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23rd IEEE Real-Time Systems Symposium, 2002. RTSS 2002.

3-5 Dec. 2002

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Displaying Results 1 - 25 of 32
  • Proceedings Real-Time Systems Symposium

    Publication Year: 2002
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  • State-dependent deadline scheduling

    Publication Year: 2002, Page(s):3 - 14
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (447 KB) | HTML iconHTML

    This paper presents a new workload model, called the state-dependent deadline model, for applications whose high-level timing requirements may change with time. The problem is how to choose target deadlines for jobs from their time-varying deadlines so that the system can meet its requirements with a high probability. In the clairvoyant case, the deadline of every job is given by a known function ... View full abstract»

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  • Scheduling aperiodic requests under the rate-based execution model

    Publication Year: 2002, Page(s):15 - 25
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (377 KB) | HTML iconHTML

    Aperiodic requests with unknown execution times and unknown arrival patterns are dynamically mapped to rate-based execution (RBE) tasks with variable rates and scheduled such that the real-time tasks are guaranteed to meet their deadlines. The aperiodic requests dynamically share the available processor capacity without reserving a fixed processor capacity for any one aperiodic request (or class o... View full abstract»

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  • A model of hierarchical real-time virtual resources

    Publication Year: 2002, Page(s):26 - 35
    Cited by:  Papers (66)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (335 KB) | HTML iconHTML

    A real-time virtual resource is an abstraction for resource sharing where application task groups must meet timing constraints and knowledge of all the timing requirements may not be available for a global schedulability analysis, such as is the case in the open system environment. In a 2001 paper, we introduced the notion of a real-time virtual resource which operates at a fraction of the rate of... View full abstract»

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  • An implicit prioritized access protocol for wireless sensor networks

    Publication Year: 2002, Page(s):39 - 48
    Cited by:  Papers (112)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1249 KB) | HTML iconHTML

    Recent advances in wireless technology have brought us closer to the vision of pervasive computing where sensors/actuators can be connected through a wireless network. Due to cost constraints and the dynamic nature of sensor networks, it is undesirable to assume the existence of base stations connected by a wired backbone. In this paper, we present a network architecture suitable for sensor networ... View full abstract»

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  • End-to-end fairness analysis of fair queuing networks

    Publication Year: 2002, Page(s):49 - 58
    Cited by:  Papers (1)  |  Patents (6)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (344 KB) | HTML iconHTML

    In this paper, we present the first end-to-end fairness analysis of a network of fair servers. We argue that it is difficult to extend existing single-node fairness analysis to an end-to-end analysis of a network where each node may employ a different fair scheduling algorithm. We then present a two-step approach for end-to-end fairness analysis of heterogeneous networks. First, we define a class ... View full abstract»

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  • Scheduling periodic hard real-time tasks with arbitrary deadlines on multiprocessors

    Publication Year: 2002, Page(s):59 - 68
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (392 KB) | HTML iconHTML

    Pfair scheduling has usually been applied in the context of scheduling periodic tasks with coinciding periods and deadlines. This paper addresses the problem of scheduling hard real-time tasks characterized by arbitrary deadlines in a pfair manner on multiprocessor systems. We prove fundamental properties of the weight functions of such tasks and show that when such tasks are scheduled in a pfair ... View full abstract»

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  • Analysis of a reservation-based feedback scheduler

    Publication Year: 2002, Page(s):71 - 80
    Cited by:  Papers (73)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (426 KB) | HTML iconHTML

    When executing soft real-time tasks in a shared processor, it is important to properly allocate the computational resources such that the quality of service requirements of each task are satisfied. In this paper we propose Adaptive Reservations, based on applying a feedback scheme to a reservation based scheduler After providing a precise mathematical model of the scheduler, we describe how this m... View full abstract»

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  • Queueing model based network server performance control

    Publication Year: 2002, Page(s):81 - 90
    Cited by:  Papers (49)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (544 KB) | HTML iconHTML

    Controlling the timing performance of a network server is a challenging problem. This paper presents a Queueing Model Based Feedback Control approach to keep the timing performance of a network server close to the service level specification. We show that in an instrumented Apache server, combining feedback control with a queueing model leads to better tracking of QoS specifications than with feed... View full abstract»

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  • Improving quality-of-control using flexible timing constraints: metric and scheduling

    Publication Year: 2002, Page(s):91 - 100
    Cited by:  Papers (32)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (682 KB) | HTML iconHTML

    Closed-loop control systems are dynamic systems subject to perturbations. One of the main concerns of the control is to design controllers to correct or limit the deviation that transient perturbations cause in the controlled system response. The smaller and shorter the deviation, the better the achieved performance. However, such controllers have been traditionally implemented using fixed timing ... View full abstract»

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  • Compiling for fine-grain concurrency: planning and performing software thread integration

    Publication Year: 2002, Page(s):103 - 113
    Cited by:  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (381 KB) | HTML iconHTML

    Embedded systems require control of many concurrent real-time activities, leading to system designs which feature multiple hardware peripherals with each providing a specific, dedicated service. These peripherals increase system size, cost, weight, power and design time. Software thread integration (STI) provides low-cost thread concurrency on general-purpose processors by automatically interleavi... View full abstract»

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  • Low-complexity algorithms for static cache locking in multitasking hard real-time systems

    Publication Year: 2002, Page(s):114 - 123
    Cited by:  Papers (70)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (376 KB) | HTML iconHTML

    Cache memories have been extensively used to bridge the gap between high speed processors and relatively slow main memories. However, they are a source of predictability problems because of their dynamic and adaptive behavior and thus need special attention to be used in hard-real time systems. A lot of progress has been achieved in the last ten years to statically predict the worst-case behavior ... View full abstract»

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  • Cost and benefit of separate address spaces in real-time operating systems

    Publication Year: 2002, Page(s):124 - 133
    Cited by:  Papers (10)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (318 KB) | HTML iconHTML

    The combination of a real-time executive and an off-the-shelf time-sharing operating system has the potential of providing both predictability and the comfort of a large application base. To isolate the real-time section from a significant class of faults in the (ever-growing) time-sharing operating system, address spaces can be used to encapsulate the time-sharing subsystem. However, in practice,... View full abstract»

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  • Soft real-time scheduling on simultaneous multithreaded processors

    Publication Year: 2002, Page(s):134 - 145
    Cited by:  Papers (30)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1720 KB) | HTML iconHTML

    Simultaneous multithreading (SMT) improves processor throughput by processing instructions from multiple threads each cycle. This is the first work to explore soft real-time scheduling on an SMT processor. Scheduling with SMT requires two decisions: (1) which threads to run simultaneously (the co-schedule), and (2) how to share processor resources among co-scheduled threads. We explore algorithms ... View full abstract»

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  • Locking in pfair-scheduled multiprocessor systems

    Publication Year: 2002, Page(s):149 - 158
    Cited by:  Papers (14)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (437 KB) | HTML iconHTML

    We consider two classes of locking synchronization protocols for pfair-scheduled multiprocessor systems: short critical-section protocols and long critical-section protocols. For the former class, we demonstrate that efficient synchronization can be achieved by ensuring that all locks have been released before tasks are preempted. For the latter class, we propose the use of statically-weighted res... View full abstract»

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  • Approximate schedulability analysis

    Publication Year: 2002, Page(s):159 - 168
    Cited by:  Papers (20)  |  Patents (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (404 KB) | HTML iconHTML

    The schedulability analysis problem for many realistic task models is intractable. Therefore, known algorithms either have exponential complexity or at best can be solved in pseudo-polynomial time, thereby restricting application of the concerned models to a large extent. We introduce the notion of "approximate schedulability analysis" and show that if a small amount of "error" (which is specified... View full abstract»

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  • The space of rate monotonic schedulability

    Publication Year: 2002, Page(s):169 - 178
    Cited by:  Papers (16)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (441 KB) | HTML iconHTML

    Feasibility analysis of fixed priority systems has been widely studied in the real-time literature and several acceptance tests have been proposed to guarantee a set of periodic tasks. They can be divided into two main classes: polynomial time tests and exact tests. Polynomial time tests are used for an online guarantee of dynamic systems, where tasks can be activated at runtime. These tests intro... View full abstract»

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  • Formal verification of overhead accounting in an avionics RTOS

    Publication Year: 2002, Page(s):181 - 190
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (329 KB) | HTML iconHTML

    This paper describes our work modeling key portions of the safety-critical software infrastructure in an integrated modular avionics (IMA) platform in an effort to analytically establish correctness of important aspects of its design. In particular, we use model checking to verify timing properties of the Deos/spl trade/ real-time operating system in the presence of various advanced scheduling fea... View full abstract»

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  • The monitoring of timing constraints on time intervals

    Publication Year: 2002, Page(s):191 - 200
    Cited by:  Papers (12)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (398 KB) | HTML iconHTML

    Efficient algorithms have been developed by a number of authors to detect constraint violation or satisfaction of timed events. In extant work, the time of every event occurrence is assumed to be known exactly. However there are practical situations where we are not sure about the exact time of occurrence of an event but we may be able to capture the uncertainty by a time interval. In this paper w... View full abstract»

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  • Embedded system design framework for minimizing code size and guaranteeing real-time requirements

    Publication Year: 2002, Page(s):201 - 211
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (343 KB) | HTML iconHTML

    In addition to real-time requirements, program code size is a critical design factor for real-time embedded systems. To take advantage of the code size vs. execution time trade off provided by reduced bit-width instructions, we propose a design framework that transforms system constraints into task parameters guaranteeing a set of requirements. The goal of our design framework is to derive the tem... View full abstract»

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  • Optimal partitioning for quantized EDF scheduling

    Publication Year: 2002, Page(s):212 - 222
    Cited by:  Papers (2)  |  Patents (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1360 KB) | HTML iconHTML

    The quantized earliest deadline first (Q-EDF) scheduling policy assumes a limited number of priority levels available to express task (or packet) deadlines. This situation arises in computer and communication systems in which priority levels must be expressed using a limited number of bits. The range of possible deadlines is partitioned into bins, and a task whose deadline lies within the range of... View full abstract»

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  • A fast resource synthesis technique for energy-efficient real-time systems

    Publication Year: 2002, Page(s):225 - 234
    Cited by:  Papers (7)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1775 KB) | HTML iconHTML

    We consider a resource synthesis technique for real-time systems where the energy budget is limited and the performance of the system depends on how resources and energy are used. We consider two performance models for a task: (1) a task has variable execution time and performance of a task depends on the amount of execution time received, and (2) the execution time of a task is constant and the p... View full abstract»

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  • Processor voltage scheduling for real-time tasks with non-preemptible sections

    Publication Year: 2002, Page(s):235 - 245
    Cited by:  Papers (41)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (896 KB) | HTML iconHTML

    As mobile computing becomes more popular, there is increasing interest in techniques that can minimize energy consumption and prolong the battery life of mobile devices. Processor voltage scheduling is an effective way of reducing energy dissipation by reducing processor speed. We study voltage scheduling for real-time periodic tasks with non-preemptible sections. Three schemes are proposed to add... View full abstract»

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  • Maximizing the system value while satisfying time and energy constraints

    Publication Year: 2002, Page(s):246 - 255
    Cited by:  Papers (37)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (357 KB) | HTML iconHTML

    Typical real-time scheduling theory has addressed deadline and energy constraints as well as deadline and reward constraints simultaneously in the past. However we believe that embedded devices with varying applications typically have three constraints that need to be addressed: energy, deadline, and reward. These constraints play important roles in the next generation of embedded devices, since t... View full abstract»

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  • Energy-efficient duplex and TMR real-time systems

    Publication Year: 2002, Page(s):256 - 266
    Cited by:  Papers (15)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (408 KB) | HTML iconHTML

    Duplex and triple modular redundancy (TMR) systems are used when a high-level of reliability is desired. Real-time systems for autonomous critical missions need such degrees of reliability, but energy consumption becomes a dominant concern when these systems are built from high-performance processors that consume a large budget of electrical power for operation and cooling. Examples where energy c... View full abstract»

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