Energy consumption reduction for asynchronous message-passing applications

This paper presents a new online frequency selecting algorithm for asynchronous parallel methods running over grids. It selects a vector of frequencies that gives the best tradeoff between energy consumption and performance. It also has a very small overhead and works without training and profiling. New energy and performance models are used in this algorithm to predict the execution time and the energy consumption of synchronous, asynchronous and hybrid iterative applications running over grids. The algorithm was evaluated on the Grid'5000 testbed while running a multi-splitting application that solves a 3D problem. The experiments show that applying synchronously the proposed frequency scaling algorithm to the asynchronous version of the application reduces its energy consumption up to 26.93% and speeds it up by 21.48%. Finally, the algorithm was compared to the Energy and Delay Product (EDP) method and it outperformed the latter in the energy reduction and performance trade-off for parallel asynchronous iterative methods.

CPU-GPU accelerator based heterogeneous cloud computing systems can give enhanced energy efficiency and performance. Both energy efficiency and performance parameters are the vital factors in achieving High Performance Computing (HPC). To completely understand the strength of heterogeneous cloud computing architectures, software must efficiently use CPU-GPU processing and their power conserves capability. Dynamic Voltage and Frequency Scaling (DVFS) technique can be used to enable power conserving capabilities of CPU-GPU core architectures. Therefore, to distribute task load between host CPUs and GPU accelerators and reduce energy consumption, here, we have introduced a Heterogeneous Dynamic Scheduling Minimized Makespan (HDSMM) using CPU-GPU cores for heterogeneous cloud computing devices. Here, DVFS technique is distributed into CPU-DVFS and GPU-DVFS, for efficient resource utilization and to exploit power conserving features. Our proposed HDSMM model presents precise modeling for performance and energy efficiency distribution and finest frequency to achieve either best performance or lowest power consumption. Experimental results verify the superiority of our proposed HDSMM model in terms of energy consumption, average execution time and average power for scientific benchmark Montage.

Deep neural networks (DNNs) have been widely applied in diverse applications, but the problems of high latency and energy overhead are inevitable on resource-constrained devices. To address this challenge, most researchers focus on the dynamic voltage and frequency scaling (DVFS) technique to balance the latency and energy consumption by changing the computing frequency of processors. However, the adjustment of memory frequency is usually ignored and not fully utilized to achieve efficient DNN inference, which also plays a significant role in the inference time and energy consumption. In this paper, we first investigate the impact of joint memory frequency and computing frequency scaling on the inference time and energy consumption with a model-based and data-driven method. Then by combining with the fitting parameters of different DNN models, we give a preliminary analysis for the proposed model to see the effects of adjusting memory frequency and computing frequency simultaneously. Finally, simulation results in local inference and cooperative inference cases further validate the effectiveness of jointly scaling the memory frequency and computing frequency to reduce the energy consumption of devices.

As high quality real-time service demands on smart device applications are rapidly increasing, offloading the application task to the edge server to reduce total response time is emerging as a key issue. Meanwhile, smart devices are very sensitive to the energy consumption (to maximize the battery lifetime), where various energy consumption schemes have been attempted to minimize the power profile, especially for computationally heavy tasks. In this paper, an energy consumption minimization scheme that adjusts both the offloading ratio and CPU operating frequency of the device based on a Dynamic Voltage and Frequency Scaling (DVFS) technique under delay constraint is proposed. Simulation results show that the proposed scheme minimizes the energy consumption of the device while satisfying the delay requirement.

Comparing with the cloud computing, mobile edge computing (MEC) can further decrease the latency and improve the stability of the networks. However, it is challenging for the edge servers to deal with the large computation task due to the limited computing capacity. In this study, we design a novel three-layer network architecture consisting of mobile devices, edge cloudlets, and helper cloudlets, where the computing data can be partially processed at the edge cloudlet and helper cloudlet. Based on this, a joint communication, offloading, and computation resource allocation problem is formulated to minimise the computation cost and energy consumption. Due to its difficulty to directly solve the formulated problem, we first propose an offloading scheme to obtain the closed-form solutions for the optimal offloading data size. Next, we decompose the optimisation problem into two subproblems: (i) for the cloud execution, we dynamically adjust the data transmission rate according to the stochastic channel condition, (ii) for the mobile execution, the energy consumption can be further reduced by applying the dynamic voltage and frequency scaling technique. Finally, the numerical results demonstrate the efficiency of the proposed scheme, and show the performance gains in terms of delay, computation cost and energy consumption.

Energy-efficient VM opening algorithms for real-time workflows in heterogeneous clouds

NoC (Network-on-Chip) in recent times has been broadly used in majority of present multi-core (MC) processing environment (i.e., processor) (especially in cloud computing servers). Then, SoCs (System-on-Chips), as a scalable and flexible strategy to the widespread integration of higher number of element in the chips. Nonetheless, a main issue is reliable processing, performance efficiency and energy efficacy perquisite of BigData processing framework. This work assume self-aware MC architectures that autonomously adjust or optimize their performance to accommodate users quality of service (QoS) performance requirement, job execution performance, energy efficiency, and resource accessibility. Numerous researchers are concerned about the lack of energy conservation in cloud computing environment and hence numerous power efficient technologies are introduced by different researchers to protect environment by enormous amount of power dissipation and enhance the performance of the environment. However, these power efficient technologies requires enormous amount of interaction cost between inter-processors. Moreover, these technologies provides insufficient results and energy consumption of cloud computing devices cannot be reduced largely due to enormous amount of memory utilization, routing etc. For overcoming research challenges, this work present a novel performance and energy balanced scheduling (PEBS) approach in cloud environment based on Dynamic voltage and Frequency Scaling (DVFS) technique is proposed. Experiment outcome shows PEBS_DVFS model attains good trade-off between system performance and energy consumption in multicore cloud computing (CC) architectures when compared with existing model.

In this paper, new multi-objective optimization algorithm is proposed. It optimizes the execution time, the energy consumption and the cost of booked nodes in the grid architecture at the same time. The proposed algorithm selects the best frequencies depends on a new optimization function that optimized these three objectives, while giving equivalent trade-off for each one. Dynamic voltage and frequency scaling (DVFS) is used to reduce the energy consumption of the message passing parallel iterative method executed over grid. DVFS is also reduced the computing power of each processor executing the parallel applications. Therefore, the performance of these applications is decreased and so on the payed cost for the booking nodes is increased. However, the proposed multi-objective algorithm gives the minimum energy consumption and minimum cost with maximum performance at the same time. The proposed algorithm is evaluated on the SimGrid/SMPI simulator while running the parallel iterative Jacobi method. The experiments show that it reduces on average the energy consumption by up to 19.7 %, while limiting the performance and cost degradations to 3.2 % and 5.2 % respectively.

Energy consumption has become a key metric for evaluating how good an embedded system is, alongside more performance metrics like respecting operation deadlines and speed of execution. Schedulability improvement is no longer the only metric by which optimality is judged. In fact, energy efficiency is becoming a preferred choice with a fundamental objective to optimize the system’s lifetime. In this work, we propose an optimal energy efficient scheduling algorithm for aperiodic real-time jobs to reduce CPU energy consumption. Specifically, we apply the concept of real-time process scheduling to a dynamic voltage and frequency scaling (DVFS) technique. We address a variant of earliest deadline first (EDF) scheduling algorithm called energy saving-dynamic voltage and frequency scaling (ES-DVFS) algorithm that is suited to unpredictable future energy production and irregular job arrivals. We prove that ES-DVFS cannot attain a total value greater than C/000000, where 000000 is the minimum speed of any job and C is the available energy capacity. We also investigate the implications of having in advance, information about the largest job size and the minimum speed used for the competitive factor of ES-DVFS. We show that such advance knowledge makes possible the design of semi-on-line algorithm, ES-DVFS**, that achieved a constant competitive factor of 0.5 which is proved as an optimal competitive factor. The experimental study demonstrates that substantial energy savings and highest percentage of feasible job sets can be obtained through our solution that combines EDF and DVFS optimally under the given aperiodic jobs and energy models.

The resource-constrained task scheduling problem has been one of the popular research topics in cloud computing systems. By employing the dynamic voltage and frequency scaling (DVFS) techniques, the task scheduling can be further constrained by energy consumption. The paper investigates the DAG task scheduling considering both the resource and energy constraints in heterogeneous distributed systems. The objective is to minimize the scheduling length. An energy-constrained task scheduling framework is employed, where tasks are initially scheduled according to their upward rank values. Then two heuristics are proposed to improve the initial solution, namely, the simulated annealing local search method and the frequency adjustment method. Experiments are conducted by testing a large number of instances with multiple parameter settings, and the results show that the proposed algorithms are effective and efficient.

Models of energy consumption and performance are necessary to understand and identify system behavior, prior to designing advanced controls that can balance out performance and energy use. This paper considers the energy consumption and performance of servers running a relatively simple file-compression workload. We found that standard techniques for system identification do not produce acceptable models of energy consumption and performance, due to the intricate interplay between the discrete nature of software and the continuous nature of energy and performance. This motivated us to perform a detailed empirical study of the energy consumption and performance of this system with varying compression algorithms and compression levels, file types, persistent storage media, CPU DVFS levels, and disk I/O schedulers. Our results identify and illustrate factors that complicate the system's energy consumption and performance, including nonlinearity, instability, and multi-dimensionality. Our results provide a basis for future work on modeling energy consumption and performance to support principled design of controllable energy-aware systems.

Nowadays, modern data centers are seeking for importing renewable energy together with conventional energy in order to be more environment-friendly and to reduce operation expenditures. Meanwhile, considering the fact that electricity prices and renewable energy generations are diverse in time and geography, a task scheduling strategy should be designed to ensure the efficient and economic operations of data centers. In this paper, an optimal task placement strategy is presented for geo-distributed data centers powered by mixed renewable and conventional energies with dynamic voltage and frequency scaling technique. We aim at minimizing the total electricity cost and making full use of the renewable energy so as to construct green and economic data centers. The optimal task placement problem is formulated as a mixed integer nonlinear problem (MINLP), in which the quality-of-service constraint is restricted by an M/G/1 queuing model. To tackle the complexity of the MINLP, we first transform it into a tractable form, and then develop an optimal sever activation configuration and task placement algorithm to solve it. The proposed algorithm can obtain the global optimal solution of the electricity minimization problem and meanwhile dramatically reduce the complexity of the problem solving. Finally, evaluations based on real-world traces exhibit impacts of different system parameters on the electricity cost and sever activation configurations, which prove the superiority of our proposed algorithm and provide us some illuminations on how to build cost-effective and eco-friendly data centers.

In this paper, we propose an energy-aware MPEG-4 FGS video streaming system with client feedback. In this client-server system, the battery-powered mobile client sends its maximum decoding capability (i.e., its decoding aptitude) to the server in order to help the server determine the additional amount of data (in the form of enhancement layers on top of the base layer) per frame that it sends to the client, and thereby, set its data rate. On the client side, a dynamic voltage and frequency scaling technique is used to adjust the decoding aptitude of the client while meeting a constraint on the minimum achieved video quality. As a measure of energy efficiency of the video streamer, the notion of a normalized decoding load is introduced. It is shown that a video streaming system that maintains this normalized load at unity produces the optimum video quality with no energy waste. We implemented an MPEG-4 FGS video streaming system on an XScale-based testbed in which a server and a mobile client are wirelessly connected by a feedback channel. Based on the actual current measurements in this testbed, we obtain an average of 20% communication energy reduction in the client by making the MPEG-4 FGS streamer energy-aware.

We present a dynamic voltage and frequency scaling technique within SoCs for per-core power management: the architecture allows for individual, self triggered performance-level scaling of the processing elements (PEs) within less than 100ns. This technique enables each core to adjust its local supply voltage and frequency depending on its current computational load. A test chip has been implemented in 28nm CMOS technology, as prototype of the SpiNNaker2 neuromorphic many core system, containing 4 PEs which are operational within the range of 1.1V down to 0.7V at frequencies from 666MHz down to 100MHz; the effectiveness of the power management technique is demonstrated using a standard benchmark from the application domain. The particular domain area of this application specific processor is real-time neuromorphics. Using a standard benchmark - the synfire chain - we show that the total power consumption can be reduced by 45%, with 85% baseline power reduction and a 30% reduction of energy per neuron and synapse computation, all while maintaining biological real-time operation.

Mobile cloud computing (MCC) as an emerging and prospective computing paradigm, can significantly enhance computation capability and save energy of smart mobile devices (SMDs) by offloading computation-intensive tasks from resource-constrained SMDs onto the resource-rich cloud. However, how to achieve energy-efficient computation offloading under the hard constraint for application completion time remains a challenge issue. To address such a challenge, in this paper, we provide an energy-efficient dynamic offloading and resource scheduling (eDors) policy to reduce energy consumption and shorten application completion time. We first formulate the eDors problem into the energy-efficiency cost (EEC) minimization problem while satisfying the task-dependency requirements and the completion time deadline constraint. To solve the optimization problem, we then propose a distributed eDors algorithm consisting of three subalgorithms of computation offloading selection, clock frequency control and transmission power allocation. More importantly, we find that the computation offloading selection depends on not only the computing workload of a task, but also the maximum completion time of its immediate predecessors and the clock frequency and transmission power of the mobile device. Finally, our experimental results in a real testbed demonstrate that the eDors algorithm can effectively reduce the EEC by optimally adjusting the CPU clock frequency of SMDs based on the dynamic voltage and frequency scaling (DVFS) technique in local computing, and adapting the transmission power for the wireless channel conditions in cloud computing.