{"title":"A Fully Preemptive Multiprocessor Semaphore Protocol for Latency-Sensitive Real-Time Applications","authors":"Björn B. Brandenburg","doi":"10.1109/ECRTS.2013.38","DOIUrl":"https://doi.org/10.1109/ECRTS.2013.38","url":null,"abstract":"Independence preservation, a property in real-time locking protocols that isolates latency-sensitive tasks from delays due to unrelated critical sections, is identified, formalized, and studied in detail. The key to independence preservation is to ensure that tasks remain fully preemptive at all times. For example, on uniprocessors, the classic priority inheritance protocol is independence-preserving. It is shown that, on multiprocessors, independence preservation is impossible if job migrations are disallowed. The O(m) independence-preserving protocol (OMIP), a new, asymptotically optimal binary sempahore protocol based on migratory priority inheritance, is proposed and analyzed. The OMIP is the first independence-preserving, real-time, suspension-based locking protocol for clustered job-level fixed-priority scheduling. It is shown to benefit latency-sensitive workloads, both analytically by means of schedulability experiments, and empirically using response-time measurements in LITMUSRT.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124850793","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}
Bryan C. Ward, Jonathan L. Herman, C. Kenna, James H. Anderson
{"title":"Outstanding Paper Award: Making Shared Caches More Predictable on Multicore Platforms","authors":"Bryan C. Ward, Jonathan L. Herman, C. Kenna, James H. Anderson","doi":"10.1109/ECRTS.2013.26","DOIUrl":"https://doi.org/10.1109/ECRTS.2013.26","url":null,"abstract":"In safety-critical cyber-physical systems, the usage of multicore platforms has been hampered by problems due to interactions across cores through shared hardware. The inability to precisely characterize such interactions can lead to worst-case execution time pessimism that is so great, the extra processing capacity of additional cores is entirely negated. In this paper, several techniques are proposed and analyzed for dealing with such interactions in the context of shared caches. These techniques are applied in a mixed-criticality scheduling framework motivated by the needs of next-generation unmanned air vehicles.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132301586","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":"Suspension-Aware Analysis for Hard Real-Time Multiprocessor Scheduling","authors":"Cong Liu, James H. Anderson","doi":"10.1109/ECRTS.2013.36","DOIUrl":"https://doi.org/10.1109/ECRTS.2013.36","url":null,"abstract":"In many real-time systems, tasks may experience suspension delays when accessing external devices. The problem of analyzing task systems with such suspensions on multiprocessors has been relatively unexplored. The commonly used suspension-oblivious approach of treating all suspensions as computation can be quite pessimistic. As an alternative, this paper presents the first suspension-aware hard real-time multiprocessor schedulability analysis for task systems with suspensions, under both global fixed-priority and global EDF scheduling. In experiments presented herein, the proposed schedulability tests proved to be superior to suspension-oblivious tests. Moreover, when applied to ordinary arbitrary-deadline sporadic task systems with no suspensions, the proposed analysis for fixed-priority scheduling improves upon prior analysis.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121865115","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":"Mixed Critical Earliest Deadline First","authors":"Dario Socci, P. Poplavko, S. Bensalem, M. Bozga","doi":"10.1109/ECRTS.2013.20","DOIUrl":"https://doi.org/10.1109/ECRTS.2013.20","url":null,"abstract":"Using the advances of the modern microelectronics technology, the safety-critical systems, such as avionics, can reduce their costs by integrating multiple tasks on one device. This makes such systems essentially mixed-critical, as this brings together different tasks whose safety assurance requirements may differ significantly. In the context of mixed-critical scheduling theory, we studied the dual criticality problem of scheduling a finite set of hard real-time jobs. In this work we propose an algorithm which is proved to dominate OCBP, a state-of-the art algorithm for this problem that is optimal over fixed job priority algorithms. We show through empirical studies that our algorithm can reduce the set of non-schedulable instances by a factor of two or, under certain assumptions, by a factor of four, when compared to OCBP.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133431771","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}
Bogdan Tanasa, Unmesh D. Bordoloi, P. Eles, Zebo Peng
{"title":"Probabilistic Timing Analysis for the Dynamic Segment of FlexRay","authors":"Bogdan Tanasa, Unmesh D. Bordoloi, P. Eles, Zebo Peng","doi":"10.1145/2870635","DOIUrl":"https://doi.org/10.1145/2870635","url":null,"abstract":"We propose an analytical framework for probabilistic timing analysis of the event-triggered Dynamic segment of the Flex Ray communication protocol. Specifically, our framework computes the Deadline Miss Ratios of each message. The core problem is formulated as a Mixed Integer Linear Program (MILP). Given the intractability of the problem, we also propose several techniques that help to mitigate the running times of our tool. This includes the re-engineering of the problem to run it on GPUs as well as re-formulating the MILP itself.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133338520","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}
A. Gujarati, Felipe Cerqueira, Björn B. Brandenburg
{"title":"Outstanding Paper Award: Schedulability Analysis of the Linux Push and Pull Scheduler with Arbitrary Processor Affinities","authors":"A. Gujarati, Felipe Cerqueira, Björn B. Brandenburg","doi":"10.1109/ECRTS.2013.18","DOIUrl":"https://doi.org/10.1109/ECRTS.2013.18","url":null,"abstract":"Contemporary multiprocessor real-time operating systems, such as VxWorks, LynxOS, QNX, and real-time variants of Linux, allow a process to have an arbitrary processor affinity, that is, a process may be pinned to an arbitrary subset of the processors in the system. Placing such a hard constraint on process migrations can help to improve cache performance of specific multi-threaded applications, achieve isolation among components, and aid in load-balancing. However, to date, the lack of schedulability analysis for such systems prevents the use of arbitrary processor affinities in predictable hard real-time applications. In this paper, it is shown that job-level fixed-priority scheduling with arbitrary processor affinities is strictly more general than global, clustered, and partitioned job-level fixed-priority scheduling. The Linux push and pull scheduler is studied as a reference implementation and techniques for the schedulability analysis of hard real-time tasks with arbitrary processor affinity masks are presented. The proposed tests work by reducing the scheduling problem to ``global-like'' sub-problems to which existing global schedulability tests can be applied. Schedulability experiments show the proposed techniques to be effective.","PeriodicalId":247550,"journal":{"name":"2013 25th Euromicro Conference on Real-Time Systems","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127227852","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}