In current research toward the design of more powerful behavior of RTDBS under unpredictable workloads, different research groups focus their work on QoS (Quality of Service) guarantee. their research is often based o...
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In current research toward the design of more powerful behavior of RTDBS under unpredictable workloads, different research groups focus their work on QoS (Quality of Service) guarantee. their research is often based on feedback control real-time scheduling theory. In this paper we propose a technique which allows to execute transactions on time using fresh and precise data while taking into account the global size of the database. We have extended the feedback-based miss ratio control by both using multi-versions data, and proposing a data management policy combining (1) limitation of the versions number and (2) dynamic adjustment of this limit according to a maximum database size parameter.
Correctness of a real-time system depends on its computation as well as its timeliness and its reliability. In recent years, researches have focused on verifying correctness of a real-time system during runtime by mon...
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Correctness of a real-time system depends on its computation as well as its timeliness and its reliability. In recent years, researches have focused on verifying correctness of a real-time system during runtime by monitoring its execution and checking it against its formal specifications. Such verification method is called runtime verification. Most existing runtime verification tools verify computation correctness using qualitative property specifications but do not verify timeliness or reliability correctness. In this paper, we investigate the verification on timeliness and reliability correctness by offering quantitative and probabilistic property specifications and implementing efficient verifiers.
Dynamic voltage scaling (DVS) and dynamic power management (DPM) are widely-used techniques to reduce energy consumption in modern computingsystems. Although combining these techniques can save more energy, there has...
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Dynamic voltage scaling (DVS) and dynamic power management (DPM) are widely-used techniques to reduce energy consumption in modern computingsystems. Although combining these techniques can save more energy, there has not been much work focused on energy-optimal combination of these techniques under variable memory clock frequencies. In this paper, we explore system-wide energy-optimal frequency space for a memory-aware DVS technique based on a stochastic memory access model for systems with frequency-variable memory devices. In addition, we propose a simple but practical DVS method, which can be applied to an actual platform.
A component-based UML profile is built to develop embeddedreal-timesystems. To specify the specific characteristics of embeddedsystems, the model driven architecture (MDA) approach and component-based modeling are ...
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A component-based UML profile is built to develop embeddedreal-timesystems. To specify the specific characteristics of embeddedsystems, the model driven architecture (MDA) approach and component-based modeling are employed. Component-based UML models are designed as Platform Independent Models (PIM) to be translated to platform specific models (PSM) for target-platform implementation, which deal with functional and non-functional properties. Taking specific platform features into regard, specific component models result from transformations mapping a platform-independent component model to either the process and experiment automation real-time language (PEARL) or to function blocks according to IEC 61131-3 or IEC 61499. Both PIM and PSM are collected in a UML profile which can be used as an application framework in developing embeddedreal-timesystems.
the ongoing transition from uniprocessor to multiprocessor computers requires operating system support. there is a large body of specialized operating systems which require porting in order to work on multiprocessors....
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the ongoing transition from uniprocessor to multiprocessor computers requires operating system support. there is a large body of specialized operating systems which require porting in order to work on multiprocessors. In this paper we describe the design and implementation of a multiprocessor port of a cluster operating system kernel. the multiprocessor support is implemented with a giant locking scheme, which allowed us to get an initial working version with only minor changes to the original code. We also discuss performance and implementation experiences.
In this paper, we study the problem of scheduling periodic task sets defined under quality of service (QoS) constraints. In our approach, periodic tasks allow occasional skips of instances. A new algorithm, called RLP...
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In this paper, we study the problem of scheduling periodic task sets defined under quality of service (QoS) constraints. In our approach, periodic tasks allow occasional skips of instances. A new algorithm, called RLP (red tasks as late as possible) based on the skip-over model and the EDL (earliest deadline as late as possible) scheduling strategy, is proposed to enhance the QoS observed for periodic tasks, i.e, the ratio of periodic tasks which complete before their deadline. We prove that our results are never worse than those obtained in previous work. Experimental results also show significant improvement achieved by our algorithm over RTO and BWP.
Large-scale distributed systems, such as ubiquitous computing environments, require a service delivery mechanism in order to keep track of the vast set of services offered and make them available to interested clients...
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Large-scale distributed systems, such as ubiquitous computing environments, require a service delivery mechanism in order to keep track of the vast set of services offered and make them available to interested clients. the amount of services and clients, their context, and loose coupling between them makes service delivery in ubiquitous environments different from other systems. this paper presents a solution to overcome these issues by utilizing the underlying ontology and semantics for service lookup. Access control over context data is also considered by specifying dynamic policies at the system and service level.
In recent years, the use of cache memory has been desired in hard real-timesystems in order to reduce the memory access time. To enable it, accurate analysis of the worst-case execution time considering cache flushes...
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In recent years, the use of cache memory has been desired in hard real-timesystems in order to reduce the memory access time. To enable it, accurate analysis of the worst-case execution time considering cache flushes is necessary since the cache may be flushed by preempting tasks in a multitask environment. this paper proposes a method to find the worst-case timing of cache flushes and demonstrates its effectiveness.
Application-specific instruction set extension to the computational capabilities of a processor provides an efficient mechanism to meet the growing performance and time-to-market demands of embeddedapplications. In t...
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Application-specific instruction set extension to the computational capabilities of a processor provides an efficient mechanism to meet the growing performance and time-to-market demands of embeddedapplications. In this paper, a new methodology for custom instruction set generation is proposed by using profiling technique to analyze CDFG (control and data flow graph) of C program. In the new methodology, we mainly consider major blocks of CDFG of the given application in order to speed up the whole process. It results that for the application, the major blocks fewer, and the process faster. Our approach will significantly reduce the time of the whole process while does not affect the benefit of results. the experimental results demonstrate the improvements over existing techniques.
Context aware middleware infrastructures have traditionally been implemented with a modular approach to allow different components to work cooperatively and supply context synthesis and provision services. In this pap...
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Context aware middleware infrastructures have traditionally been implemented with a modular approach to allow different components to work cooperatively and supply context synthesis and provision services. In this paper, we discuss the important requirements that arise when such a middleware is deployed in a distributed environment and present the design and implementation of context aware middleware for ubiquitous systems (CAMUS) with which the authors have attempted to meet those requirements. Issues related to distributed coordination within the middleware in terms of component discovery and management and multiple context domains are also discussed.
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