Leibniz Trans. Embed. Syst.最新文献_第3页

Real-Time Scheduling on Uni- and Multiprocessors based on Priority Promotions 基于优先级提升的单处理器和多处理器实时调度

Leibniz Trans. Embed. Syst. Pub Date : 2016-06-10 DOI: 10.4230/LITES-v003-i001-a002

R. Pathan

{"title":"Real-Time Scheduling on Uni- and Multiprocessors based on Priority Promotions","authors":"R. Pathan","doi":"10.4230/LITES-v003-i001-a002","DOIUrl":"https://doi.org/10.4230/LITES-v003-i001-a002","url":null,"abstract":"This paper addresses the problem of real-time scheduling of a set of sporadic tasks on uni- and multiprocessor platform based on priority promotion. A new preemptive scheduling algorithm, called Fixed-Priority with Priority Promotion (FPP), is proposed. In FPP scheduling, tasks are executed similar to traditional fixed-priority (FP) scheduling but the priority of some tasks are promoted at fixed time interval (called, promotion point) relative to the release time of each job. A policy called Increase Priority at Deadline Difference (IPDD) to compute the promotion points and promoted priorities for each task is proposed. FPP scheduling prioritizes jobs according to Earliest-Deadline-First (EDF) priority when all tasks' priorities follow IPDD policy. It is known that managing (i.e., inserting and removing) jobs in the ready queue of traditional EDF scheduler is more complex than that of FP scheduler. To avoid such problem in FPP scheduling, a simple data structure and efficient operations to manage jobs in the ready queue are proposed. In addition, techniques for implementing priority promotions with and without the use of a hardware timer are proposed. Finally, an effective scheme to reduce the average number of priority promotions is proposed: if a task set is not schedulable using traditional FP scheduling, then promotion points are assigned only to those tasks that need them to meet the deadlines; otherwise, tasks are assigned traditional fixed priorities without any priority promotion. Empirical investigation shows the effectiveness of the proposed scheme in reducing overhead on uniprocessor and in accepting larger number of task sets in comparison to that of using state-of-the-art global schedulability tests for multiprocessors.","PeriodicalId":376325,"journal":{"name":"Leibniz Trans. Embed. Syst.","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129678550","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}

引用次数: 2

Programming Language Constructs Supporting Fault Tolerance 支持容错的编程语言结构

Leibniz Trans. Embed. Syst. Pub Date : 2016-06-10 DOI: 10.4230/LITES-v003-i001-a001

Christina K. Houben, Sebastian Houben

引用次数: 0

From Dataflow Specification to Multiprocessor Partitioned Time-triggered Real-time Implementation 从数据流规范到多处理器分区时间触发实时实现

Leibniz Trans. Embed. Syst. Pub Date : 2015-11-30 DOI: 10.4230/LITES-v002-i002-a001

Thomas Carle, D. Potop-Butucaru, Y. Sorel, D. Lesens

{"title":"From Dataflow Specification to Multiprocessor Partitioned Time-triggered Real-time Implementation","authors":"Thomas Carle, D. Potop-Butucaru, Y. Sorel, D. Lesens","doi":"10.4230/LITES-v002-i002-a001","DOIUrl":"https://doi.org/10.4230/LITES-v002-i002-a001","url":null,"abstract":"Our objective is to facilitate the development of complex time-triggered systems by automating the allocation and scheduling steps. We show that full automation is possible while taking into account the elements of complexity needed by a complex embedded control system. More precisely, we consider deterministic functional specifications provided (as often in an industrial setting) by means of synchronous data-flow models with multiple modes and multiple relative periods. We first extend this functional model with an original real-time characterization that takes advantage of our time-triggered framework to provide a simpler representation of complex end-to-end flow requirements. We also extend our specifications with additional non-functional properties specifying partitioning, allocation, and preemptability constraints. Then, we provide novel algorithms for the off-line scheduling of these extended specifications onto partitioned time-triggered architectures a la ARINC 653. The main originality of our work is that it takes into account at the same time multiple complexity elements: various types of non-functional properties (real-time, partitioning, allocation, preemptability) and functional specifications with conditional execution and multiple modes. Allocation of time slots/windows to partitions can be fully or partially provided, or synthesized by our tool. Our algorithms allow the automatic allocation and scheduling onto multi-processor (distributed) systems with a global time base, taking into account communication costs. We demonstrate our technique on a model of space flight software system with strong real-time determinism requirements.","PeriodicalId":376325,"journal":{"name":"Leibniz Trans. Embed. Syst.","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114911794","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}

引用次数: 35

Quantitative Analysis of Consistency in NoSQL Key-Value Stores NoSQL键值存储一致性的定量分析

Leibniz Trans. Embed. Syst. Pub Date : 2015-09-01 DOI: 10.4230/LITES-v004-i001-a003

Si Liu, Jatin Ganhotra, Muntasir Raihan Rahman, Son Nguyen, Indranil Gupta, J. Meseguer

引用次数: 31

More General Optimal Offset Assignment 更一般的最优偏移分配

Leibniz Trans. Embed. Syst. Pub Date : 2015-06-02 DOI: 10.4230/LITES-v002-i001-a002

Sven Mallach

引用次数: 3

Randomized Caches Can Be Pretty Useful to Hard Real-Time Systems 随机缓存对于硬实时系统非常有用

Leibniz Trans. Embed. Syst. Pub Date : 2015-03-23 DOI: 10.4230/LITES-v002-i001-a001

E. Mezzetti, Marco Ziccardi, T. Vardanega, J. Abella, E. Quiñones, F. Cazorla

{"title":"Randomized Caches Can Be Pretty Useful to Hard Real-Time Systems","authors":"E. Mezzetti, Marco Ziccardi, T. Vardanega, J. Abella, E. Quiñones, F. Cazorla","doi":"10.4230/LITES-v002-i001-a001","DOIUrl":"https://doi.org/10.4230/LITES-v002-i001-a001","url":null,"abstract":"Cache randomization per se, and its viability for probabilistic timing analysis (PTA) of critical real-time systems, are receiving increasingly close attention from the scientific community and the industrial practitioners. In fact, the very notion of introducing randomness and probabilities in time-critical systems has caused strenuous debates owing to the apparent clash that this idea has with the strictly deterministic view traditionally held for those systems. A paper recently appeared in LITES (Reineke, J. (2014). Randomized Caches Considered Harmful in Hard Real-Time Systems. LITES, 1(1), 03:1-03:13.) provides a critical analysis of the weaknesses and risks entailed in using randomized caches in hard real-time systems. In order to provide the interested reader with a fuller, balanced appreciation of the subject matter, a critical analysis of the benefits brought about by that innovation should be provided also. This short paper addresses that need by revisiting the array of issues addressed in the cited work, in the light of the latest advances to the relevant state of the art. Accordingly, we show that the potential benefits of randomized caches do offset their limitations, causing them to be - when used in conjunction with PTA - a serious competitor to conventional designs.","PeriodicalId":376325,"journal":{"name":"Leibniz Trans. Embed. Syst.","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122129318","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}

引用次数: 31

Implementing Mixed-criticality Systems Upon a Preemptive Varying-speed Processor 在抢占式变速处理器上实现混合临界系统

Leibniz Trans. Embed. Syst. Pub Date : 2014-11-17 DOI: 10.4230/LITES-v001-i002-a003

Zhishan Guo, Sanjoy Baruah

{"title":"Implementing Mixed-criticality Systems Upon a Preemptive Varying-speed Processor","authors":"Zhishan Guo, Sanjoy Baruah","doi":"10.4230/LITES-v001-i002-a003","DOIUrl":"https://doi.org/10.4230/LITES-v001-i002-a003","url":null,"abstract":"A mixed criticality (MC) workload consists of components of varying degrees of importance (or \"criticalities\"); the more critical components typically need to have their correctness validated to greater levels of assurance than the less critical ones. The problem of executing such a MC workload upon a preemptive processor whose effective speed may vary during run-time, in a manner that is not completely known prior to run-time, is considered. Such a processor is modeled as being characterized by several execution speeds: a normal speed and several levels of degraded speed. Under normal circumstances it will execute at or above its normal speed; conditions during run-time may cause it to execute slower. It is desired that all components of the MC workload execute correctly under normal circumstances. If the processor speed degrades, it should nevertheless remain the case that the more critical components execute correctly (although the less critical ones need not do so). In this work, we derive an optimal algorithm for scheduling MC workloads upon such platforms; achieving optimality does not require that the processor be able to monitor its own run-time speed. For the sub-case of the general problem where there are only two criticality levels defined, we additionally provide an implementation that is asymptotically optimal in terms of run-time efficiency.","PeriodicalId":376325,"journal":{"name":"Leibniz Trans. Embed. Syst.","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133792241","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}

引用次数: 7

Computation Offloading for Frame-Based Real-Time Tasks under Given Server Response Time Guarantees 给定服务器响应时间保证下基于帧的实时任务的计算卸载

Leibniz Trans. Embed. Syst. Pub Date : 2014-11-14 DOI: 10.4230/LITES-v001-i002-a002

Anas Toma, Jian-Jia Chen

引用次数: 6

Blocking Optimality in Distributed Real-Time Locking Protocols 分布式实时锁定协议中的阻塞优化

Leibniz Trans. Embed. Syst. Pub Date : 2014-09-12 DOI: 10.4230/LITES-v001-i002-a001

Björn B. Brandenburg

{"title":"Blocking Optimality in Distributed Real-Time Locking Protocols","authors":"Björn B. Brandenburg","doi":"10.4230/LITES-v001-i002-a001","DOIUrl":"https://doi.org/10.4230/LITES-v001-i002-a001","url":null,"abstract":"Lower and upper bounds on the maximum priority inversion blocking (pi-blocking) that is generally unavoidable in distributed multiprocessor real-time locking protocols (where resources may be accessed only from specific synchronization processors) are established. Prior work on suspension-based shared-memory multiprocessor locking protocols (which require resources to be accessible from all processors) has established asymptotically tight bounds of Ω(m) and Ω(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively, where m denotes the total number of processors and n denotes the number of tasks. In this paper, it is shown that, in the case of distributed semaphore protocols, there exist two different task allocation scenarios that give rise to distinct lower bounds. In the case of co-hosted task allocation, where application tasks may also be assigned to synchronization processors (i.e., processors hosting critical sections), Ω(Φ · n) maximum pi-blocking is unavoidable for some tasks under any locking protocol under both suspension-aware and suspension-oblivious schedulability analysis, where Φ denotes the ratio of the maximum response time to the shortest period. In contrast, in the case of disjoint task allocation (i.e., if application tasks may not be assigned to synchronization processors), only Ω(m) and Ω(n) maximum pi-blocking is fundamentally unavoidable under suspension-oblivious and suspension-aware analysis, respectively, as in the shared-memory case. These bounds are shown to be asymptotically tight with the construction of two new distributed real-time locking protocols that ensure O(m) and O(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively.","PeriodicalId":376325,"journal":{"name":"Leibniz Trans. Embed. Syst.","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133615685","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}

引用次数: 15

Randomized Caches Considered Harmful in Hard Real-Time Systems 随机缓存在硬实时系统中是有害的

Leibniz Trans. Embed. Syst. Pub Date : 2014-06-10 DOI: 10.4230/LITES-v001-i001-a003

J. Reineke

引用次数: 44