Browsing by Author "Indrusiak, Leandro"
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- An extensible framework for multicore response time analysisPublication . Davis, Robert; Altmeyer, Sebastian; Indrusiak, Leandro; Maiza, Claire; Nélis, Vincent; Reineke, JanIn this paper, we introduce a multicore response time analysis (MRTA) framework, which decouples response time analysis from a reliance on context-independent WCET values. Instead, the analysis formulates response times directly from the demands placed on different hardware resources. The MRTA framework is extensible to different multicore architectures, with a variety of arbitration policies for the common interconnects, and different types and arrangements of local memory. We instantiate the framework for single level local data and instruction memories (cache or scratchpads), for a variety of memory bus arbitration policies, including: Round-Robin, FIFO, Fixed-Priority, Processor-Priority, and TDMA, and account for DRAM refreshes. The MRTA framework provides a general approach to timing verification for multicore systems that is parametric in the hardware configuration and so can be used at the architectural design stage to compare the guaranteed levels of real-time performance that can be obtained with different hardware configurations. We use the framework in this way to evaluate the performance of multicore systems with a variety of different architectural components and policies. These results are then used to compose a predictable architecture, which is compared against a reference architecture designed for good average-case behaviour. This comparison shows that the predictable architecture has substantially better guaranteed real-time performance, with the precision of the analysis verified using cycle-accurate simulation.
- Buffer-aware bounds to multi-point progressive blocking in priority-preemptive NoCsPublication . Indrusiak, Leandro; Burns, Alan; Nikolic, BorislavThis paper aims to reduce the pessimism of the analysis of the multi-point progressive blocking (MPB) problem in real-time priority-preemptive wormhole networks-on-chip. It shows that the amount of buffering on each network node can influence the worst-case interference that packets can suffer along their routes, and it proposes a novel analytical model that can quantify such interference as a function of the buffer size. It shows that, perhaps counter-intuitively, smaller buffers can result in lower upper-bounds on interference and thus improved schedulability. Didactic examples and large-scale experiments provide evidence of the strength of the proposed approach.
- A Generic and Compositional Framework for Multicore Response Time AnalysisPublication . Altmeyer, Sebastian; Davis, Robert; Indrusiak, Leandro; Maiza, Claire; Nélis, Vincent; Reineke, JanIn this paper, we introduce a Multicore Response Time Analysis (MRTA) framework. This framework is extensible to different multicore architectures, with various types and arrangements of local memory, and different arbitration policies for the common interconnects. We instantiate the framework for single level local data and instruction memories (cache or scratchpads), for a variety of memory bus arbitration policies, including: Round-Robin, FIFO, Fixed-Priority, Processor-Priority, and TDMA, and account for DRAM refreshes. The MRTA framework provides a general approach to timing verification for multicore systems that is parametric in the hardware configuration and so can be used at the architectural design stage to compare the guaranteed levels of performance that can be obtained with different hardware configurations. The MRTA framework decouples response time analysis from a reliance on context independent WCET values. Instead, the analysis formulates response times directly from the demands on different hardware resources.
- Networked embedded systems for active flow control in aircraftPublication . Tovar, Eduardo; Pereira, Nuno; Bate, Iain; Indrusiak, Leandro; Penna, Sérgio; Negrão, José; Viana, Júlio C.; Philipp, François; Mayer, Dirk; Heras, José; Pacheco, Filipe; Loureiro, JoãoAerodynamic drag is known to be one of the factors contributing more to increased aircraft fuel consumption. The primary source of skin friction drag during flight is the boundary layer separation. This is the layer of air moving smoothly in the immediate vicinity of the aircraft. In this paper we discuss a cyber-physical system approach able of performing an efficient suppression of the turbulent flow by using a dense sensing deployment to detect the low pressure region and a similarly dense deployment of actuators to manage the turbulent flow. With this concept, only the actuators in the vicinity of a separation layer are activated, minimizing power consumption and also the induced drag.
- On Routing Flexibility of Wormhole-Switched Priority-Preemptive NoCsPublication . Nikolic, Borislav; Pinho, Luís Miguel; Indrusiak, LeandroFlit-level preemptions via virtual channels have been proposed as one viable method to implement prioritypreemptive arbitration policies in NoC routers, and integrate NoCs in the hard real-time domain. In recent years, researchers have explored several aspects of priority-preemptive NoCs, such as different arbitration techniques, different priority assignment methods (where applicable) and different workload mapping approaches, all with the common objective to use interconnect mediums more efficiently. Yet, the impact of different routing techniques on such a model is still an unexplored topic. Motivated by this reality, in this work we study the effects of routing flexibility on wormhole-switched priority-preemptive NoCs.
- Real-Time Dense Wired Sensor Network Based on Traffic ShapingPublication . Loureiro, João; Rangarajan, Raghuraman; Nikolic, Borislav; Indrusiak, Leandro; Tovar, EduardoXDense is a novel wired 2D-mesh grid sensor network system for application scenarios that benefit from densely deployed sensing (e.g. thousands of sensors per square meter). It was conceived for closed-loop cyber-physical systems (CPS) that require real-time actuation, like active flow control (AFC) on aircraft wing surfaces. XDense communication and distributed processing capabilities are designed such that they enable to extract complex features within bounded time and in a responsive manner. In this paper we tackle the issue of deterministic behavior of XDense. We present a methodology that uses traffic shaping heuristics to guarantee bounded communication delays and the fulfillment of memory requirements. We evaluate the model for varied network configurations and workload, and demonstrate the effectiveness of running real-time applications supported on XDense.