J. Gustafsson, Andreas Ermedahl, C. Sandberg, B. Lisper
{"title":"Automatic Derivation of Loop Bounds and Infeasible Paths for WCET Analysis Using Abstract Execution","authors":"J. Gustafsson, Andreas Ermedahl, C. Sandberg, B. Lisper","doi":"10.1109/RTSS.2006.12","DOIUrl":"https://doi.org/10.1109/RTSS.2006.12","url":null,"abstract":"Static worst-case execution time (WCET) analysis is a technique to derive upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component for statically deriving safe and tight WCET bounds is information on the possible program flow through the program. Such flow information can be provided manually by user annotations, or automatically by a flow analysis. To make WCET analysis as simple and safe as possible, it should preferably be automatically derived, with no or very limited user interaction. In this paper we present a method for deriving such flow information called abstract execution. This method can automatically calculate loop bounds, bounds for including nested loops, as well as many types of infeasible paths. Our evaluations show that it can calculate WCET estimates automatically, without any user annotations, for a range of benchmark programs, and that our techniques for nested loops and infeasible paths sometimes can give substantially better WCET estimates than using loop bounds analysis only","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"24 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120905214","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":"Diverse Soft Real-Time Processing in an Integrated System","authors":"Caixue Lin, T. Kaldewey, A. Povzner, S. Brandt","doi":"10.1109/RTSS.2006.21","DOIUrl":"https://doi.org/10.1109/RTSS.2006.21","url":null,"abstract":"The simple notion of soft real-time processing has fractured into a spectrum of diverse soft real-time types with a variety of different resource and time constraints. Schedulers have been developed for each of these types, but these are essentially point solutions in the space of soft real-time and no detailed unified definition of soft real-time has previously been provided that includes all types of soft realtime processing. We present a complete real-time taxonomy covering the spectrum of processes from best-effort to hard real-time. The taxonomy divides processes into nine classes based on their resource and timeliness requirements and includes four soft real-time classes, each of which captures a group of soft real-time applications with similar characteristics. We exploit the different features of each of the soft real-time classes to integrate all of them into a single scheduler together with hard real-time and best-effort processes and present results demonstrating their performance","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125335749","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":"Generalized Elastic Scheduling","authors":"Thidapat Chantem, X. Hu, M. Lemmon","doi":"10.1109/RTSS.2006.24","DOIUrl":"https://doi.org/10.1109/RTSS.2006.24","url":null,"abstract":"The elastic task model (Buttazzo et al., 2002) is a powerful model for adapting real-time systems in the presence of uncertainty. This paper generalizes the existing elastic scheduling approach in several directions. It reveals that the original task compression algorithm in (Buttazzo et al., 2002) in fact solves a quadratic programming problem that seeks to minimize the sum of the squared deviation of a task's utilization from initial desired utilization. This finding indicates that the task compression algorithm may be applied to efficiently solve other similar types of problems. In particular, an iterative approach is proposed to solve the task compression problem for real-time tasks with deadlines less than respective periods. Furthermore, a new objective for minimizing the average difference of task periods from desired values is introduced and a closed-form formula is derived for solving the problem without recursion","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122207170","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}
Ravi Kokku, Upendra Shevade, Nishit Shah, A. Mahimkar, Taewon Cho, H. Vin
{"title":"Processor Scheduler for Multi-Service Routers","authors":"Ravi Kokku, Upendra Shevade, Nishit Shah, A. Mahimkar, Taewon Cho, H. Vin","doi":"10.1109/RTSS.2006.38","DOIUrl":"https://doi.org/10.1109/RTSS.2006.38","url":null,"abstract":"In this paper, we describe the design and evaluation of a scheduler (referred to as Everest) for allocating processors to services in high performance, multi-service routers. A scheduler for such routers is required to maximize the number of packets processed within a given delay tolerance, while isolating the performance of services from each other. The design of such a scheduler is novel and challenging because of three domain-specific characteristics: (1) difficult-to-predict and high packet arrival rates, (2) small delay tolerances of packets, and (3) significant overheads for switching allocation of processors from one service to another. These characteristics require that the scheduler be agile and wary simultaneously. Whereas agility enables the scheduler to react quickly to fluctuations in packet arrival rates, wariness prevents the scheduler from wasting computational resources in unnecessary context switches. We demonstrate that by balancing agility and wariness, Everest, as compared to conventional schedulers, reduces by more than an order of magnitude the average delay and the percentage of packets that experience delays greater than their tolerance. We describe a prototype implementation of Everest on Intel's IXP2400 network processor","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130946614","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":"Hard Real-Time Hybrid Garbage Collection with Low Memory Requirements","authors":"Yang Chang, A. Wellings","doi":"10.1109/RTSS.2006.25","DOIUrl":"https://doi.org/10.1109/RTSS.2006.25","url":null,"abstract":"Real-time garbage collection algorithms are usually criticised for their high memory requirements. Even when consuming nearly 50% of CPU time, some garbage collectors ask for at least twice the memory as really needed. This paper explores the fundamental reason for this problem and proposes a new performance indicator for the evaluation of real-time garbage collection algorithms. Use of this performance indicator motivates an algorithm that combines both reference counting and mark-and-sweep techniques. In the presence of our collector, a garbage collected hard real-time system can achieve the correct balance of time-space tradeoff with less effort. In order to provide both temporal and spatial guarantees needed by a hard real-time application, an offline analysis is developed and integrated into the response time analysis framework. Moreover, the use of dual priority scheduling of the garbage collection tasks allows spare capacity in the system to be reclaimed whilst guaranteeing deadlines","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133150479","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":"Real-Time Traffic Management in Sensor Networks","authors":"K. Karenos, V. Kalogeraki","doi":"10.1109/RTSS.2006.40","DOIUrl":"https://doi.org/10.1109/RTSS.2006.40","url":null,"abstract":"In this work we propose a traffic management mechanism to support real-time flows in highly unpredictable sensor network environments. The mechanism is based on a joint traffic regulation and end-to-end scheduling approach; a traffic regulation component adjusts the incoming packet rate to implicitly control the channel load and intelligently rejects packets that are more likely to miss their deadline while a laxity-based scheduling component projects the packets' per-hop delay and compensates for network end-to-end delays. Thus, high success ratios without severely degrading the fidelity are achieved. Our mechanism attempts to maintain accuracy in a resource-efficient manner even under extremely unstable network conditions where delays are difficult to model and compute. Furthermore, the adoption of a component-based approach allows for substantial independence from both the MAC and routing layers. We thoroughly evaluate our mechanism and demonstrate its accuracy and performance merits","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126955330","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. Mangharam, Anthony G. Rowe, R. Rajkumar, R. Suzuki
{"title":"Voice over Sensor Networks","authors":"R. Mangharam, Anthony G. Rowe, R. Rajkumar, R. Suzuki","doi":"10.1109/RTSS.2006.51","DOIUrl":"https://doi.org/10.1109/RTSS.2006.51","url":null,"abstract":"Wireless sensor networks have traditionally focused on low duty-cycle applications where sensor data are reported periodically in the order of seconds or even longer. This is due to typically slow changes in physical variables, the need to keep node costs low and the goal of extending battery lifetime. However, there is a growing need to support real-time streaming of audio and/or low-rate video even in wireless sensor networks for use in emergency situations and short-term intruder detection. In this paper, we present FireFly, a time-synchronized sensor network platform for real-time data streaming across multiple hops. FireFly is composed of several integrated layers including specialized low-cost hardware, a sensor network operating system, a real-time link layer and network scheduling which together provide efficient support for applications with timing constraints. In order to achieve high end-to-end throughput, bounded latency and predictable lifetime, we employ hardware-based time synchronization. Multiple tasks including audio sampling, networking and sensor reading are scheduled using the nano-RK RTOS. We have implemented RT-Link, a TDMA-based link layer protocol for message exchange on well-defined time slots and pipelining along multiple hops. We use this platform to support 2-way audio streaming concurrently with sensing tasks. For interactive voice, we investigate TDMA-based slot scheduling with balanced bi-directional latency while meeting audio timeliness requirements. Finally, we describe our experimental deployment of 42 nodes in a coal mine, and present measurements of the end-to-end throughput, jitter, packet loss and voice quality","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127878452","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}
P. Tsai, H. Yeh, C. Y. Yu, P. Hsiu, C. Shih, J. W. Liu
{"title":"Compliance Enforcement of Temporal and Dosage Constraints","authors":"P. Tsai, H. Yeh, C. Y. Yu, P. Hsiu, C. Shih, J. W. Liu","doi":"10.1109/RTSS.2006.14","DOIUrl":"https://doi.org/10.1109/RTSS.2006.14","url":null,"abstract":"Medication dispensers treated in this paper are designed to help improve compliance by users who live at homes and take medications over long periods of time. The paper first presents an overview of medication specifications that define constraints for dispensers and dispenser components that administer medications as specified. When given a specification and constraints defined by it, the dispenser scheduler checks for consistency and feasibility of constraints and schedules medications to meet the constraints. Several basic algorithms needed for these purposes are described and evaluated","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125601699","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 Necessary and Sometimes Sufficient Condition for the Feasibility of Sets of Sporadic Hard-Deadline Tasks","authors":"T. Baker, M. Cirinei","doi":"10.1109/RTSS.2006.7","DOIUrl":"https://doi.org/10.1109/RTSS.2006.7","url":null,"abstract":"This paper describes a necessary condition for feasibility of scheduling a set of sporadic hard-deadline tasks on identical multiprocessor platforms, which is also a sufficient condition if there is only a single processor. The key contribution is the characterization of the maximum, over all time intervals of a given length, of the amount of computation that must be completed to meet all deadlines, and a method of computing this function efficiently to any desired degree of accuracy. Empirical data are provided to verify that the new infeasibility test can be computed efficiently and is an improvement over previously known checks for infeasibility","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127086643","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}
Tanya L. Crenshaw, C. Robinson, Hui Ding, P. Kumar, L. Sha
{"title":"A Pattern for Adaptive Behavior in Safety-Critical, Real-Time Middleware","authors":"Tanya L. Crenshaw, C. Robinson, Hui Ding, P. Kumar, L. Sha","doi":"10.1109/RTSS.2006.8","DOIUrl":"https://doi.org/10.1109/RTSS.2006.8","url":null,"abstract":"Patterns are a valuable method for communicating software engineering expertise about proven solutions for common problems. This paper evaluates the use of domain-independent patterns in a case study of Etherware, a middleware for networked control with a real-time, safety-critical applications model. The case study illustrates the positive and negative impact that four existing patterns have on availability, reliability, and robustness for real-time, safety-critical systems. In particular, we observe Etherware's specialized usage of the filter pattern, confirm this usage among other middleware technologies, and subsequently present the adaptive control filter, a design pattern for real-time, safety-critical middleware which can mitigate timing dependencies in networked control","PeriodicalId":353932,"journal":{"name":"2006 27th IEEE International Real-Time Systems Symposium (RTSS'06)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114217317","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}