This paper describes the structure of a tool to predict safe and tight upper bounds of the worst-case execution time (WCET) of tasks running on embedded processors and the use of a WCET tool in an industrial context. We describe common obstacles in the initial use of a WCET tool and consider the integration with scheduling analysis and model-based design tools.
{"title":"Worst-Case Execution Time - A Tool Provider's Perspective","authors":"C. Ferdinand, Reinhold Heckmann","doi":"10.1109/ISORC.2008.16","DOIUrl":"https://doi.org/10.1109/ISORC.2008.16","url":null,"abstract":"This paper describes the structure of a tool to predict safe and tight upper bounds of the worst-case execution time (WCET) of tasks running on embedded processors and the use of a WCET tool in an industrial context. We describe common obstacles in the initial use of a WCET tool and consider the integration with scheduling analysis and model-based design tools.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130827914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The performance of autonomous vehicles could be drastically improved if ad-hoc networking and suitable real-time coordination is employed to optimize and improve the joint behavior of multiple autonomous units. However, due to ad-hoc connections and the real-time interaction the correctness and safety of such coordinated autonomous units is very hard to ensure. In this paper we present how service- oriented real-time coordination can be employed to achieve this goal. Based on the proper real-time coordination between two or more vehicles captured by a service contract, we focus on structural changes and the instantiation and termination of service contracts which is a crucial prerequisite for a safe system operation. We present how the structural changes and the service contract creation/deletion can be modeled by a well-defined UML subset consisting of class and object diagrams with collaborations as well as well-defined behavioral rules can be verified taking the dynamic structural changes due to the ad-hoc networking as well as the real-time coordination into account. The new verification technique is outlined and the application of the technique for an application example is presented.
{"title":"On Safe Service-Oriented Real-Time Coordination for Autonomous Vehicles","authors":"Basil Becker, H. Giese","doi":"10.1109/ISORC.2008.13","DOIUrl":"https://doi.org/10.1109/ISORC.2008.13","url":null,"abstract":"The performance of autonomous vehicles could be drastically improved if ad-hoc networking and suitable real-time coordination is employed to optimize and improve the joint behavior of multiple autonomous units. However, due to ad-hoc connections and the real-time interaction the correctness and safety of such coordinated autonomous units is very hard to ensure. In this paper we present how service- oriented real-time coordination can be employed to achieve this goal. Based on the proper real-time coordination between two or more vehicles captured by a service contract, we focus on structural changes and the instantiation and termination of service contracts which is a crucial prerequisite for a safe system operation. We present how the structural changes and the service contract creation/deletion can be modeled by a well-defined UML subset consisting of class and object diagrams with collaborations as well as well-defined behavioral rules can be verified taking the dynamic structural changes due to the ad-hoc networking as well as the real-time coordination into account. The new verification technique is outlined and the application of the technique for an application example is presented.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132424559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The real-time computing community uses the terms "predictability" and "determinism" - usually referring to timeliness - without defining them, or incorrectly as synonyms. That results in confusion, errors, and neglect of important mainstream real-time systems, especially dynamic distributed ones.
{"title":"Wrong Assumptions and Neglected Areas in Real-Time Systems","authors":"E. Jensen","doi":"10.1109/ISORC.2008.85","DOIUrl":"https://doi.org/10.1109/ISORC.2008.85","url":null,"abstract":"The real-time computing community uses the terms \"predictability\" and \"determinism\" - usually referring to timeliness - without defining them, or incorrectly as synonyms. That results in confusion, errors, and neglect of important mainstream real-time systems, especially dynamic distributed ones.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124726026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic cast operation allows flexibility in the design and use of data management facilities in object- oriented programs. Dynamic cast has an important role in the implementation of the data management services (DMS) of the mission data system project (MDS), the jet propulsion laboratory's experimental work for providing a state-based and goal-oriented unified architecture for testing and development of mission software. DMS is responsible for the storage and transport of control and scientific data in a remote autonomous spacecraft. Like similar operators in other languages, the C++ dynamic cast operator does not provide the timing guarantees needed for hard real-time embedded systems. In a recent study, Gibbs and Stroustrup (G&S) devised a dynamic cast implementation strategy that guarantees fast constant-time performance. This paper presents the definition and application of a co-simulation framework to formally verify and evaluate the G&S fast dynamic casting scheme and its applicability in the mission data system DMS application. We describe the systematic process of model-based simulation and analysis that has lead to performance improvement of the G&S algorithm's heuristics by about a factor of 2.
{"title":"C++ Dynamic Cast in Autonomous Space Systems","authors":"D. Dechev, R. Mahapatra, B. Stroustrup, D. Wagner","doi":"10.1109/ISORC.2008.20","DOIUrl":"https://doi.org/10.1109/ISORC.2008.20","url":null,"abstract":"The dynamic cast operation allows flexibility in the design and use of data management facilities in object- oriented programs. Dynamic cast has an important role in the implementation of the data management services (DMS) of the mission data system project (MDS), the jet propulsion laboratory's experimental work for providing a state-based and goal-oriented unified architecture for testing and development of mission software. DMS is responsible for the storage and transport of control and scientific data in a remote autonomous spacecraft. Like similar operators in other languages, the C++ dynamic cast operator does not provide the timing guarantees needed for hard real-time embedded systems. In a recent study, Gibbs and Stroustrup (G&S) devised a dynamic cast implementation strategy that guarantees fast constant-time performance. This paper presents the definition and application of a co-simulation framework to formally verify and evaluate the G&S fast dynamic casting scheme and its applicability in the mission data system DMS application. We describe the systematic process of model-based simulation and analysis that has lead to performance improvement of the G&S algorithm's heuristics by about a factor of 2.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129128755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Po-Chun Huang, Yuan-Hao Chang, Tei-Wei Kuo, Jen-Wei Hsieh, M. Lin
Performance and reliability are two major design concerns of flash-memory storage systems, especially for low-cost products. Although various excellent flash- memory management schemes are proposed, there is little work done on how to evaluate the designs or implementations of flash-memory storage systems. Many of the existing evaluation workloads for flash-memory storage systems still rely on those based on hard disks. This work aims at the needs of behavior analysis of flash-memory storage systems and their evaluations. In particular, a set of evaluation metrics and their corresponding access patterns are proposed. The behaviors of flash memory are also analyzed in terms of performance and reliability issues.
{"title":"The Behavior Analysis of Flash-Memory Storage Systems","authors":"Po-Chun Huang, Yuan-Hao Chang, Tei-Wei Kuo, Jen-Wei Hsieh, M. Lin","doi":"10.1109/ISORC.2008.33","DOIUrl":"https://doi.org/10.1109/ISORC.2008.33","url":null,"abstract":"Performance and reliability are two major design concerns of flash-memory storage systems, especially for low-cost products. Although various excellent flash- memory management schemes are proposed, there is little work done on how to evaluate the designs or implementations of flash-memory storage systems. Many of the existing evaluation workloads for flash-memory storage systems still rely on those based on hard disks. This work aims at the needs of behavior analysis of flash-memory storage systems and their evaluations. In particular, a set of evaluation metrics and their corresponding access patterns are proposed. The behaviors of flash memory are also analyzed in terms of performance and reliability issues.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129143036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Predictable deployment and configuration (D&C) of components in response to dynamic environmental changes or system mode changes is essential for ensuring open distributed real-time and embedded (DRE) system real-time QoS. This paper provides three contributions to research on the predictability of D&C for component-based open DRE systems. First, we describe how the dependency relationships among different components and their criticality levels can cause deployment order inversion of tasks, which impedes deployment predictability. Second, we describe how to minimize D&C latency of mission-critical tasks with a multi-graph dependency tracing and graph recomposition algorithm called CaDAnCE. Third, we empirically evaluate the effectiveness of CaDAnCE on a representative open DRE system case study based on NASA Earth Science Enterprise's Magnetospheric Multi-Scale (MMS) mission system. Our results show that CaDAnCE avoids deployment order inversion while incurring negligible (<1%) performance overhead, thereby significantly improving D&C predictability.
{"title":"CaDAnCE: A Criticality-Aware Deployment and Configuration Engine","authors":"Gan Deng, D. Schmidt, A. Gokhale","doi":"10.1109/ISORC.2008.58","DOIUrl":"https://doi.org/10.1109/ISORC.2008.58","url":null,"abstract":"Predictable deployment and configuration (D&C) of components in response to dynamic environmental changes or system mode changes is essential for ensuring open distributed real-time and embedded (DRE) system real-time QoS. This paper provides three contributions to research on the predictability of D&C for component-based open DRE systems. First, we describe how the dependency relationships among different components and their criticality levels can cause deployment order inversion of tasks, which impedes deployment predictability. Second, we describe how to minimize D&C latency of mission-critical tasks with a multi-graph dependency tracing and graph recomposition algorithm called CaDAnCE. Third, we empirically evaluate the effectiveness of CaDAnCE on a representative open DRE system case study based on NASA Earth Science Enterprise's Magnetospheric Multi-Scale (MMS) mission system. Our results show that CaDAnCE avoids deployment order inversion while incurring negligible (<1%) performance overhead, thereby significantly improving D&C predictability.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129628069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As ITS technology evolves, very large volume of traffic data can be obtained in real-time. Traffic data are continuously produced and they can be considered as a kind of stream data. Currently, such traffic data are not maintained permanently because of the storage limitations of operational systems. Therefore, it was impossible to compare temporal historical patterns over long time periods. In this paper, we propose a traffic data management scheme, which can handle historical data as well as current data. The proposed scheme is based on the GALIS architecture, which is a cluster-based distributed computing system architecture that consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. Some experimental results showing performance factors are also explained.
{"title":"Distributed Real-Time Traffic Data Management","authors":"Joonwook Lee, Jaeil Hwang, Dong-Hoon Shin, Yunmook Nah, Hae-Young Bae, Doohyun Kim","doi":"10.1109/ISORC.2008.35","DOIUrl":"https://doi.org/10.1109/ISORC.2008.35","url":null,"abstract":"As ITS technology evolves, very large volume of traffic data can be obtained in real-time. Traffic data are continuously produced and they can be considered as a kind of stream data. Currently, such traffic data are not maintained permanently because of the storage limitations of operational systems. Therefore, it was impossible to compare temporal historical patterns over long time periods. In this paper, we propose a traffic data management scheme, which can handle historical data as well as current data. The proposed scheme is based on the GALIS architecture, which is a cluster-based distributed computing system architecture that consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. Some experimental results showing performance factors are also explained.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121281187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Some emerging networked embedded real-time applications have relatively long reaction time magnitudes-e.g., milliseconds to minutes. These longer execution time magnitudes allow opportunities for more computationally expensive scheduling algorithms than what is traditionally considered for device-level real-time control sub-systems. In this paper, we review recent research conducted on collaborative scheduling algorithms in such systems that are subject to dynamic behavior such as transient and sustained resource overloads, arbitrary activity arrivals, and arbitrary node failures and message loss. We show that collaborative scheduling algorithms have an advantage over non-collaborative scheduling algorithms.
{"title":"On Collaborative Scheduling of Distributable Real-Time Threads in Dynamic, Networked Embedded Systems","authors":"S. Fahmy, B. Ravindran, E. Jensen","doi":"10.1109/ISORC.2008.11","DOIUrl":"https://doi.org/10.1109/ISORC.2008.11","url":null,"abstract":"Some emerging networked embedded real-time applications have relatively long reaction time magnitudes-e.g., milliseconds to minutes. These longer execution time magnitudes allow opportunities for more computationally expensive scheduling algorithms than what is traditionally considered for device-level real-time control sub-systems. In this paper, we review recent research conducted on collaborative scheduling algorithms in such systems that are subject to dynamic behavior such as transient and sustained resource overloads, arbitrary activity arrivals, and arbitrary node failures and message loss. We show that collaborative scheduling algorithms have an advantage over non-collaborative scheduling algorithms.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"141-142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124129839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In an integration system of RFID and wireless sensor network (WSN), RFID is used to identify objects while WSN can provide context environment information of these objects. Thus, it increases system intelligent in pervasive computing. We propose the EPC sensor network (ESN) architecture as an integration system of RFID and WSN. This ESN architecture is based on EPCglobal architecture, the de facto international standard for RFID. The core of ESN is the middleware part which is also implemented in our work. In this paper, complex event processing (CEP) technology is used in our ESN middleware which can handle large volume of events from distributed RFID and sensor readers in real time. Through filtering, grouping, aggregating and constructing complex event, ESN middleware provides a more meaningful report for the clients and increases system automation.
{"title":"Complex Event Processing in EPC Sensor Network Middleware for Both RFID and WSN","authors":"Weixin Wang, Jongwoo Sung, Daeyoung Kim","doi":"10.1109/ISORC.2008.59","DOIUrl":"https://doi.org/10.1109/ISORC.2008.59","url":null,"abstract":"In an integration system of RFID and wireless sensor network (WSN), RFID is used to identify objects while WSN can provide context environment information of these objects. Thus, it increases system intelligent in pervasive computing. We propose the EPC sensor network (ESN) architecture as an integration system of RFID and WSN. This ESN architecture is based on EPCglobal architecture, the de facto international standard for RFID. The core of ESN is the middleware part which is also implemented in our work. In this paper, complex event processing (CEP) technology is used in our ESN middleware which can handle large volume of events from distributed RFID and sensor readers in real time. Through filtering, grouping, aggregating and constructing complex event, ESN middleware provides a more meaningful report for the clients and increases system automation.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"16 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132089720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We give an introduction and survey of a formal modeling and verification approach that has been successfully applied to time-triggered protocols. This method allows us to capture and reason about real-time properties of distributed systems. It relies on the modeling concept of calendar similar to what has been used for a long time in discrete event simulation. It is also supported by efficient symbolic verification tools provided by the SAL environment. We present the basis of the modeling method and discuss two related verification approaches for analyzing complex, real-time distributed systems.
{"title":"Modeling and Verification of Time-Triggered Communication Protocols","authors":"M. Sorea, B. Dutertre, W. Steiner","doi":"10.1109/ISORC.2008.52","DOIUrl":"https://doi.org/10.1109/ISORC.2008.52","url":null,"abstract":"We give an introduction and survey of a formal modeling and verification approach that has been successfully applied to time-triggered protocols. This method allows us to capture and reason about real-time properties of distributed systems. It relies on the modeling concept of calendar similar to what has been used for a long time in discrete event simulation. It is also supported by efficient symbolic verification tools provided by the SAL environment. We present the basis of the modeling method and discuss two related verification approaches for analyzing complex, real-time distributed systems.","PeriodicalId":378715,"journal":{"name":"2008 11th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126397929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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