2015 27th Euromicro Conference on Real-Time Systems最新文献

Experimental Evaluation of Optimal Schedulers Based on Partitioned Proportionate Fairness 基于分区比例公平性的最优调度的实验评价

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.18

Davide Compagnin, E. Mezzetti, T. Vardanega

{"title":"Experimental Evaluation of Optimal Schedulers Based on Partitioned Proportionate Fairness","authors":"Davide Compagnin, E. Mezzetti, T. Vardanega","doi":"10.1109/ECRTS.2015.18","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.18","url":null,"abstract":"The Quasi-Partitioning Scheduling algorithm optimally solves the problem of scheduling a feasible set of independent implicit-deadline sporadic tasks on a symmetric multiprocessor. It iteratively combines bin-packing solutions to determine a feasible task-to-processor allocation, splitting task loads as needed along the way so that the excess computation on one processor is assigned to a paired processor. Though different in formulation, QPS belongs in the same family of schedulers as RUN, which achieve optimality using a relaxed (partitioned) version of proportionate fairness. Unlike RUN, QPS departs from the dual schedule equivalence, thus yielding a simpler implementation with less use of global data structures. One might therefore expect that QPS should outperform RUN in the general case. Surprisingly instead, our implementation of QPS on LITMUS^RT invalidates this conjecture, showing that the QPS offline decisions may have an important influence on run-time performance. In this work, we present an extensive comparison between RUN and QPS, looking at both the offline and the online phases, to highlight their relative strengths and weaknesses.","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123980976","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: 5

Minimizing Cache Overhead via Loaded Cache Blocks and Preemption Placement 通过加载缓存块和抢占放置最小化缓存开销

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.22

John Cavicchio, Corey Tessler, N. Fisher

{"title":"Minimizing Cache Overhead via Loaded Cache Blocks and Preemption Placement","authors":"John Cavicchio, Corey Tessler, N. Fisher","doi":"10.1109/ECRTS.2015.22","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.22","url":null,"abstract":"Schedulability analysis for real-time systems has been the subject of prominent research over the past several decades. One of the key foundations of schedulability analysis is an accurate worst case execution time (WCET) measurement for each task. In real-time systems that support preemption, the cache related preemption delay (CRPD) can represent a significant component (up to 44% as documented in research literature) [1] -- [3] of variability to overall task WCET. Several methods have been employed to calculate CRPD with significant levels of pessimism that may result in a task set erroneously declared as non-schedulable. Furthermore, they do not take into account that CRPD cost is inherently a function of where preemptions actually occur. Our approach for computing CRPD via loaded cache blocks (LCBs) is more accurate in the sense that cache state reflects which cache blocks and the specific program locations where they are reloaded. Limited preemption models attempt to minimize preemption overhead (CRPD) by reducing the number of allowed preemptions and/or allowing preemption at program locations where the CRPD effect is minimized. These algorithms rely heavily on accurate CRPD measurements or estimation models in order to identify an optimal set of preemption points. Our approach improves the effectiveness of limited optimal preemption point placement algorithms by calculating the LCBs for each pair of adjacent preemptions to more accurately model task WCET and maximize schedulability as compared to existing preemption point placement approaches. We propose an optimal preemption point placement algorithm using dynamic programming. Lastly, we will demonstrate, using a case study, improved task set schedulability and optimal preemption point placement via our new LCB characterization.","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132009109","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

A Bailout Protocol for Mixed Criticality Systems 混合临界系统的救助协议

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.30

I. Bate, A. Burns, Robert I. Davis

引用次数: 57

Improved Deadline Miss Models for Real-Time Systems Using Typical Worst-Case Analysis 利用典型最坏情况分析改进实时系统的最后期限缺失模型

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.29

Wenbo Xu, Zain Alabedin Haj Hammadeh, A. Kröller, R. Ernst, Sophie Quinton

引用次数: 44

Timing Analysis of Fixed Priority Self-Suspending Sporadic Tasks 固定优先级自挂偶发任务的时序分析

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ecrts.2015.15

Geoffrey Nelissen, J. Fonseca, Gurulingesh Raravi, Vincent Nélis

引用次数: 47

Uniprocessor Feasibility of Sporadic Tasks with Constrained Deadlines Is Strongly coNP-Complete 具有约束截止日期的零星任务的单处理器可行性是强cp完全的

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.32

Pontus Ekberg, W. Yi

引用次数: 28

WCET(m) Estimation in Multi-core Systems Using Single Core Equivalence 基于单核等效的多核系统WCET(m)估计

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.23

R. Mancuso, R. Pellizzoni, M. Caccamo, L. Sha, H. Yun

{"title":"WCET(m) Estimation in Multi-core Systems Using Single Core Equivalence","authors":"R. Mancuso, R. Pellizzoni, M. Caccamo, L. Sha, H. Yun","doi":"10.1109/ECRTS.2015.23","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.23","url":null,"abstract":"Multi-core platforms represent the answer of the industry to the increasing demand for computational capabilities. From a real-time perspective, however, the inherent sharing of resources, such as memory subsystem and I/O channels, creates inter-core timing interference among critical tasks and applications deployed on different cores. As a result, modular per-core certification cannot be performed, meaning that: (1) current industrial engineering processes cannot be reused, (2) software developed and certified for single-core chips cannot be deployed on multi-core platforms as is. In this work, we propose the Single Core Equivalence (SCE) technology: a framework of OS-level techniques designed for commercial (COTS) architectures that exports a set of equivalent single-core virtual machines from a multi-core platform. This allows per-core schedulability results to be calculated in isolation and to hold when multiple cores of the system run in parallel. Thus, SCE allows each core of a multi-core chip to be considered as a conventional single-core chip, ultimately enabling industry to reuse existing software, schedulability analysis methodologies and engineering processes.","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129147691","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: 72

On-Line Data Link Layer Scheduling in Wireless Networked Control Systems 无线网络控制系统中的在线数据链路层调度

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.13

S. Hong, X. Hu, Tao Gong, Song Han

{"title":"On-Line Data Link Layer Scheduling in Wireless Networked Control Systems","authors":"S. Hong, X. Hu, Tao Gong, Song Han","doi":"10.1109/ECRTS.2015.13","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.13","url":null,"abstract":"Wireless networked control systems (WNCSs) are widely used in many applications. A key challenge in WNCSs is to develop efficient data link layer (DLL) scheduling algorithms to achieve reliable end-to-end real-time communication. Previous research typically assumes that the network communication schedule of WNCS, once constructed and distributed, stays unchanged, thus cannot handle dynamic variations which are unavoidable in many WNCSs. This paper considers the DLL scheduling problem in WNCSs, where external disturbances occur sporadically. An on-line framework, employing a rhythmic task model, is introduced to adjust the static schedule to respond to external disturbances. The approach determines the time duration to apply a dynamic schedule and generates the schedule for that time duration to minimize the impact of network dynamics on existing network flows. The effectiveness and efficiency of the proposed algorithm are validated by extensive simulation. Results indicate that the proposed approach outperforms existing work both in terms of the number of feasible task sets (between 11% and 41% increase on average) and the number of feasible periodic packets (between 122% and 128% increase on average).","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133249262","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: 20

A Computation Offloading Framework for Soft Real-Time Embedded Systems 软实时嵌入式系统的计算卸载框架

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.19

Yuchuan Liu, Cong Liu, Xia Zhang, Wei Gao, Liang He, Y. Gu

{"title":"A Computation Offloading Framework for Soft Real-Time Embedded Systems","authors":"Yuchuan Liu, Cong Liu, Xia Zhang, Wei Gao, Liang He, Y. Gu","doi":"10.1109/ECRTS.2015.19","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.19","url":null,"abstract":"Recent developments in embedded hardware have empowered human experiences through pervasive computing. While embedded systems are becoming more powerful, they still fall short when faced with users' growing desire for running more resource-demanding applications. To bridge this gap, one solution is to leverage powerful resources residing at remote sites by performing computation offloading. Unfortunately, the state-of-the-art offloading frameworks cannot be applied in many embedded systems supporting applications with soft real-time (SRT) constraints or high delay sensitivity, as they typically optimize response times on a \"best-effort\" basis using heuristics. This paper establishes a soft real-time offloading framework that optimizes the resource utilization of the embedded system while analytically guaranteeing SRT schedulability. The key idea behind the proposed framework is to view offloading-induced delays as suspensions occurring at the local embedded system side, which allows a task being offloaded to be modelled as a suspending task and thus existing SRT suspension-aware scheduling and analysis techniques to be leveraged. Based on this idea, we propose an offloading algorithm, namely Real-time Offloading Decision-making Algorithm (RODA), to make offloading decisions such that SRT schedulability of the task system can be ensured. The optimality properties of RODA have been proved on both uniprocessors and multiprocessors. We conducted extensive simulations on evaluating schedulability and implemented a case study offloading system on top of real hardware to test runtime response time performance. Results demonstrated that RODA is superior to existing performance-driven offloading algorithms, particularly under heavy workloads.","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133840382","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: 3

Response-Time Analysis of Conditional DAG Tasks in Multiprocessor Systems 多处理器系统中条件DAG任务的响应时间分析

2015 27th Euromicro Conference on Real-Time Systems Pub Date : 2015-07-08 DOI: 10.1109/ECRTS.2015.26

Alessandra Melani, M. Bertogna, V. Bonifaci, A. Marchetti-Spaccamela, G. Buttazzo

{"title":"Response-Time Analysis of Conditional DAG Tasks in Multiprocessor Systems","authors":"Alessandra Melani, M. Bertogna, V. Bonifaci, A. Marchetti-Spaccamela, G. Buttazzo","doi":"10.1109/ECRTS.2015.26","DOIUrl":"https://doi.org/10.1109/ECRTS.2015.26","url":null,"abstract":"Different task models have been proposed to represent the parallel structure of real-time tasks executing on manycore platforms: fork/join, synchronous parallel, DAG-based, etc. Despite different schedulability tests and resource augmentation bounds are available for these task systems, we experience difficulties in applying such results to real application scenarios, where the execution flow of parallel tasks is characterized by multiple (and nested) conditional structures. When a conditional branch drives the number and size of sub-jobs to spawn, it is hard to decide which execution path to select for modeling the worst-case scenario. To circumvent this problem, we integrate control flow information in the task model, considering conditional parallel tasks (cp-tasks) represented by DAGs composed of both precedence and conditional edges. For this task model, we identify meaningful parameters that characterize the schedulability of the system, and derive efficient algorithms to compute them. A response time analysis based on these parameters is then presented for different scheduling policies. A set of simulations shows that the proposed approach allows efficiently checking the schedulability of the addressed systems, and that it significantly tightens the schedulability analysis of non-conditional (e.g., Classic DAG) tasks over existing approaches.","PeriodicalId":243434,"journal":{"name":"2015 27th Euromicro Conference on Real-Time Systems","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131264348","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: 127