{"title":"SSP: A semantics-based protocol for real-time data access","authors":"Tei-Wei Kuo, A. Mok","doi":"10.1109/REAL.1993.393513","DOIUrl":"https://doi.org/10.1109/REAL.1993.393513","url":null,"abstract":"We propose a class of real-time data access protocols called SSP (Similarity Stack Protocol). The correctness of SSP schedules is justified by the concept of similarity which allows different but sufficiently timely data to be used in a computation without adversely affecting the outcome. SSP schedules are deadlock-free, subject to limited blocking and do not use locks. We give a schedulability bound for SSP and also report simulation results which show that SSP is especially useful for scheduling real-time data access on multiprocessor systems. Finally, we present a variation of SSP which can be implemented in an autonomous fashion in the sense that scheduling decisions can be made with local information only.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131132383","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}
{"title":"On-line scheduling of hard deadline aperiodic tasks in fixed-priority systems","authors":"S. R. Thuel, J. Lehoczky","doi":"10.1109/REAL.1993.393504","DOIUrl":"https://doi.org/10.1109/REAL.1993.393504","url":null,"abstract":"This paper presents a new algorithm for the on-line scheduling of hard deadline aperiodic tasks in a real-time system in which hard deadline periodic tasks are scheduled using a fixed priority algorithm. The algorithm for jointly scheduling the periodic and aperiodic tasks extends the slack stealing algorithm introduced by Lehoczky and Ramos-Thuel (1992), and thus provides the largest amount of time for aperiodic task processing subject to meeting all periodic task deadlines. The analysis permits the periodic tasks to consist of a set of serially executed subtasks each of which has its own fixed execution priority as defined by (Gonzalez Harbour et al., (1991)) Thus the model permits the direct inclusion of operating system functions as well as certain types of synchronization protocols directly into the schedulability analysis. The methods provide a unified framework for dealing with several related problems including: reclaiming unused periodic and aperiodic execution time, load shedding, balancing hard and soft aperiodic execution time and coping with transient overloads.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126875778","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}
{"title":"Automatic symbolic verification of embedded systems","authors":"R. Alur, T. Henzinger, Pei-Hsin Ho","doi":"10.1109/REAL.1993.393520","DOIUrl":"https://doi.org/10.1109/REAL.1993.393520","url":null,"abstract":"We present a model checking procedure and its implementation for the automatic verification of embedded systems. Systems are represented by hybrid automata - machines with finite control and real-valued variables modeling continuous environment parameters such as time, pressure, and temperature. System properties are specified in a real-time temporal logic and verified by symbolic computation. The verification procedure, implemented in Mathematica, is used to prove digital controllers and distributed algorithms correct. The verifier checks safety, liveness, time-bounded, and duration properties of hybrid automata.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"8 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129622394","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}
{"title":"Object-based semantic real-time concurrency control","authors":"L. DiPippo, V. Wolfe","doi":"10.1109/REAL.1993.393512","DOIUrl":"https://doi.org/10.1109/REAL.1993.393512","url":null,"abstract":"This paper presents a technique that is capable of supporting two major requirements for concurrency control in real-time databases; data temporal consistency, and data logical consistency, as well as tradeoffs between these requirements. Our technique is based upon a real-time object-oriented database model in which each object has its own unique compatibility function that expresses the conditional compatibility of any two potential concurrent operations on the object. The conditions use the semantics of the object, such as allowable imprecision, along with current system state, such as time and the active operations on the object. Our concurrency control technique enforces that allowable concurrency expressed by the compatibility function by using semantic locking controlled by each individual object. The real-time object-oriented database model and process of evaluating the compatibility function to grant semantic locks are described.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121469247","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}
{"title":"Real-time issues in computer music","authors":"R. Dannenberg, D. Jameson","doi":"10.1109/REAL.1993.393491","DOIUrl":"https://doi.org/10.1109/REAL.1993.393491","url":null,"abstract":"Real-time systems are essential to computer music, and new developments in scheduling, operating systems, and languages are certain to find applications in music. At the same time, we believe the issues that arise in computer music should be of interest to designers of real-time systems. Computer music systems are demanding and complex, and require a large degree of flexibility to support the creative goals of musicians. Musicians and composers were working in the \"real-time business\" long before the computer, and we think the art and science of music-making has much to offer.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126214901","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}
Minsuk Lee, S. Min, C. Park, Young Hyun Bae, Heonshik Shin, Chong-Sang Kim
{"title":"A dual-mode instruction prefetch scheme for improved worst case and average case program execution times","authors":"Minsuk Lee, S. Min, C. Park, Young Hyun Bae, Heonshik Shin, Chong-Sang Kim","doi":"10.1109/REAL.1993.393511","DOIUrl":"https://doi.org/10.1109/REAL.1993.393511","url":null,"abstract":"One of the obstacles to using RISC processors in a hard real-time environment is the unpredictability of caches. This unpredictability stems from basing them on a design that tries to optimize the average case execution time. We propose a dual mode instruction prefetch scheme as an alternative to instruction caching schemes. In the proposed scheme, a thread is associated with each instruction block. The thread indicates the instruction block that is to be prefetched once the block containing it is accessed by the processor. The proposed scheme operates in two different modes: real-time and non real-time modes. In the real-time mode, the prefetching of instruction blocks is made in the direction that improves the worst case execution time. For this purpose, the thread is generated by the compiler through an analysis of the worst case execution path. In the non real-time mode, the thread is dynamically updated so that it indicates the instruction block that is most likely to be accessed next is the block that was previously accessed after the present block. Therefore, the thread is made to point to such a block in the non real-time mode. The above tailoring of thread information is on a task basis and, therefore, each task in the system can choose its own mode depending on its needs. Typically real-time tasks choose the real-time mode for an improved worst case execution time whereas non time critical tasks choose the non real-time mode for an improved average case execution time. This paper shows, through analysis using a timing tool, that the proposed scheme significantly (up to 45%) improves the predicted worst case execution time in the real-time mode as compared with no prefetching scheme.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133331515","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}
{"title":"Specification and verification of a distributed real-time arbitration protocol","authors":"J. Hooman","doi":"10.1109/REAL.1993.393488","DOIUrl":"https://doi.org/10.1109/REAL.1993.393488","url":null,"abstract":"To specify and verify distributed real-time systems, we use a formalism based on Hoare triples. The framework has been adapted to deal with safety as well as liveness properties, and a compositional proof method has been formulated. The formalism is applied to a distributed real-time arbitration protocol in which concurrent modules compete to get control over a common bus.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121022969","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}
{"title":"Using dynamic adjustment of serialization order for real-time database systems","authors":"Juhnyoung Lee, S. Son","doi":"10.1109/REAL.1993.393514","DOIUrl":"https://doi.org/10.1109/REAL.1993.393514","url":null,"abstract":"Studies concluded that for a variety of reasons, optimistic concurrency control appears well-suited to real-time database systems. Especially, they showed that in a real-time database system that discards tardy transactions, optimistic concurrency control outperforms locking. We show that the optimistic algorithms used in those studies incur restarts unnecessary to ensure data consistency. We present a new optimistic concurrency control algorithm that can avoid such unnecessary restarts by adjusting serialization order dynamically, and demonstrate that the new algorithm outperforms the previous ones over a wide range of system workload. It appears that this algorithm is a promising candidate for a basic concurrency control mechanism for real-time database systems.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125244422","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}
{"title":"Scheduling slack time in fixed priority pre-emptive systems","authors":"Robert I. Davis, K. Tindell, A. Burns","doi":"10.1109/REAL.1993.393496","DOIUrl":"https://doi.org/10.1109/REAL.1993.393496","url":null,"abstract":"This paper addresses the problem of jointly scheduling tasks with both hard and soft time constraints. We present a new analysis which builds upon previous research into slack stealing algorithms. Our analysis determines the maximum processing time which may be stolen from hard deadline periodic or sporadic tasks, without jeopardising their timing constraints. It extends to tasks with characteristics such as synchronization, release jitter and stochastic execution times, as well as forming the basis for a family of optimal and approximate slack stealing algorithms.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127632495","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}
{"title":"Highly multi-tasking real-time systems and their evaluation","authors":"T. Soneoka, Ayaru Oizumi, K. Suda","doi":"10.1109/REAL.1993.393493","DOIUrl":"https://doi.org/10.1109/REAL.1993.393493","url":null,"abstract":"Application systems in real-time processing fields, in addition to those systems whose most important requirement is to complete processing within a given response time, also include systems whose aims are to raise throughput within the response time restrictions, in which a high degree of multi-tasking is of primary importance. The paper makes proposals on task scheduling and OS functions in highly multi-tasking real-time processing domains, and outlines a research project presently being undertaken in NTT to study real-time OS performance evaluation methods geared to these domains.<<ETX>>","PeriodicalId":198313,"journal":{"name":"1993 Proceedings Real-Time Systems Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126218122","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}