real-time logic (RTL) is useful for the verification of a safety assertion SA with respect to the specification SP of a real-time system. Since the satisfiability problem for RTL is undecidable, there were many effort...
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ISBN:
(纸本)0769526764
real-time logic (RTL) is useful for the verification of a safety assertion SA with respect to the specification SP of a real-time system. Since the satisfiability problem for RTL is undecidable, there were many efforts to find proper heuristics for proving that SP -> SA holds. However, none of such heuristics necessarily finds an "optimal implication". After verifying SP -> SA and the system implementing SP is deployed, performance changes as a result of power-saving, faulty components, and cost-saving in the processing platform for the tasks specified in SP affect the computation times of the specified tasks. this leads to a different but related SP, which would violate the original SP -> SA theorem if SA remains the same. It is desirable, therefore, to determine an optimal SP withthe slowest possible computation times for its tasks such that the SA is still guaranteed. this is clearly a fundamental issue in the design and implementation of highly dependable real-time/embeddedsystems. this paper tackles this fundamental issue by describing a new method for relaxing SP and tightening SA such that SP -> SA is still a theorem. Experimental results show that less than 20% overhead of the running time of the algorithm for the verification of SP -> SA is needed to find an optimal theorem.
As the increasing of system performance and computing power, embeddedsystems are more complicated and interactive. therefore, operating system (OS) plays a more important role in embeddedsystems to utilize various h...
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ISBN:
(纸本)0769526764
As the increasing of system performance and computing power, embeddedsystems are more complicated and interactive. therefore, operating system (OS) plays a more important role in embeddedsystems to utilize various hardware and software resources. However, no OS can meet all requirements of various embeddedsystems. Due to the advance of reconfigurable processors, system requirements can be more dynamic. embedded OS has becoming more critical in the development of embeddedsystems and thus there is a strong need of configurable embedded OS to better and faster build up the target system. In this paper, we propose a configurable OS, called COS, based on SOA (Service-Oriented Architecture) for embedded SoC (System on a Chip) systems to build an application specific OS according to the system requirements. COS can be easily configured to better utilize the resources of the target embedded platform and have better support to the embedded application. Moreover, the COS can easily extend new features or functionatities of other OSes and even be adapted to the designs of other OSes. We implement COS on an ARM platform to prove its configurability and also evaluate its overhead. We believe that COS can be configured to meet the various requirements in embedded SoC systems and help to speed up the embedded system development process.
Utilization bounds for Earliest Deadline First(EDF) and Rate Monotonic(RM) scheduling are known and well understood for uniprocessor systems. In this paper, we derive limits on similar bounds for the multiprocessor ca...
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ISBN:
(纸本)0769526764
Utilization bounds for Earliest Deadline First(EDF) and Rate Monotonic(RM) scheduling are known and well understood for uniprocessor systems. In this paper, we derive limits on similar bounds for the multiprocessor case, when the individual processors need not be identical. Tasks are partitioned among the processors and RM scheduling is assumed to be the policy used in individual processors. A minimum limit on the bounds for a 'greedy' class of algorithms is given and proved, since the actual value of the bound depends on the algorithm that allocates the tasks. We also derive the utilization bound of an algorithm which allocates tasks in decreasing order of utilization factors. Knowledge of such bounds allows us to carry out very fast schedulability tests although we are constrained by the fact that the tests are sufficient but not necessary to ensure schedulability.
We present a tool for the design and validation of embeddedreal-timeapplications. the tool integrates two approaches, the use of the synchronous programming language ESTEREL far design and the application of model-c...
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ISBN:
(纸本)0769507344
We present a tool for the design and validation of embeddedreal-timeapplications. the tool integrates two approaches, the use of the synchronous programming language ESTEREL far design and the application of model-checking techniques for validation of real-time properties. Validation is carried out on a global formal model (timed automata) Inking into account the effective implementation of the application on the target hardware architecture as well as its external environment behavior.
Power-aware computing has become an important problem not only in embeddedsystems but also in large-scale data centers in Cloud computing environments. Many recent studies have focused on power-aware virtual machine ...
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ISBN:
(纸本)9781479950799
Power-aware computing has become an important problem not only in embeddedsystems but also in large-scale data centers in Cloud computing environments. Many recent studies have focused on power-aware virtual machine allocation or consolidation. However, few research has been done about implementation of power-aware schedulers in VMM (Virtual Machine Monitor). In this paper, we provide a prototype design for power-aware schedulers in RT-Xen hypervisor. the proposed system is based on compositional real-time scheduling framework which provides a method to abstract each virtual machine into a single component. the proposed prototype includes how to transmit VM real-time requirements into VMM and dynamic frequency control based on those requirements. throughout the experiments, we analyze the proposed prototype and show the performance evaluation.
real-time database system must meet time constraints in addition to the integrity constraints. Concurrency control is one of the main issues in the studies of real-time database systems. Traditional concurrency contro...
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A QoS adaptation to dynamically changing system conditions that takes into consideration the user's constraints on the stability of service provisioning is presented. the goal is to allow the system to make QoS ad...
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ISBN:
(纸本)0769526764
A QoS adaptation to dynamically changing system conditions that takes into consideration the user's constraints on the stability of service provisioning is presented. the goal is to allow the system to make QoS adaptation decisions in response to fluctuations in task traffic flow, under the control of the user We pay special attention to the case where monitoring the stability period and resource load variation of Service Level Agreements for different types of services is used to dynamically adapt future stability periods, according to a feedback control scheme. System's adaptation behaviour can be configured according to a desired confidence level on future resource usage. the viability of the proposed approach is validated by preliminary experiments.
Compositional real-time scheduling frameworks provide ways for building large and complex real-timeembeddedsystems from independent sub-systems. this paper introduces a novel scheme for scheduling a component of Mix...
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ISBN:
(纸本)9781479950799
Compositional real-time scheduling frameworks provide ways for building large and complex real-timeembeddedsystems from independent sub-systems. this paper introduces a novel scheme for scheduling a component of Mixed-Criticality (MC) sporadic tasks on uniprocessor system. It characterizes the mixed criticality resource allocations, and the interface model for abstracting the real-time requirements of such a component. the demand bound function and supply bound function for the low and high criticality modes are derived to determine the schedulability of a component in both modes. the execution times of jobs are monitored in this approach. If it is detected that the behavior of system is inconsistent with low criticality level, then tasks of low criticalities are discarded and the priorities of high criticality tasks are re-ordered in high criticality mode to guarantee the schedulabilty of high criticality tasks. We propose a new algorithm, which schedules a component of mixed criticality jobs in low mode through MC Rate Monotonic (MC-RM) algorithm by applying period transformation, and guarantees the schedulabilty by using MC Earliest Deadline First (MC-EDF) algorithm in high mode.
the usage of caches in multi-and many-core systems for timing critical applications is a challenging issue. time-predictability shaped up as the essential characteristic of a cache when talking about the suitability f...
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ISBN:
(纸本)9780769550220
the usage of caches in multi-and many-core systems for timing critical applications is a challenging issue. time-predictability shaped up as the essential characteristic of a cache when talking about the suitability for hard real-timesystems. Common cache coherence mechanisms corrupt the timing analysability of a cache memory because of unpredictable interferences between the caches. thus, these mechanisms are unsuitable for hard real-timesystems. In this work, we briefly describe the ODC2 together with an extension which increases the cache hit rate. We evaluated the performance of the extended ODC2 by comparing it to analysable uncached accesses to shared data and to the well-known but unpredictable MESI and MOESI coherence techniques.
the importance of accounting for interrupts in multiprocessor real-time schedulability analsysis is discussed: three interrupt accounting methods, two of which are newly described here, are analyzed and compared.
ISBN:
(纸本)9780769537870
the importance of accounting for interrupts in multiprocessor real-time schedulability analsysis is discussed: three interrupt accounting methods, two of which are newly described here, are analyzed and compared.
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