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A PTAS for assigning sporadic tasks on two-type heterogeneous multiprocessors
Raravi, Gurulingesh; Nélis, VincentConsider the problem of determining a task-toprocessor assignment for a given collection of implicit-deadline sporadic tasks upon a multiprocessor platform in which there are two distinct kinds of processors. We propose a polynomialtime approximation scheme (PTAS) for this problem. It offers the following guarantee: for a given task set and a given platform, if there exists a feasible task-to-processor assignme...
Task assignment algorithms for two-type heterogeneous multiprocessors
Raravi, Gurulingesh; Andersson, Björn; Bletsas, Konstantinos; Nélis, VincentConsider the problem of assigning real-time tasks on a heterogeneous multiprocessor platform comprising two different types of processors — such a platform is referred to as two-type platform. We present two linearithmic timecomplexity algorithms, SA and SA-P, each providing the follow- ing guarantee. For a given two-type platform and a given task set, if there exists a feasible task-to-processor-type assignmen...
Preemption delay analysis for floating non-preemptive region scheduling
Marinho, José; Nélis, Vincent; Petters, Stefan M.; Puaut, IsabelleIn real-time systems, there are two distinct trends for scheduling task sets on unicore systems: non-preemptive and preemptive scheduling. Non-preemptive scheduling is obviously not subject to any preemption delay but its schedulability may be quite poor, whereas fully preemptive scheduling is subject to preemption delay, but benefits from a higher flexibility in the scheduling decisions. The time-delay involve...
An improved preemption delay upper bound for floating non-preemptive region
Marinho, José; Nélis, Vincent; Petters, Stefan M.; Puaut, IsabelleIn embedded systems, the timing behaviour of the control mechanisms are sometimes of critical importance for the operational safety. These high criticality systems require strict compliance with the offline predicted task execution time. The execution of a task when subject to preemption may vary significantly in comparison to its non-preemptive execution. Hence, when preemptive scheduling is required to operat...
Real-time scheduling with resource sharing on uniform multiprocessors
Raravi, Gurulingesh; Nélis, Vincent; Andersson, BjörnConsider the problem of scheduling a set of implicit-deadline sporadic tasks to meet all deadlines on a uniform multiprocessor platform where each task may access at most one of ; R; shared resources and at most once by each job of that task. The resources have to be accessed in a mutually exclusive manner. We propose an algorithm, GIS-vpr, which offers the guarantee that if a task set is schedulable to meet d...
An analysis of the impact of bus contention on the WCET in multicores
Dasari, Dakshina; Nélis, VincentThe use of multicores is becoming widespread inthe field of embedded systems, many of which have real-time requirements. Hence, ensuring that real-time applications meet their timing constraints is a pre-requisite before deploying them on these systems. This necessitates the consideration of the impact of the contention due to shared lowlevel hardware resources like the front-side bus (FSB) on the Worst-CaseExe...
WCET analysis considering contention on memory bus in COTS-based multicores
Dasari, Dakshina; Nélis, Vincent; Andersson, BjörnThe usage of COTS-based multicores is becoming widespread in the field of embedded systems. Providing realtime guarantees at design-time is a pre-requisite to deploy real-time systems on these multicores. This necessitates the consideration of the impact of the contention due to shared low-level hardware resources on the Worst-Case Execution Time (WCET) of the tasks. As a step towards this aim, this paper first...
Partitioned scheduling of multimode systems on multiprocessor platforms: when t...
Marinho, José; Raravi, Gurulingesh; Nélis, Vincent; Petters, Stefan M.Systems composed of distinct operational modes are a common necessity for embedded applications with strict timing requirements. With the emergence of multi-core platforms protocols to handle these systems are required in order to provide this basic functionality.In this work a description on the problems of creating an effective mode-transition protocol are presented and it is proven that in some cases previou...
Global-EDF scheduling of multimode real- time systems considering mode independ...
Nélis, Vincent; Andersson, Björn; Marinho, José; Petters, Stefan M.Embedded real-time systems often have to support the embedding system in very different and changing application scenarios. An aircraft taxiing, taking off and in cruise flight is one example. The different application scenarios are reflected in the software structure with a changing task set and thus different operational modes. At the same time there is a strong push for integrating previously isolated functi...
A tighter analysis of the worst-case endto- end communication delay in massive ...
Nélis, Vincent; Dasari, Dakshina; Nikolic, Borislav; Petters, Stefan M."Many-core” systems based on the Network-on- Chip (NoC) architecture have brought into the fore-front various opportunities and challenges for the deployment of real-time systems. Such real-time systems need timing guarantees to be fulfilled. Therefore, calculating upper-bounds on the end-to-end communication delay between system components is of primary interest. In this work, we identify the limitations of an...
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