2017 IEEE Real-Time Systems Symposium (RTSS)最新文献

{"title":"Integrated Analysis of Cache Related Preemption Delays and Cache Persistence Reload Overheads","authors":"Syed Aftab Rashid, Geoffrey Nelissen, S. Altmeyer, Robert I. Davis, E. Tovar","doi":"10.1109/RTSS.2017.00025","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00025","url":null,"abstract":"Schedulability analysis for tasks running on micro- processors with cache memory is incomplete without a treatment of Cache Related Preemption Delays (CRPD) and Cache Persistence Reload Overheads (CPRO). State-of-the-art analyses compute CRPD and CPRO independently, which might result in counting the same overhead more than once. In this paper, we analyze the pessimism associated with the independent calculation of CRPD and CPRO in comparison to an integrated approach. We answer two main questions: (1) Is it benecial to integrate the calculation of CRPD and CPRO? (2) When and to what extent can we gain in terms of schedulability by integrating the calculation of CRPD and CPRO? To achieve this, we (i) identify situations where considering CRPD and CPRO separately might result in overestimating the total memory overhead suffered by tasks, (ii) derive new analyses that integrate the calculation of CRPD and CPRO; and (iii) perform a thorough experimental evaluation using benchmarks to compare the performance of the integrated analysis against the separate calculation of CRPD and CPRO.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128828454","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":"Work-in-Progress: Toward a Coq-Certified Tool for the Schedulability Analysis of Tasks with Offsets","authors":"Xiaojie Guo, Sophie Quinton, Pascal Fradet, J. Monin","doi":"10.1109/RTSS.2017.00049","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00049","url":null,"abstract":"This paper presents the first steps toward a formally proven tool for schedulability analysis of tasks with offsets. We formalize and verify the seminal response time analysis of Tindell by extending the Prosa proof library, which is based on the Coq proof assistant. Thanks to Coq’s extraction capabilities, this will allow us to easily obtain a certified analyzer. Additionally, we want to build a Coq certifier that can verify the correctness of results obtained using related (but uncertified), already existing analyzers. Our objective is to investigate the advantages and drawbacks of both approaches, namely the certified analysis and the certifier. The work described in this paper as well as its continuation is intended to enrich the Prosa library.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122011328","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":"Beyond Implicit-Deadline Optimality: A Multiprocessor Scheduling Framework for Constrained-Deadline Tasks","authors":"Hyeongboo Baek, H. Chwa, Jinkyu Lee","doi":"10.1109/RTSS.2017.00038","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00038","url":null,"abstract":"In the real-time systems community, many studies have addressed how to efficiently utilize a multiprocessor platform so as to accommodate as many periodic/sporadic real-time tasks as possible without violating any timing constraints. The scheduling theory has sufficiently matured for a set of implicit-deadline tasks (the relative deadline equal to the period), yielding a class of optimal scheduling algorithms. However, the same does not hold for a set of constrained-deadline tasks (the relative deadline no larger than the period) in that those task sets have been fully covered by neither existing implicit-deadline optimal scheduling algorithms nor heuristic scheduling algorithms., In this paper, we propose a scheduling framework that not only takes advantage of both existing implicit-deadline optimal and heuristic algorithms, but also surpasses both in finding schedulable constrained-deadline task sets. The proposed framework logically divides a given task set into the higher- and lower-priority classes and schedules the classes using an implicit-deadline optimal algorithm and a heuristic algorithm, respectively. Then, while the proposed framework guarantees schedulability of tasks in the higher-priority class by the target implicit-deadline optimal algorithm, we need to address the following technical issues for enabling tasks in the lower-priority class to efficiently reclaim remaining processor capacity while guaranteeing their schedulability: (i) division of a given task set into the two classes, (ii) selection/development of scheduling algorithms for the two classes, and (iii) development of a schedulability test for the framework with given (i) and (ii). We present a general case showing how to address (i)-(iii), and then a specific case addressing how to further improve schedulability by utilizing characteristics of the specific case. Our simulation results demonstrate that the proposed framework outperforms all existing scheduling algorithms in covering schedulable task sets; in particular, if we focus on task sets with the system density larger than the number of processors, the framework finds up to 446.3% additional schedulable task sets, compared to task sets covered by at least one of existing scheduling algorithms.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127507635","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":"Memory Bank Partitioning for Fixed-Priority Tasks in a Multi-core System","authors":"Sheng-Wei Cheng, Jian-Jia Chen, J. Reineke, Tei-Wei Kuo","doi":"10.1109/RTSS.2017.00027","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00027","url":null,"abstract":"In a multi-core platform, resources, such as memory banks and buses, are mostly shared among all cores for power, performance, and cost reasons. The access interference on the shared resources poses a major challenge on the analysis of real-time properties, but can be alleviated if task data partition onto memory banks is applied with care. In this paper, we consider to schedule RAS (resource access sporadic) tasks onto a platform consisting of homogeneous cores and capacity-limited memory banks. According to our observation, we should avoid internal data spreading among the memory banks for a task while advocate external data spreading among memory banks for a given task set. We propose a two-phase algorithm with (4 + ρ + 3(2γ+1)/γ) speedup factor and (γ + 1) memory augmentation factor, where ρ γ 0 and ρ ≥ 1. The derived adjustable resource augmentation factors can be useful in terms of system synthesis and schedulability. Moreover, under the premise that a given task set is feasible, we devise a bi-section approach that can derive a schedulable solution requiring the least amount of memory augmentation. According to our experiment results, the proposed algorithm significantly outperformed the state-of-the-art algorithm [15] in terms of schedulability test even when memory augmentation is prohibited.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126461298","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":"Temporal Capabilities: Access Control for Time","authors":"Phani Kishore Gadepalli, Robert Gifford, Lucas Baier, M. Kelly, Gabriel Parmer","doi":"10.1109/RTSS.2017.00013","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00013","url":null,"abstract":"Embedded systems are increasingly required to handle code of various qualities that must often be isolated, yet predictably share resources. This has motivated the isolation of, for example, mission-critical code from best-effort features using isolation structures such as virtualization. Such systems usually focus on limiting interference between subsystems, which complicates the increasingly common functional dependencies between them. Though isolation must be paramount, the fundamental goal of efficiently sharing hardware motivates a principled mechanism for cooperating between subsystems. This paper introduces Temporal Capabilities (TCaps) which integrate CPU management into a capability-based access-control system and distribute authority for scheduling. In doing so, the controlled temporal coordination between subsystems becomes a first-class concern of the system. By enabling temporal delegations to accompany activations and requests for service, we apply TCaps to a virtualization environment with a shared VM for orchestrating I/O. We show that TCaps, unlike prioritizations and carefully chosen budgets, both meet deadlines for a hard real-time subsystem, and maintain high throughput for a best-effort subsystem.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127236329","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":"Fixed-Priority Schedulability of Sporadic Tasks on Uniprocessors is NP-Hard","authors":"Pontus Ekberg, W. Yi","doi":"10.1109/RTSS.2017.00020","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00020","url":null,"abstract":"We study the computational complexity of the FP-schedulability problem for sporadic or synchronous periodic tasks on a preemptive uniprocessor. We show that this problem is (weakly) NP-hard, even when restricted to either (i) task sets with implicit deadlines and rate-monotonic priority ordering, or (ii) task sets with constrained deadlines, deadline-monotonic priority ordering and utilization bounded by any constant c, such that 0 c 1.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122201179","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":"Work-in-Progress: Isochronous Execution Models for Mixed-Criticality Systems on Parallel Processors","authors":"B. Alahmad, S. Gopalakrishnan","doi":"10.1109/RTSS.2017.00050","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00050","url":null,"abstract":"We propose redundancy-based execution models to address the reliability and correctness of safety/time-critical applications, and in particular, mixed-criticality systems. In our models, every job has one or more (possibly identical) versions, and all versions of a job are to run isochronously on multiple parallel machines in a lockstep fashion. The redundant machines act as monitoring coprocessors, and the execution of a job is deemed successful as soon as one of its versions completes within its worst-case execution time estimate, at which point we may terminate all the other versions. Doing so e ectively increases the chance that a job completes successfully and thus provides timing guarantees in the form of increased predictability. We present several allocation and scheduling problems with varying levels of generality, with the objective of minimizing the maximum makespan across all processors.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133872939","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":"Aerial Video Stream over Multi-hop Using Adaptive TDMA Slots","authors":"L. Pinto, L. Almeida, Hassan Alizadeh, Anthony G. Rowe","doi":"10.1109/RTSS.2017.00022","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00022","url":null,"abstract":"Unmanned Aerial Vehicles (UAVs) are rapidly becoming an important tool for applications like surveillance, target tracking and facility monitoring. In many of these contexts, one or more UAVs need to reach an area of interest (AOI) while streaming live video to a ground station (GS) where one or more operators inspect the AOI and carry out fine control of UAVs position. In remote areas, intermediate UAVs can act as relays and form a line network to extend range. Interactive control requires a live video stream where both throughput and delay are important. In this paper, we show that routing packets over CSMA/CA (native medium access protocol of WiFi, the most common wireless technology among UAVs) behaves poorly in this context due to link asymmetries. We propose a novel distributed, adaptive and self-synchronized TDMA protocol (DVSP) that both enhances delay and packet delivery while operating on commodity hardware and leveraging a standard UDP/IP protocol stack. We prove that DVSP converges to a global solution that minimizes delay using local information, only, thus in a fully distributed manner. Real world experiments with multiple UAVs show gains in delay up to 75%, and packet delivery up to 50%, without sacrificing goodput.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117325049","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":"RT-IFTTT: Real-Time IoT Framework with Trigger Condition-Aware Flexible Polling Intervals","authors":"Seonyeong Heo, Seungbin Song, Jong Kim, Hanjun Kim","doi":"10.1109/RTSS.2017.00032","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00032","url":null,"abstract":"With a simple “If This Then That” syntax, IoT frameworks such as IFTTT and Microsoft Flow allow users to easily create custom applets integrating sensors and actuators. Users expect appropriate actions to be taken within a certain latency in response to sensor value changes while the sensors usually have limited battery power. Therefore, reading the sensor values at the right time point is crucial for the IoT frameworks to support real-time responses of the applets while saving battery lives of sensors. However, existing IoT frameworks periodically read the sensor data with fixed intervals without reflecting current sensor values and trigger conditions of applets, so the intervals are either too long to meet the real-time constraints, or too short wasting batteries of sensors. This work extends the existing IFTTT syntax for users to describe real-time constraints, and proposes the first real-time IoT framework with trigger condition-aware flexible polling intervals, called RT-IFTTT. RT-IFTTT analyzes current sensor values, trigger conditions and constraints of all the applets in the framework, and dynamically calculates the efficient polling intervals for each sensor. This work collects real-world sensing data from 10 physical sensors for 10 days, and shows that the RT-IFTTT framework with the proposed scheduling algorithm executes 100 to 400 applets according to user-defined real-time constraints with up to 64.12% less sensor polling counts compared to the framework with the fixed intervals.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127163728","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":"Global EDF-Based Scheduling of Multiple Independent Synchronous Dataflow Graphs","authors":"Abhishek Singh, Sanjoy Baruah","doi":"10.1109/RTSS.2017.00036","DOIUrl":"https://doi.org/10.1109/RTSS.2017.00036","url":null,"abstract":"The global scheduling of systems that can be modeled as collections of multiple independent recurrent real-time tasks, each represented as a synchronous dataflow graph (SDFG), upon an identical multiprocessor platform is considered. An EDF-based scheduling algorithm is proved optimal under the speedup factor metric, and a speedup-optimal sufficient schedulability test is derived.","PeriodicalId":407932,"journal":{"name":"2017 IEEE Real-Time Systems Symposium (RTSS)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128207802","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}