{"title":"Hard real-time preemptively scheduling with high context switch cost","authors":"J. Echagüe, I. Ripoll, A. Crespo","doi":"10.1109/EMWRTS.1995.514310","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514310","url":null,"abstract":"One of the most important aspects in the development of real-time systems is the scheduling policy to guarantee the response time of a task with timing constraints. Some real-time scheduling techniques use the advantage of stack scheduler properties to bound the number of context switches. In general purpose real-time systems, the context switch does not introduce a significant overhead in the system execution, so their importance in the analysis is not relevant. However, in some applications such as multimedia where the tasks exhibit a very high context switch cost, their importance could be crucial. In this case, the context switch is mainly due to the latency time of the I/O devices. In this paper, an analytic model is presented to calculate off-line the number of preemptions which a set of periodic tasks suffer, scheduled by a static (Rate Monotonic, Deadline Monotonic) and a dynamic (Earliest Deadline First) scheduler. Moreover, the necessary and sufficient conditions to construct a task set in which a subset will never be preempted being scheduled under the scheduling policies described is shown. Finally, an evaluation and comparison of both approaches is developed.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122567632","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":"Pessimistic Deadline Ceiling Protocol: a concurrency control protocol under earliest deadline first scheduling","authors":"Joo-Yong Kim, K. Koh","doi":"10.1109/EMWRTS.1995.514296","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514296","url":null,"abstract":"Priority inversion is one of the major sources which makes the real-time system unpredictable. The Stack Resource Policy (SRP) and the Dynamic Priority Ceiling Protocol (Dpcp) are two representative protocols that solve the priority inversion problem under earliest deadline first scheduling (EDF). Dpcp yields better performance but incurs more overhead than SRP. We propose a new algorithm called the Pessimistic Priority Ceiling Protocol (PDCP). PDCP is based on the notions of the inactive task and the pessimistic deadline, which are defined in the paper. PDCP uses the dynamic value for the priority to access a shared resource, and uses the static value for determining the resource ceiling. PDCP yields comparable performance with Dpcp yet incurs less overhead than Dpcp. When compared to SRP, PDCP yields better performance at a slightly higher overhead. In particular, PDCP has the same overhead as SRP if the depth of the resource nesting is 1.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125102372","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":"A new method for optimization of allocation and scheduling in real time applications","authors":"M. Coli, P. Palazzari","doi":"10.1109/EMWRTS.1995.514320","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514320","url":null,"abstract":"Performance improvements achievable through parallel processing are useful in real time (RT) environments. The paper describes a method to map (i.e. allocate and schedule) a program with some RT constraints into a parallel system. We formulate the mapping problem as a minimization problem, defining a new cost function whose minimization leads to the optimal mapping of the program into the parallel system. The searching space over which the minimization must be carried out is defined; this space encloses all the feasible allocation and scheduling modalities for the program in the parallel system. The minimization is carried out through a simulated annealing algorithm, so we define an adjacency criterion on the searching space. Some examples illustrating the capabilities of the proposed method are presented.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"24 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124109230","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":"Stochastic Petri net evaluation techniques in plant automation: tuning performance indices for distributed applications","authors":"O. Botti, L. Capra, C. Bergomi","doi":"10.1109/EMWRTS.1995.514324","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514324","url":null,"abstract":"We report the results of an investigation aiming at experimenting the use of Generalized Stochastic Petri Nets (GSPN), a formal method which allows to model a concurrent application with an explicit representation of timing constraints, and to evaluate its performance over a target parallel architecture. We focus on the definition and use of a set of indices suitable to characterise an application in terms of its performance and to support its mapping over a parallel architecture, guided by the training over a case study taken from the ENEL R&D activity in real time plant automation. The effort spent to extend and to bring a relatively consolidated theory (GSPN) near to the industrial user needs, may be seen as the first original contribution of the paper.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130906805","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":"Transforming designs towards implementations","authors":"M. Kaaramees","doi":"10.1109/EMWRTS.1995.514312","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514312","url":null,"abstract":"We are interested in constructing safety-critical systems from their requirements specification. Our approach is the following: we start with requirements formalized in Duration Calculus (DC). These requirements are transformed to another form in DC, expressing the design of the system. The design is then transformed to a joint action system expressed in DisCo language. The specifications in DC emphasize properties the system must have, whereas the joint action system is closer to description how the system must be implemented. The philosophy is that all the involved transformations must be proven correct. This paper focuses on the transformation from a design in DC to a joint action system in DisCo.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124026646","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":"A scheduling problem language","authors":"Mikko Levanto","doi":"10.1109/EMWRTS.1995.514292","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514292","url":null,"abstract":"A language for specification of the details of a scheduling problem is presented. First experiments indicate that the language can be used to express actual scheduling problems. Some deficiencies were detected but they can be fixed while keeping the general structure of the language.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130401264","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":"Measuring the real-time operating system performance","authors":"K. Sacha","doi":"10.1109/EMWRTS.1995.514289","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514289","url":null,"abstract":"Tests for measuring the real time operating system performance belong to the software technology. They give quantitative measures for the most important characteristics and allow the implementer to compare the efficiency of various operating systems. The paper presents a set of simple tests for measuring the real time operating system characteristics. The tests require no specialized hardware, and are based on direct measuring of the duration of execution of sequences of system functions. All tests described in the paper have been applied to measure the efficiency of a distributed operating system QNX. The measurements include the speed of intertask communication through messages, proxies and signals, and the speed of task switching and timer interrupt handling. The results are presented in a series of easily readable tables.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130555770","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":"A Q-model approach to decomposition and aggregation of specifications of real-time systems","authors":"R. Paluoja","doi":"10.1109/EMWRTS.1995.514314","DOIUrl":"https://doi.org/10.1109/EMWRTS.1995.514314","url":null,"abstract":"New application areas and the increasing complexity of problems to be solved with real-time systems have led to a corresponding decrease in the probability of designing a correct solution. In this paper a Q-model approach to the problem of dealing with complexity of the specification process, specifically some aspects of decomposition and aggregation, is discussed. The evolutionary development of a specification is recorded in the form of a heredity tree. The heredity tree is built up by decomposing, or aggregating, processes in the specification. To guarantee the correct data interfaces, and the equivalence of dynamic properties between specifications at different levels of detail (especially, when all timing parameters are not yet completely specified), dummy processes, to represent different time parameters and perform specific functions, are introduced.","PeriodicalId":156501,"journal":{"name":"Proceedings Seventh Euromicro Workshop on Real-Time Systems","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131201429","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}