid as a cyber-physical system through hardware and software in the loop simulation methods. In addition it provides a flexible interface for remote integration and experimentation of attack scenarios. The work in this dissertation utilizes communication technologies to enhance the performance of the DC microgrids and distribution networks by extending the application of the GPS synchronization to the DC Networks. GPS synchronization allows the operation of distributed DC-DC converters as an interleaved converters system. Along with the GPS synchronization, carrier extraction synchronization technique was developed to improve the system’s security and reliability in the case of GPS signal spoofing or jamming. To improve the integration of the microgrid with the utility system, new synchronization and islanding detection algorithms were developed. The developed algorithms overcome the problem of SCADA and PMU based islanding detection methods such as communication failure and frequency stability. In addition, a real-time energy management system with online optimization was developed to manage the energy resources within the microgrid. The security and privacy were also addressed in both the cyber and physical levels. For the physical design, two techniques were developed to address the physical privacy issues by changing the current and electromagnetic signature. For the cyber level, a security mechanism for IEC 61850 GOOSE messages was developed to address the security shortcomings in the standard

Solving key design issues for massively multiplayer online games on peer-to-peer architectures

Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and scale on the Internet and are predominantly implemented by Client/Server architectures. While such a classical approach to distributed system design offers many benefits, it suffers from significant technical and commercial drawbacks, primarily reliability and scalability costs. This realisation has sparked recent research interest in adapting MMOGs to Peer-to-Peer (P2P) architectures. This thesis identifies six key design issues to be addressed by P2P MMOGs, namely interest management, event dissemination, task sharing, state persistency, cheating mitigation, and incentive mechanisms. Design alternatives for each issue are systematically compared, and their interrelationships discussed. How well representative P2P MMOG architectures fulfil the design criteria is also evaluated. It is argued that although P2P MMOG architectures are developing rapidly, their support for task sharing and incentive mechanisms still need to be improved. The design of a novel framework for P2P MMOGs, Mediator, is presented. It employs a self-organising super-peer network over a P2P overlay infrastructure, and addresses the six design issues in an integrated system. The Mediator framework is extensible, as it supports flexible policy plug-ins and can accommodate the introduction of new superpeer roles. Key components of this framework have been implemented and evaluated with a simulated P2P MMOG. As the Mediator framework relies on super-peers for computational and administrative tasks, membership management is crucial, e.g. to allow the system to recover from super-peer failures. A new technology for this, namely Membership-Aware Multicast with Bushiness Optimisation (MAMBO), has been designed, implemented and evaluated. It reuses the communication structure of a tree-based application-level multicast to track group membership efficiently. Evaluation of a demonstration application shows i that MAMBO is able to quickly detect and handle peers joining and leaving. Compared to a conventional supervision architecture, MAMBO is more scalable, and yet incurs less communication overheads. Besides MMOGs, MAMBO is suitable for other P2P applications, such as collaborative computing and multimedia streaming. This thesis also presents the design, implementation and evaluation of a novel task mapping infrastructure for heterogeneous P2P environments, Deadline-Driven Auctions (DDA). DDA is primarily designed to support NPC host allocation in P2P MMOGs, and specifically in the Mediator framework. However, it can also support the sharing of computational and interactive tasks with various deadlines in general P2P applications. Experimental and analytical results demonstrate that DDA efficiently allocates computing resources for large numbers of real-time NPC tasks in a simulated P2P MMOG with approximately 1000 players. Furthermore, DDA supports gaming interactivity by keeping the communication latency among NPC hosts and ordinary players low. It also supports flexible matchmaking policies, and can motivate application participants to contribute resources to the system

Incident Traffic Management Respone

The North Carolina State Highway Patrol (NCSHP) and the North Carolina Department of Transportation (NCDOT) are often called upon to assist in traffic incidents. Yet little systematic research has examined the extent to which these two agencies collaborate. This gap in understanding is problematic, as a lack of collaboration may result in significant delays in the clearing of traffic incidents. The purpose of this correlational study was to investigate circumstances when the two agencies collaborated in clearing major traffic incidents, and the efficiency of the clearance of the incidents, through the measurement of normal traffic flow. The theory of the convergence of resources from divergent organizations framed the study. The research questions addressed the extent of collaboration between the NCSHP and the NCDOT, the conditions under which this collaboration took place, and the efficiency of the clearance of these incidents. Data were obtained from the NCSHP and the NCDOT on characteristics of 1,580 traffic incidents that occurred on the North Carolina portion of Interstate 95 during the year 2014. The data were analyzed using chi-square tests, analyses of variance, and Z-tests for proportions. Collaboration between the two agencies occurred in 7.2% of all of the incidents and in 21.6% of incidents of major severity (p \u3c .001), which indicated a low level of interagency collaboration. The mean clearance time for incidents in which collaboration took place was 115.92 minutes compared to a national goal of 90 minutes. It is hoped that these results can contribute to policy dialogue relevant to the state\u27s Strategic Plan, leading to safer highways and less financial loss due to congestion caused by traffic incidents