{"title":"Combining Abstract Interpretation with Model Checking for Timing Analysis of Multicore Software","authors":"Mingsong Lv, W. Yi, Nan Guan, Ge Yu","doi":"10.1109/RTSS.2010.30","DOIUrl":"https://doi.org/10.1109/RTSS.2010.30","url":null,"abstract":"It is predicted that multicores will be increasingly used in future embedded real-time systems for high performance and low energy consumption. The major obstacle is that we may not predict and provide any guarantee on real-time properties of software on such platforms. The shared memory bus is among the most critical resources, which severely degrade the timing predictability of multicore software due to the access contention between cores. In this paper, we study a multicore architecture where each core has a local L1 cache and all cores use a shared bus to access the off-chip memory. We use Abstract Interpretation (AI) to analyze the local cache behavior of a program running on a dedicated core. Based on the cache analysis, we construct a Timed Automaton (TA) to model when the programs access the memory bus. Then we model the shared bus also using timed automata. The TA models for the bus and programs will be explored using the UPPAAL model checker to find the WECTs for the respective programs. Based on the presented techniques, we have developed a tool for multicore timing analysis, which allows automatic generation of the TA models from binary code and WCET estimation for any given TA model of the shared bus. Extensive experiments have been conducted, showing that the combined approach can significantly tighten the estimations. As examples, we have studied the TDMA and FCFS buses, of which the WCET bounds can be tightened by up to 240% and 82% respectively, compared with the worst-case bounds estimated based on worst-case bus access delay.","PeriodicalId":202891,"journal":{"name":"2010 31st IEEE Real-Time Systems Symposium","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130926719","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 More Precise Abstract Domain for Multi-level Caches for Tighter WCET Analysis","authors":"Tyler Sondag, Hridesh Rajan","doi":"10.1109/RTSS.2010.8","DOIUrl":"https://doi.org/10.1109/RTSS.2010.8","url":null,"abstract":"As demand for computational power of embedded applications has increased, their architectures have become more complex. One result of this increased complexity are real-time embedded systems with set-associative multi-level caches. Multi-level caches complicate the process of program analysis techniques such as worst case execution time (WCET). To address this need we have developed a sound cache behavior analysis that handles multi-level instruction and data caches. Our technique relies on a new abstraction, live caches, which models relationships between cache levels to improve accuracy. Our analysis improves upon previous multi-level cache analysis in three ways. First, it handles write-back, a common feature of cache models, soundly. Second, it handles both instruction and data cache hierarchies, and third, it improves precision of cache analysis. For standard WCET benchmarks and a multi-level cache configuration analyzed by previous work, we observed that live caches improve WCET precision resulting in an average of 6.3% reduction in computed WCET.","PeriodicalId":202891,"journal":{"name":"2010 31st IEEE Real-Time Systems Symposium","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134417585","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}
R. Tan, G. Xing, Zhaohui Yuan, Xue Liu, Jianguo Yao
{"title":"System-Level Calibration for Fusion-Based Wireless Sensor Networks","authors":"R. Tan, G. Xing, Zhaohui Yuan, Xue Liu, Jianguo Yao","doi":"10.1109/RTSS.2010.29","DOIUrl":"https://doi.org/10.1109/RTSS.2010.29","url":null,"abstract":"Wireless sensor networks are typically composed of low-cost sensors that are deeply integrated in physical environments. As a result, the sensing performance of a wireless sensor network is inevitably undermined by biases in imperfect sensor hardware and the noises in data measurements. Although a variety of calibration methods have been proposed to address these issues, they often adopt the device-level approach that becomes intractable for moderate- to large-scale networks. In this paper, we propose a two-tier system-level calibration approach for a class of sensor networks that employ data fusion to improve the sensing performance. In the first tier of our calibration approach, each sensor learns its local sensing model from noisy measurements using an online algorithm and only transmits a few model parameters. In the second tier, sensors' local sensing models are then calibrated to a common system sensing model. Our approach fairly distributes computation overhead among sensors and significantly reduces the communication overhead of calibration. Based on this approach, we develop an optimal model calibration scheme that maximizes the target detection probability of a sensor network under bounded false alarm rate. Our approach is evaluated by both experiments on a testbed of TelosB motes and extensive simulations based on data traces collected in a real vehicle detection experiment. The results demonstrate that our system-level calibration approach can significantly boost the detection performance of sensor networks in the scenarios with low signal-to-noise ratios.","PeriodicalId":202891,"journal":{"name":"2010 31st IEEE Real-Time Systems Symposium","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115274944","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}
Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen
{"title":"Real-Time Scheduling for WirelessHART Networks","authors":"Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen","doi":"10.1109/RTSS.2010.41","DOIUrl":"https://doi.org/10.1109/RTSS.2010.41","url":null,"abstract":"WirelessHART is an open wireless sensor-actuator network standard for industrial process monitoring and control that requires real-time data communication between sensor and actuator devices. Salient features of a WirelessHART network include a centralized network management architecture, multi-channel TDMA transmission, redundant routes, and avoidance of spatial reuse of channels for enhanced reliability and real-time performance. This paper makes several key contributions to real-time transmission scheduling in WirelessHART networks: (1) formulation of the end-to-end real-time transmission scheduling problem based on the characteristics of WirelessHART, (2) proof of NP-hardness of the problem, (3) an optimal branch-and-bound scheduling algorithm based on a necessary condition for schedulability, and (4) an efficient and practical heuristic-based scheduling algorithm called Conflict-aware Least Laxity First (C-LLF). Extensive simulations based on both random topologies and real network topologies of a physical testbed demonstrate that C-LLF is highly effective in meeting end-to-end deadlines in WirelessHART networks, and significantly outperforms common real-time scheduling policies.","PeriodicalId":202891,"journal":{"name":"2010 31st IEEE Real-Time Systems Symposium","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128076944","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":"An Algorithm for Scheduling Certifiable Mixed-Criticality Sporadic Task Systems","authors":"Haohan Li, Sanjoy Baruah","doi":"10.1109/RTSS.2010.18","DOIUrl":"https://doi.org/10.1109/RTSS.2010.18","url":null,"abstract":"Many safety-critical embedded systems are subject to certification requirements. However, only a subset of the functionality of the system may be safety-critical and hence subject to certification, the rest of the functionality is non safety-critical and does not need to be certified. Certification requirements in such \"mixed-criticality\" systems give rise to some interesting scheduling problems, that cannot be satisfactorily addressed using techniques from conventional scheduling theory. In prior work, we have studied the scheduling and analysis of mixed criticality systems that are specified as finite collections of jobs executing on a single shared preemptive processor. In this paper, we consider mixed criticality systems that are comprised of finite collections of recurrent tasks, specified using a mixed-criticality generalization of the widely-used sporadic tasks model. We design a priority-based algorithm for scheduling such systems, derive an algorithm for computing priorities, and obtain a sufficient schedulability condition for efficiently determining whether a given mixed-criticality system can be successfully scheduled by this algorithm.","PeriodicalId":202891,"journal":{"name":"2010 31st IEEE Real-Time Systems Symposium","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134271083","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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