231,299 research outputs found
Improving the Energy Efficiency of Software Systems for Multi-Core Architectures
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
© 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
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
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
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
- …