65,401 research outputs found

    _ Synthesis of Embedded Software Using Free-Choice Petri Nets

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    Software synthesis from a concurrent functional specification is a key problem in the design of embedded systems. A concurrent specification is well-suited for medium-grained partitioning. However, in order to be implemented in software, concurrent tasks need to be scheduled on a shared resource (the processor). The choice of the scheduling policy mainly depends on the specification of the system. For pure dataflow specifications, it is possible to apply a fully static scheduling technique, while for algorithms containing data-dependent control structures, like the if-then-else or while-do constructs, the dynamic behaviour of the system cannot be completely predicted at compile time and some scheduling decisions are to be made at run-time. For such applications we propose a Quasi-static scheduling (QSS) algorithm that generates a schedule in which run-time decisions are made only for data-dependent control structures. We use Free Choice Petri Nets (FCPNs), as underlying model, and define quasi-static schedulability for FCPNs. The proposed algorithm is complete, in that it can solve QSS for any FCPN that is quasi-statically schedulable. Finally, we show how to synthesize from a quasi-static schedule a C code implementation that consists of a set of concurrent tasks

    Semantics-Preserving Implementation of Synchronous Specifications Over Dynamic TDMA Distributed Architectures

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    International audienceWe propose a technique to automatically synthesize programs and schedules for hard real-time distributed (embedded) systems from synchronous data-flow models. Our technique connects the SynDEx scheduling tool and the Network Code toolchain in a seamless flow of automatic model transformations that go all the way from specification to implementation. Our contribution is the non-trivial connection between the models manipulated by SynDEx and by the Network Code toolchain, at both formal and tool level. We provide an algorithm for converting the data-dependent schedule tables output by SynDEx into Network Code programs which can be seen as an ``assembly code'' level for time-driven distributed real-time systems. The main difficulty is to ensure the preservation of both functionality and the real-time guarantees computed by SynDEx in the presence of clock drifts (which are abstracted away in the scheduling model of SynDEx). Existing tools can convert the resulting Network Code programs into software and hardware-accelerated execution units.Nous proposons une technique pour la synthèse automatique de programmes et ordonnancements pour des systèmes temps-réel (embarqués) distribués, à partir de spécifications synchrones flot de données

    Computational tasks in robotics and factory automation

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    The design of Manufacturing Planning and Control Systems (MPCSs) — systems that negotiate with Customers and Suppliers to exchange products in return for money in order to generate profit, is discussed.\ud \ud The computational task of MPCS components are systematically specified as a starting point for the development of computational engines, as computer systems and programs, that execute the specified computation. Key issues are the overwhelming complexity and frequently changing application of MPCSs

    MorphoSys: efficient colocation of QoS-constrained workloads in the cloud

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    In hosting environments such as IaaS clouds, desirable application performance is usually guaranteed through the use of Service Level Agreements (SLAs), which specify minimal fractions of resource capacities that must be allocated for unencumbered use for proper operation. Arbitrary colocation of applications with different SLAs on a single host may result in inefficient utilization of the host’s resources. In this paper, we propose that periodic resource allocation and consumption models -- often used to characterize real-time workloads -- be used for a more granular expression of SLAs. Our proposed SLA model has the salient feature that it exposes flexibilities that enable the infrastructure provider to safely transform SLAs from one form to another for the purpose of achieving more efficient colocation. Towards that goal, we present MORPHOSYS: a framework for a service that allows the manipulation of SLAs to enable efficient colocation of arbitrary workloads in a dynamic setting. We present results from extensive trace-driven simulations of colocated Video-on-Demand servers in a cloud setting. These results show that potentially-significant reduction in wasted resources (by as much as 60%) are possible using MORPHOSYS.National Science Foundation (0720604, 0735974, 0820138, 0952145, 1012798

    Energy-Aware Cloud Management through Progressive SLA Specification

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    Novel energy-aware cloud management methods dynamically reallocate computation across geographically distributed data centers to leverage regional electricity price and temperature differences. As a result, a managed VM may suffer occasional downtimes. Current cloud providers only offer high availability VMs, without enough flexibility to apply such energy-aware management. In this paper we show how to analyse past traces of dynamic cloud management actions based on electricity prices and temperatures to estimate VM availability and price values. We propose a novel SLA specification approach for offering VMs with different availability and price values guaranteed over multiple SLAs to enable flexible energy-aware cloud management. We determine the optimal number of such SLAs as well as their availability and price guaranteed values. We evaluate our approach in a user SLA selection simulation using Wikipedia and Grid'5000 workloads. The results show higher customer conversion and 39% average energy savings per VM.Comment: 14 pages, conferenc

    Providing Delay Guarantees in Bluetooth

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    Bluetooth polling, also referred to as Bluetooth MAC scheduling or intra-piconet scheduling, is the mechanism that schedules the traffic between the participants in a Bluetooth network. Hence, this mechanism is highly determining with respect to the delay packets experience in a Bluetooth network. In this paper we present a polling mechanism that provides delay guarantees in an efficient manner and we evaluate this polling mechanism by means of simulation. It is shown that this polling mechanism is able to provide delay guarantees while saving as much as possible resources, which can be used for transmission of best effort traffic or for retransmission
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