231,299 research outputs found

    Improving the Energy Efficiency of Software Systems for Multi-Core Architectures

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    International audienceThe ICT has an huge impact on the world CO2 emissions and recent study estimates its account to 2% of these emissions. This growing account emissions makes IT energy efficiency an important challenge. State-of-the-art has proven that the processor is the main power consumer. Processor are nowadays more and more complex and they are used in many hardware systems, such as computers or smart-phones. This thesis is thus focusing on the software energy efficiency for multi-core systems. In this paper, we therefore report our motivations to understand deeply their architectures for improving their energy efficiencies. Manufacturers have worked tremendously to improve performance and reduce power consumption of their processors. However a lot of things remains to do in the software side. We claim that energy-efficient softwares can play a deterministic role to reduce the IT carbon footprint. To answer this challenge, we are believing on the software-metric approach with a minimal hardware investment. For this purpose, an efficient, scalable and non-invasive tool is needed. As a result, we created PowerAPI, to provide fine-grained power estimations at process and code-level for optimizing the software energy efficiency automatically. This solution will help to identify clearly the energy leaks for optimizing automatically the power consumed by software

    Energy Efficiency in SDDC: Considering Server and Network Utilities

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    © 2020 IEEE. Software Defined Networking (SDN) has eased the management and control of networks through separation of the control and data planes. Software defined data centers (SDDC) automate the management of end systems which are physical machines and virtual machines. In data centers, although there is a vast work on minimizing power consumption of physical machines and virtual machine migration performance, energy efficiency of the network components is given little attention. In this paper, a software-based energy efficiency framework that jointly minimizes the power consumption of end systems and network components in SDDC is proposed. Moreover, a novel physical server utility interval based metric, namely Ratio for Energy Saving of Physical Machines (RESPM) which measures how energy efficient the physical servers with respect to virtual machines residing within is proposed. To jointly maximize network energy efficiency and RESPM values, an Integer Programming (IP) formulation has been introduced. Experiments conducted on real-world virtual migration traces show that the proposed framework jointly reduces the power consumption of end systems and network components. The system has shown an improvement of 9% in RESPM, 35% energy saving in Ratio of Energy Saving in SDN (RESDN), and more than 50% in links saving

    Challenges and complexities in application of LCA approaches in the case of ICT for a sustainable future

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    In this work, three of many ICT-specific challenges of LCA are discussed. First, the inconsistency versus uncertainty is reviewed with regard to the meta-technological nature of ICT. As an example, the semiconductor technologies are used to highlight the complexities especially with respect to energy and water consumption. The need for specific representations and metric to separately assess products and technologies is discussed. It is highlighted that applying product-oriented approaches would result in abandoning or disfavoring of new technologies that could otherwise help toward a better world. Second, several believed-untouchable hot spots are highlighted to emphasize on their importance and footprint. The list includes, but not limited to, i) User Computer-Interfaces (UCIs), especially screens and displays, ii) Network-Computer Interlaces (NCIs), such as electronic and optical ports, and iii) electricity power interfaces. In addition, considering cross-regional social and economic impacts, and also taking into account the marketing nature of the need for many ICT's product and services in both forms of hardware and software, the complexity of End of Life (EoL) stage of ICT products, technologies, and services is explored. Finally, the impact of smart management and intelligence, and in general software, in ICT solutions and products is highlighted. In particular, it is observed that, even using the same technology, the significance of software could be highly variable depending on the level of intelligence and awareness deployed. With examples from an interconnected network of data centers managed using Dynamic Voltage and Frequency Scaling (DVFS) technology and smart cooling systems, it is shown that the unadjusted assessments could be highly uncertain, and even inconsistent, in calculating the management component's significance on the ICT impacts.Comment: 10 pages. Preprint/Accepted of a paper submitted to the ICT4S Conferenc

    Feedback Controlled Software Systems

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    Software systems generally suffer from a certain fragility in the face of disturbances such as bugs, unforeseen user input, unmodeled interactions with other software components, and so on. A single such disturbance can make the machine on which the software is executing hang or crash. We postulate that what is required to address this fragility is a general means of using feedback to stabilize these systems. In this paper we develop a preliminary dynamical systems model of an arbitrary iterative software process along with the conceptual framework for stabilizing it in the presence of disturbances. To keep the computational requirements of the controllers low, randomization and approximation are used. We describe our initial attempts to apply the model to a faulty list sorter, using feedback to improve its performance. Methods by which software robustness can be enhanced by distributing a task between nodes each of which are capable of selecting the best input to process are also examined, and the particular case of a sorting system consisting of a network of partial sorters, some of which may be buggy or even malicious, is examined

    Spatial Modulation with Energy Detection: Diversity Analysis and Experimental Evaluation

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    In this paper, we present a non-coherent energy detection scheme for spatial modulation (SM) systems. In particular, the use of SM is motivated by its low-complexity implementation in comparison to multiple-input multiple-output (MIMO) systems, achieved through the activation of a single antenna during transmission. Moreover, energy detection-based communications restrict the channel state information to the magnitude of the fading gains. This consideration makes the design applicable for low-cost low-powered devices since phase estimation and its associated circuitry are avoided. We derive an energy detection metric for a multi-antenna receiver based on the maximum-likelihood (ML) criterion. By considering a biased pulse amplitude modulation, we develop an analytical framework for the SM symbol error rate at high signal-to-noise ratios. Numerical results show that the diversity order is proportional to half the number of receive antennas; this result stems from having partial receiver channel knowledge. In addition, we compare the performance of the proposed scheme with that of the coherent ML receiver and show that the SM energy detector outperforms its coherent counterpart in certain scenarios, particularly when utilizing non-negative constellations. Ultimately, we implement an SM testbed using software-defined radio devices and provide experimental error rate measurements that validate our theoretical contribution.Comment: This work has been submitted to an IEEE journal for possible publicatio
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