Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528780
H. Tokuda
In this paper, we describe operating system support for continuous media applications based on our experience of using the Real-Time Mach microkernel. We first address the limitations of the current workstation operating systems. Then, we discuss operating system support for continuous media from three different points of view: architectural support, resource management support, and programming support. Several Real-Time Mach examples are also discussed.
{"title":"Operating system support for continuous media applications-RT-Mach extensions","authors":"H. Tokuda","doi":"10.1109/RTCSA.1995.528780","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528780","url":null,"abstract":"In this paper, we describe operating system support for continuous media applications based on our experience of using the Real-Time Mach microkernel. We first address the limitations of the current workstation operating systems. Then, we discuss operating system support for continuous media from three different points of view: architectural support, resource management support, and programming support. Several Real-Time Mach examples are also discussed.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125047879","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528744
J. Busquets-Mataix, J. J. Serrano
Cache memories are commonly avoided in real-time systems because of their unpredictable behavior. Recently, some research has been done to obtain tighter bounds on the worst case execution time of cached programs. These techniques usually assume a non preemptive underlying system. However, some techniques can be applied to allow the use of caches in preemptive systems. This paper compares methods for dealing with extrinsic cache behavior (inter-task cache interference). Time-domain oriented methods (the inter-task cache interference is incorporated in the schedulability analysis) are compared to space-domain oriented ones (increase of the cache predictability by assigning private cache partitions to tasks). The obtained results bound the applicability domain for each method for a variety of hardware and workload configurations. The results can be used as design guidelines.
{"title":"The impact of extrinsic cache performance on predictability of real-time systems","authors":"J. Busquets-Mataix, J. J. Serrano","doi":"10.1109/RTCSA.1995.528744","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528744","url":null,"abstract":"Cache memories are commonly avoided in real-time systems because of their unpredictable behavior. Recently, some research has been done to obtain tighter bounds on the worst case execution time of cached programs. These techniques usually assume a non preemptive underlying system. However, some techniques can be applied to allow the use of caches in preemptive systems. This paper compares methods for dealing with extrinsic cache behavior (inter-task cache interference). Time-domain oriented methods (the inter-task cache interference is incorporated in the schedulability analysis) are compared to space-domain oriented ones (increase of the cache predictability by assigning private cache partitions to tasks). The obtained results bound the applicability domain for each method for a variety of hardware and workload configurations. The results can be used as design guidelines.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116013707","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528777
Y. Kokusho, N. Doi
When scheduling realtime parallel tasks onto multiprocessor systems, it is very important to optimize the computing resource allocations to those tasks using load-distribution mechanisms. This paper proposes a static load-distribution mechanism, called the Double-Layered Load-Distribution (DLLD) mechanism, which schedules hard realtime parallel computing tasks. Due to the nature of the hard realtime computation, the deadlines of task executions must be previously analysed and perfectly satisfied. For this reason, static load-distribution schemes are preferred to dynamic ones. In order to optimize the scheduling results with respect to various types of parallel computing tasks and various architectures of parallel-processor hardware, the DLLD mechanism is comprised of two functional layers: the DF/IHS scheduler (the upper layer) and the DPSTS (the lower layer).
{"title":"Scheduling hard-realtime parallel tasks onto the processor network with wrapped mesh topology","authors":"Y. Kokusho, N. Doi","doi":"10.1109/RTCSA.1995.528777","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528777","url":null,"abstract":"When scheduling realtime parallel tasks onto multiprocessor systems, it is very important to optimize the computing resource allocations to those tasks using load-distribution mechanisms. This paper proposes a static load-distribution mechanism, called the Double-Layered Load-Distribution (DLLD) mechanism, which schedules hard realtime parallel computing tasks. Due to the nature of the hard realtime computation, the deadlines of task executions must be previously analysed and perfectly satisfied. For this reason, static load-distribution schemes are preferred to dynamic ones. In order to optimize the scheduling results with respect to various types of parallel computing tasks and various architectures of parallel-processor hardware, the DLLD mechanism is comprised of two functional layers: the DF/IHS scheduler (the upper layer) and the DPSTS (the lower layer).","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"245 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116390581","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528762
H. Kopetz
{"title":"Fundamental Conflicts in the Design of Real-Time Protocols","authors":"H. Kopetz","doi":"10.1109/RTCSA.1995.528762","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528762","url":null,"abstract":"","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129498244","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528769
Morikazu Takegaki
The "Diaspect", the middleware package we have developed, provides basic industrial computing services common to various ICS applications. The Diaspect family includes a real-time data service that supports the programming of reliable hard real-time data processing, a man-machine service that realizes advanced man-machine functions for sophisticated plant operation, a distributed database middleware that manages the consistency of the distributed database and provides user specific views. We extracted these middleware services based on the analysis of many ICS applications. The author describes the concepts behind the development of the Diaspect, and outlines functions of principal middlewares.
{"title":"The middleware services for industrial computer systems","authors":"Morikazu Takegaki","doi":"10.1109/RTCSA.1995.528769","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528769","url":null,"abstract":"The \"Diaspect\", the middleware package we have developed, provides basic industrial computing services common to various ICS applications. The Diaspect family includes a real-time data service that supports the programming of reliable hard real-time data processing, a man-machine service that realizes advanced man-machine functions for sophisticated plant operation, a distributed database middleware that manages the consistency of the distributed database and provides user specific views. We extracted these middleware services based on the analysis of many ICS applications. The author describes the concepts behind the development of the Diaspect, and outlines functions of principal middlewares.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"726 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133283179","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528772
Tatsuhiro Tsuchiya, Y. Kakuda, T. Kikuno
In multiprocessors used for implementing real-time applications, it is strongly required to ensure that tasks' deadlines are met in spite of faults. In this paper, we discuss fault-tolerant task scheduling techniques in real-time multiprocessor systems where aperiodic tasks arrive dynamically. For fault-tolerance, multiple copies of each task have to be scheduled on distinct processors in such systems. The authors propose a new technique for efficiently scheduling copies of tasks having small laxity. Then, we integrate our technique with previous work and develop a new scheduling algorithm, removing the assumption on task laxity. Simulation results show the effectiveness of our technique.
{"title":"A new fault-tolerant scheduling technique for real-time multiprocessor systems","authors":"Tatsuhiro Tsuchiya, Y. Kakuda, T. Kikuno","doi":"10.1109/RTCSA.1995.528772","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528772","url":null,"abstract":"In multiprocessors used for implementing real-time applications, it is strongly required to ensure that tasks' deadlines are met in spite of faults. In this paper, we discuss fault-tolerant task scheduling techniques in real-time multiprocessor systems where aperiodic tasks arrive dynamically. For fault-tolerance, multiple copies of each task have to be scheduled on distinct processors in such systems. The authors propose a new technique for efficiently scheduling copies of tasks having small laxity. Then, we integrate our technique with previous work and develop a new scheduling algorithm, removing the assumption on task laxity. Simulation results show the effectiveness of our technique.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130195075","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528753
Sungyoung Lee, Hyungill Kim, Jongwon Lee
In this paper, we present a joint scheduling of hard deadline periodic and soft deadline aperiodic tasks in dynamic-priority systems. The proposed algorithm has extended the fixed-critical task indicating (CTI) algorithm developed by the authors previously (1995). The dynamic-CTI algorithm is operated in such a way that dynamic-priority assignment strategy for a given periodic task set and the information on a deadlinewise preassignment table, called dynamic-CTI table, are mixed dynamically according to the aperiodic tasks' arrivals at runtime. The algorithm has a predictability and a less computational complexity in calculating the slacks since it uses the dynamic-CTI table. Our simulation study shows that the dynamic-CTI scheduling has better performance than the fixed-CTI algorithm which is even better than the slack stealing algorithms, especially under a heavy, transient overload.
{"title":"A soft aperiodic task scheduling algorithm in dynamic-priority systems","authors":"Sungyoung Lee, Hyungill Kim, Jongwon Lee","doi":"10.1109/RTCSA.1995.528753","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528753","url":null,"abstract":"In this paper, we present a joint scheduling of hard deadline periodic and soft deadline aperiodic tasks in dynamic-priority systems. The proposed algorithm has extended the fixed-critical task indicating (CTI) algorithm developed by the authors previously (1995). The dynamic-CTI algorithm is operated in such a way that dynamic-priority assignment strategy for a given periodic task set and the information on a deadlinewise preassignment table, called dynamic-CTI table, are mixed dynamically according to the aperiodic tasks' arrivals at runtime. The algorithm has a predictability and a less computational complexity in calculating the slacks since it uses the dynamic-CTI table. Our simulation study shows that the dynamic-CTI scheduling has better performance than the fixed-CTI algorithm which is even better than the slack stealing algorithms, especially under a heavy, transient overload.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"574 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122932185","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528765
Heejo Lee, K. Toda, Jong Kim, K. Nishida, E. Takahashi, Y. Yamaguchi
This paper presents a performance comparison of real-time system architectures. A discrete event-driven, task-based simulator is developed for evaluating the performance of parallel and distributed real-time systems. Real-time system components such as processor, network architectures, and scheduling policy are included in the simulator. Simulation results show that priority-based communication and scheduling are more suitable for real-time systems than FIFO-based. The strategy of having a dedicated processor, which produces no effect on task execution by scheduling and packet/interrupt handling, is proven to enhance schedulability and predictability. This paper suggests a method for finding an appropriate real-time architecture for users having real-time requirements through the performance prediction of real-time systems.
{"title":"Performance comparison of real-time architectures using simulation","authors":"Heejo Lee, K. Toda, Jong Kim, K. Nishida, E. Takahashi, Y. Yamaguchi","doi":"10.1109/RTCSA.1995.528765","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528765","url":null,"abstract":"This paper presents a performance comparison of real-time system architectures. A discrete event-driven, task-based simulator is developed for evaluating the performance of parallel and distributed real-time systems. Real-time system components such as processor, network architectures, and scheduling policy are included in the simulator. Simulation results show that priority-based communication and scheduling are more suitable for real-time systems than FIFO-based. The strategy of having a dedicated processor, which produces no effect on task execution by scheduling and packet/interrupt handling, is proven to enhance schedulability and predictability. This paper suggests a method for finding an appropriate real-time architecture for users having real-time requirements through the performance prediction of real-time systems.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124109864","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528767
Hiroshi Koide
This paper proposes a new real-time garbage collection that always preserves the order of object creation. Some programming languages and application programs need to preserve the generated order of objects. The proposed method is the first type of the garbage collection that can be used to make them run in real-time. Since the generated order preserving scavenging garbage collection is partly employed, the complexity of the proposed method is not related to the heap size. The requirements for the real-time processing is also presented.
{"title":"The generated order preserving real-time garbage collection","authors":"Hiroshi Koide","doi":"10.1109/RTCSA.1995.528767","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528767","url":null,"abstract":"This paper proposes a new real-time garbage collection that always preserves the order of object creation. Some programming languages and application programs need to preserve the generated order of objects. The proposed method is the first type of the garbage collection that can be used to make them run in real-time. Since the generated order preserving scavenging garbage collection is partly employed, the complexity of the proposed method is not related to the heap size. The requirements for the real-time processing is also presented.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124996325","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}
Pub Date : 1995-10-25DOI: 10.1109/RTCSA.1995.528759
S. Cha, Beomyeong Park, Soondong Lee, Sumin Song, J. Park, J. S. Lee, Sumin Park, D. Hur, Gi-Chang Kim
Many applications, such as telecommunication, process control, and virtual reality, require real-time access to database. Main-memory DBMS, which becomes feasible with the increasing availability of large and relatively cheap memory, can provide better performance than disk-based systems for real-time applications. This paper presents an overall architecture of M/sup 2/RT, a main-memory real-time DBMS, and an object-oriented design of its storage system called M/sup 2/RTSS. M/sup 2/RTSS provides classes that implement the core functionality of storage management, real-time transaction scheduling, and recovery. Implemetation-specific information is encapsulated in these classes and extensions can be made by inheritance. With object-oriented features, M/sup 2/RTSS can easily incorporate new development in application requirements and the result of ongoing research in real-time systems.
{"title":"Object-oriented design of main-memory DBMS for real-time applications","authors":"S. Cha, Beomyeong Park, Soondong Lee, Sumin Song, J. Park, J. S. Lee, Sumin Park, D. Hur, Gi-Chang Kim","doi":"10.1109/RTCSA.1995.528759","DOIUrl":"https://doi.org/10.1109/RTCSA.1995.528759","url":null,"abstract":"Many applications, such as telecommunication, process control, and virtual reality, require real-time access to database. Main-memory DBMS, which becomes feasible with the increasing availability of large and relatively cheap memory, can provide better performance than disk-based systems for real-time applications. This paper presents an overall architecture of M/sup 2/RT, a main-memory real-time DBMS, and an object-oriented design of its storage system called M/sup 2/RTSS. M/sup 2/RTSS provides classes that implement the core functionality of storage management, real-time transaction scheduling, and recovery. Implemetation-specific information is encapsulated in these classes and extensions can be made by inheritance. With object-oriented features, M/sup 2/RTSS can easily incorporate new development in application requirements and the result of ongoing research in real-time systems.","PeriodicalId":111365,"journal":{"name":"Proceedings Second International Workshop on Real-Time Computing Systems and Applications","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127592716","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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