Research Article RVLBPNN: A Workload Forecasting Model for …downloads.hindawi.com/journals/sp/2016/5635673.pdf · Research Article RVLBPNN: A Workload Forecasting Model for Smart

Research ArticleRVLBPNN: A Workload Forecasting Model forSmart Cloud Computing

Yao Lu,1 John Panneerselvam,2 Lu Liu,1,2 and YanWu1,3

1School of Computer Science and Telecommunication Engineering Jiangsu University, Jiangsu, China2Department of Computing and Mathematics, University of Derby, Derby, UK3Department of Computer Science, Boise State University, Boise, USA

Correspondence should be addressed to Lu Liu; [email protected]

Received 28 July 2016; Accepted 19 September 2016

Academic Editor: Wenbing Zhao

Copyright © 2016 Yao Lu et al. This is an open access article distributed under the Creative Commons Attribution License, whichpermits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Given the increasing deployments of Cloud datacentres and the excessive usage of server resources, their associated energy andenvironmental implications are also increasing at an alarming rate. Cloud service providers are under immense pressure tosignificantly reduce both such implications for promoting green computing. Maintaining the desired level of Quality of Service(QoS) without violating the Service Level Agreement (SLA), whilst attempting to reduce the usage of the datacentre resources isan obvious challenge for the Cloud service providers. Scaling the level of active server resources in accordance with the predictedincoming workloads is one possible way of reducing the undesirable energy consumption of the active resources without affectingthe performance quality. To this end, this paper analyzes the dynamic characteristics of the Cloudworkloads and defines a hierarchyfor the latency sensitivity levels of the Cloud workloads. Further, a novel workload prediction model for energy efficient CloudComputing is proposed, named RVLBPNN (Rand Variable Learning Rate Backpropagation Neural Network) based on BPNN(Backpropagation Neural Network) algorithm. Experiments evaluating the prediction accuracy of the proposed prediction modeldemonstrate that RVLBPNN achieves an improved prediction accuracy compared to the HMM and Naıve Bayes Classifier modelsby a considerable margin.

1. Introduction

Cloud Computing is emerging as a prominent computingparadigm for various business needs, as it is known to be alow-cost any-time computing solution. The on-demand ser-vice access features of the Cloud Computing help the Cloudclients to adopt or transform their business model to Clouddatacentres for computing and storage resources [1]. Thisincreasing number of Cloud adoptions by various businessdomains over the recent years is also reflected in the increasein the number of Cloud service providers. An immediateimpact of this is that Cloud datacentres are addressed tobe one of the major sources of energy consumers [2] andenvironmental pollutants. To this end, Cloud datacentres areaddressed to be causing energy, economic, and environmen-tal impacts to an irresistible margin. It has been reported [3]that ICT (Information Communication Technology) energy

consumption will contribute up to 50% of the total energyexpenditures in the United States in the next decade, whichwas just 8% in the last decade. Energy efficient computinghas been promoted and researched under various dimensionsfor the purpose of reducing the energy consumption levels ofthe datacentre whilst processing workloads and cooling theserver resources. It is worthy of note that cooling system in atypical Cloud datacentre would incur considerable amount ofenergy cost of those spent towards the actual task execution[4].Thus it is apparent that energy efficient CloudComputingis one of demanding characteristics of Cloud Computing.

Resource management driven by forecasting the futureworkloads is one of the possible ways of achieving energy effi-ciency inCloudComputing. In general, the intrinsic dynamic[5] nature of the Cloud workloads imposes complexities inscheduling, resource allocation, and executing workloads inthe datacentres. Predicting the nature of the future workloads

Hindawi Publishing CorporationScientific ProgrammingVolume 2016, Article ID 5635673, 9 pageshttp://dx.doi.org/10.1155/2016/5635673

2 Scientific Programming

can help reduce the energy consumption levels of the serverresources by the way of effectively scheduling the incom-ing workloads with the most appropriate level of resourceallocation. Alongside energy efficient computing, predictiveanalytics in Cloud Computing also benefits [5] effectiveresource utilization, optimum scalability of resources, avoid-ing process failures, capacity planning, network allocation,task scheduling, load balancing, performance optimizationandmaintaining the predetermined QoS (Quality of Service)and SLAs (Service Level Agreements), and so forth.

Owing to the extravagant dynamicity of Cloud work-loads, understanding the characteristic behaviors of theCloud workloads at the datacentre environment is often acomplex process. Mostly, Cloud workloads are of shorterduration and arrive more frequently at the datacentres andare generally not computationally more intensive unlike sci-entific workloads. Furthermore, every submitted workloadsare bound to a certain level of latency sensitiveness [6]which decides the time within which the workload has tobe processed. Workloads with increased latency sensitivitylevels usually demand quicker scheduling from the providers.This implies that an effective predictionmodel should possessthe qualities of understanding the inherent characteristicsand nature of the Cloud workloads and their correspondingbehaviors at the datacentres.

Despite the existing and ongoing researches, Cloud Com-puting still demands extensive analyses of the Cloud entitiesfor the purpose of modelling the relationship between theusers and their workload submissions and the associatedresource requirements. An effective prediction model shouldnecessarily incorporate the knowledge of three importantcharacteristic events in a datacentre environment in orderto achieve reliable level of prediction accuracy. Firstly, thevolume and the nature of the workloads submitted aredriven by the users based on their requirements and resourcedemands. Increased amounts of jobs submissions obviouslydemand increased amounts of resource allocation and thuscauses increased energy expenditures. Secondly, the actualexecution of the workloads would not necessarily consumeall the allocated resources. The immediate implication isthat increased proportions of allocated resources remainidle during task execution and incur undesirable energyconsumptions. Finally, the user behavioral pattern of job sub-mission and associated resource consumption are subjectedto change over time.

The intrinsic dynamism of both the Cloud workloads andthe server resources should be effectively captured [7] bythe prediction model over a prolonged observation period.Existing works in analyzing the intrinsic characteristics ofthe Cloud entities have not contributed suffice inferences[5, 8, 9] required for an effective prediction model. Impreciseknowledge of such aforementioned parameters of the Cloudentities would increase the prediction error margin, whichwould directly affect the Quality of Service (QoS) by violatingthe Service Level Agreement (SLA). With this in mind, thispaper proposes a novel forecast model named RVLBPNN(Rand Variable Learning Rate Backpropagation Neural Net-work), based on an improved BPNN (BPNeural Network) foraccurately predicting the user requests. Exploiting the latency

sensitivity levels of theCloudworkloads, our proposedmodelpredicts the user requests anticipated in the near future in alarge-scale datacentre environment.

The rest of this paper is organized as follows: Section 2introduces the previous works in Cloud workload predictionmodelling. Section 3 presents a background study on Cloudworkloads, exhibiting the dynamic nature of the Cloudworkloads. The computational latencies affecting the Cloudworkloads are defined in Section 4 and Section 5 proposesour prediction model based on the modified BP NeuralNetwork. Our experiments are presented in Section 6 andSection 7 concludes this paper along with our future researchdirections.

2. Related Works

A number of researches are being conducted with the moti-vation of promoting green computing in the recent past. Forinstance, the approach of capacitymanagement andVM(Vir-tual Machine) placement have been the strategies of [10, 11].A workload placement scheme, called BADP, combines task’sbehavior to place data for improving locality at the cacheline level. Further, [11] proposes a remaining utilization-aware(RUA) algorithm for VM placement. In general, workloadplacement and task allocation can be more effective whendriven by a proactive prediction of the incoming workloads.Time series [12] approach incorporates the repeatable behav-iors such as periodicity and timely effects of the variousCloudentities such as VMs and users and explores the temporaland spatial correlations in order to provide the predictionresults. However, such technique usually explores the entitiesindividually and often leads to inaccurate results resultingfrom the random behaviors of the individual entities.

A multiple time series approach [13] has been proposedto improve the prediction accuracy, by the way of analyzingthe Cloud entities at the group level rather individually. Non-linear time series approach works with the assumption thatthe observations are real valued and such techniques oftenrequire special emphasis on extracting the chaotic invariantsfor prediction analysis. Autoregression (AR) is a predictiontechnique [14] which usually predicts the next state transitionby recursively acting on the prediction values. However, ARmethod has a conspicuous shortcoming that the predictionerrors will be accumulated for long term prediction analysisbecause of the recursive effect. Another drawback of ARmethods is that they only deliver accurate forecasts fordatasets characterized with reasonable periodicity, which isshown in [15], where a number of different linear predictionmodels based on AR have been deeply analyzed. Poissonprocess [16] models the incoming workload arrival patternfor prediction analysis and has the capability of capturingcomplex nonexponential time varying workload features.Moving average approaches [14, 16] such as first-order andsecond-order moving average techniques used for predictionanalysis cannot capture important features required to adaptto the load dynamics.

Recently, Bayes and Hidden Markov Modelling (HMM)[5] approaches were analyzed in our earlier works for eval-uating their prediction efficiency in Cloud environments.

Scientific Programming 3

Byes technology predicts the future samples based on apredefined evidencewindow.The adjacent samples containedin the evidence window should be mutually correlated fordelivering a reliable prediction output.Thus Bayes model willlose efficiency in a dynamic Cloud environment. However,Bayes model could still be deployed in situations where thereare less fluctuations among the workload behavior. HMM isa probabilistic approach which is used to predict the futuresate transition from the current state. In spite of the dynamicnature of the Cloud workloads, probabilistic approach maynot scale well for predicting the future workloads with a reli-able level of prediction accuracy. Despite the existing works,Cloud Computing still demands a smart prediction modelwith the qualities of relative high precision and the capacityof delivering a reliable level of prediction accuracy. Withthis in mind, this paper proposes a novel prediction modelnamed RVLBPNN. Exploiting the workload characteristics,our proposed model achieves a reliable level of predictionaccuracy. Our proposed model has been sampled and testedfor accuracy based on a real life Cloud workload behaviors.

3. Background

3.1. Cloud Workloads. Cloud workloads arrive at Clouddatacentres in the form of jobs [15] submitted by the users.Every job includes certain self-defining attributes such asthe submission time, user identity, and its correspondingresource requirements in terms of CPUandmemory. A singlejob may contain one or more tasks, which are scheduled forprocessing at the Cloud servers. A single task may have oneormore process requirements. Tasks belonging to a single jobmay also be scheduled to differentmachines but it is desirableto run multiple processes of a single task in a single machine.Tasks are also bound to have varied service requirements suchas throughput, latency, and jitter, though they belong to thesame job.The tasks belonging to the same job not necessarilyexhibit higher correlating properties among them.Thus, taskswithin the same job might exhibit greater variation in theirresource requirements. Tasks might also interact among eachother during their execution. Furthermore, two jobs with thesame resource requirementsmay not be similar in their actualresource utilization levels because of the variation foundamong the tasks contained within the jobs. Based on theresource requirements, tasks are scheduled either within thesame or across different servers. Usually, the provider recordsthe resource utilization levels of every scheduled task andmaintains the user profiles.

The attributes encompassed by theCloudworkloads, suchas type, resource requirements, security requirements, hard-ware, and network constraints, can be exploited to derive thebehaviors the Cloud workloads. Interestingly, Cloud work-loads behave distinctively with different server architectures.Such distinctive workload behaviors with different serverarchitectures strongly influence the CPU utilization, with thememory utilization generally remaining stable across most ofthe server architectures. Thus the resource utilization highlyvaries across the CPU cores compared to thememory or disc,as the disc utilization mostly shows similar utilization pat-terns across different server architectures.Thus the behaviors

of workloads at the Cloud processing environment arestrongly correlated with the CPU cores compared to RAMcapacity of the machines at the server level. The capacitylevels of CPU and memory in a physical server usuallyremain static. Resource utilization levels are more dynamicand vary abruptly under different workloads. Such dynamicparameters of the server architectures are usually calculatedas the measure of the number of cycles per instructionfor CPU and memory access per instruction for memoryutilizations, respectively. Thus the task resource usage isusually expressed as a multidimensional representation [5]encompassing task duration in seconds, CPU usage in cores,and memory usage in gigabytes. It is commonly witnessedthat most of the allocated CPU and memory resource are leftunutilized during task execution.

3.2. Characterizing Workloads. User demand often changesover time which reflects the timely variations of the resourceconsumption levels of the workloads generated as they aredriven by the users. User demands are generally influencedby the time-of-the-day effects, showing a repeating pattern[13] in accordance to the changing business behaviors of theday and by the popular weekend effects showing weekenddeclines and weekday increase trend in the arrival of theworkloads. The relationships [17] between the workloadsand user behaviors are primarily the integral component inthe understanding of the Cloud-based workloads and theirassociated energy consumptions.

Different workloads will have different processingrequirements such as CPU, memory, throughput, and exe-cution time, and this variation results from the characteristicbehaviors of different users. Nowadays, Cloud environmentsare more heterogeneous composing different servers withdifferent processing capacities. In order to satisfy the diverseoperational requirements of the Cloud user demands, nor-malization of this machine heterogeneity is now becomingan integral requirement of the Cloud providers, by which vir-tually homogenizing the heterogeneous server architecturesand thereby eliminating the differentiation found in both thehardware and the software resources. In general, the differentforms of workloads from the provider’s perspectives includecomputation intensive with larger processing and smallerstorage, memory intensive with larger storage and smallerprocessing, workloads requiring both larger processing andlarger storage, and communication intensive with morebandwidth requirements. Workloads are usually measuredin terms of the user demands, computational load on theservers, bandwidth consumption (communication jobs), andthe amount of storage data (memory jobs). User demandprediction modelling requires an in depth quantitativeand qualitative analysis of the statistical properties andbehavioral characteristics of the workloads including joblength, job submission frequency, and resource consumptionof the jobs, which insists that the initial characterizationof the workloads is more crucial in developing an efficientpredictionmodel. Rather than the stand-alone analysis of theabove stated workload metrics, modelling the relationshipsbetween them across a set of workloads is more significant inorder to achieve more reliable prediction results. Statistical


properties [18] of the workloads are more significant forthe prediction accuracy since they remain consistent inlonger time frames. Some of the important characteristics ofCloud workloads affecting prediction accuracy include joblength, job submission frequency, resource request levels, jobresource utilization, and self-similarity.

3.3. Categorizing Workloads. In the Cloud Computing ser-vice concept, the workload pattern, the Cloud deploymenttypes (public, private, hybrid, and community), and theCloud service offering models (SaaS, PaaS, and IaaS) areclosely interconnectedwith each other. From the perspectivesof the Cloud service providers, the incoming Cloud work-loads can be categorized into five major types [9] as static,periodic, unpredictable, continuously changing, and once-in-a-lifetime workloads. Static and periodic workloads usuallyfollow a predictable pattern in their arrival frequency. Con-tinuously changing workloads exhibit a pattern of definitevariations characterized by regular increasing and decliningtrend in their arrival frequencies. Unpredictable workloadsexhibit a random behavior in their arrival frequency andare the most challenging type of workloads for predictionanalysis. Once-in-a-lifetime workloads are the rarely arrivingworkloads and their submissions are mostly notified by theclients.

4. Workload Latency

Latency plays an important role at various levels of processingthe workloads in a Cloud processing infrastructure. Thispaper mainly focuses the influence of the workload latencysensitivity upon prediction accuracy. The most dominatingtypes of latencies are the network latency and the dispatchinglatency, both of which actually result from the geographicaldistribution of the users and the Cloud datacentres. Both ofthese latencies depend on the Round Trip Time (RTT) [19],which defines the time interval between the user requestsand the arrival of the corresponding response. Anothertype of latency existing in the process architecture is thecomputational latency which is the intracloud latency [20]found among the processing VMs located within a singledatacentre. This latency depends on both the software andthe hardware components [6, 21] such as CPU architecture,runtime environment, and memory, guests and host operat-ing system, instruction set, and hypervisor used. CPU archi-tecture, Operating System, and the scheduling mechanismsare the most dominating factors of this type of in-housecomputing latency, and efficient handling of such resourceshelps reducing the impacts of the computational latencies.

Jobs submitted at the Cloud datacentre undergo variouslevels of latencies depending on the nature of their processrequirements and the end-user QoS expectations. Since asingle job might contain a number of tasks, the latency sensi-tivity of every single tasks has to be treated uniquely. A singledefinition of the computing latency cannot fit all types of jobsor tasks, since every job is uniquely viewed at the datacentre.For instance, processing a massive scientific workload mayspan across several days or months, in which latencies ofa few seconds are usually acceptable. Common example of

the latency sensitive workloads is the World Wide Web,among which different applications have different latencylevels. The acceptable level of latencies is usually the measureof the end-user tolerances. Workloads resulting from userssurfing the internet are generally latency-insensitive. Jobsincluding online gaming and stock exchange data are thecommonly witnessed latency sensitive applications. The levelof sensitivity is determined by the allowed time-scale forthe providers to provide an undisrupted execution of theworkloads for delivering the desired levels of QoS, rangingfrom a few microseconds to a few tens of microsecond end-to-end latencies.

The taxonomy of the latency levels of the Cloud work-loads studied in this paper are attributed from level 0 repre-senting the least latency sensitive tasks to level 3 representingthe most latency sensitive tasks. Least latency sensitive tasks(level 0) are nonproduction tasks [22] such as developmentand nonbusiness critical analyses, which do not have asignificant impact on the QoS even if these jobs are queued atthe back end servers. Level 1 tasks are the next level of latencysensitive tasks and are generally the machine interactiveworkloads. Level 2 tasks are the real timemachine interactiveworkloads and the latency tolerance levels of these tasks stayat tens of milliseconds. Level 3 tasks are the most latencysensitive tasks with latency tolerance levels at the range ofsubmilliseconds, and are generally the revenue generatinguser requests such as stock and financial analysis. Workloadscharacterizing an increased level of latency sensitivity areusually treated with higher scheduling priorities at the data-centres. Latency analysis has a prime importance in greeningthe datacentre, since every job or task submitted to the Cloudhas its own level of latency tolerances, directly affecting notonly the various workload behaviors at the datacentres butalso the end-user QoS satisfaction.

Based on our earlier analysis conducted on a Clouddataset [23], we perform a latency aware quantification ofthe jobs submitted to the datacentre comprising a total of46093201 tasks in our recent work [24]. Figure 1 illustratesa day-wise submission of tasks across the observed 28 days.Figure 2 quantifies the total number of task submissions interms of their latency sensitivity levels. It can be observedthat most of the task submissions are least latency sensitiveaccounting for 79.52% of the total task submissions, followedby level 1, level 2, and level 3 with 12.46%, 7.54%, and 0.47%,respectively.

5. Proposed Prediction Model

This section describes our novel prediction model aimedat predicting the anticipated workloads in a large-scaledatacentre environment.

5.1. BP Neural Network Method. BP Neural Network is amultilayer hierarchical network composed of upper neu-rons and fully associated lower neurons. Upon training theinput samples into this multilayer network structure, thetransformed input values are propagated from the inputlayer through the middle layer, and the values are outputtedby the neurons in the output layer. The error margins


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between the actual and the expected output are normalizedby the way of the output neurons adjusting the connectionweights of the neurons in both the middle layer and theinput layer. This back propagation mechanism of connectionweight adjustment enhances the correctness of the networkresponses of the neurons to the input values. As the BPalgorithm implements a middle hidden layer with associatedlearning rules, the network neurons can effectively identifythe hidden nonlinear pattern among the input samples.

5.2. BP Neural Network Architecture. A typical neuronmodelcan be derived according to characteristics of the neu-rons [25–28], which is shown in Figure 3. In this figure,𝑋1, 𝑋2, . . . , 𝑋𝑛 are 𝑛 input data to the neurons; 𝑎𝑖1, 𝑎𝑖2, . . . , 𝑎𝑖𝑛are the weight factor of 𝑋1, 𝑋2, . . . , 𝑋𝑛, respectively; 𝑔() isa nonlinear function; 𝑂𝑖 is the output result; and 𝜆𝑖 is thethreshold.

Based on the above neuron structure, wemake𝑂𝑖 = 𝑔(𝑃𝑖),where, 𝑃𝑖 = ∑

𝑛𝑗=1 𝑎𝑖𝑗𝑋𝑗 − 𝜆𝑖. In the formula, 𝑋 represents the

input vector, 𝑎𝑖 represents the connection weight vector forneuron 𝑖, and 𝑃𝑖 is the input of the neurons. In most cases,𝜆𝑖 is considered to be the 0th input of the neuron. Thus, wecan get a simplified equation of the above expression, whichis shown in formula (1). In this equation, value𝑋0 = −1, and𝑎𝑖0 = 𝜆𝑖.

𝑃𝑖 =𝑛

∑𝑗=0

𝑎𝑖𝑗𝑋𝑗. (1)

𝜆i

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Figure 3: Neuron model.

5.3. An Improved BPNeural Network Algorithm for Prediction.BPNN can effectively extract the hidden nonlinear relation-ships among the Cloud workloads. However, BPNN with afixed learning rate cannot extract this nonlinear relationshipsamong the samples of large datasets, since BPNN has aslow convergence rate for large-scale datasets in the range ofBig Data. A modified BP algorithm named VLBP (variablelearning rate backpropagation) has been proposed to enhancethis convergence rate [29]. In comparison with the BPalgorithm, VLBP has a characteristic enhancement in boththe computation speed and precision of the output. But theVLBP algorithm can be susceptible to several numbers oflocal minima resulting from the irregular shake surface error.This slows down the update process of Mean Square Error(MSE) and increases the presence of local minimum points.This results in a higher approximation precision despitethe improvement in the convergence rate. VLBP exhibits afluctuating and slower learning process and increases thelength of the computation.

This necessitates further improvements in the BP Neu-ral Networks for the purpose of enhancing its predictionefficiency whilst training large datasets. This paper proposesa novel prediction method using a modified BP algorithmby incorporating variant conceptions of a genetic algorithm.Our proposed prediction method effectively adjusts thelearning rate of the neurons to a certain probability inaccordance with the trend of theMSE during the execution ofthe VLBP algorithm.The learning ratemay not be changed ormultiplied by the factor 𝜌 greater than 1 when MSE increasesbeyond the set threshold 𝜁.

Our proposed prediction algorithm is described as fol-lows:

(1) Generate a random number rand(𝑢) (0 < rand(𝑢) <1).

(2) If rand(𝑢) is less than a defined value (set as 0.8 inexperiments), then execute VLBP algorithm.

(3) If rand(𝑢) is greater than the defined value, else ifMSEhas increased, then the learning rate is multiplied by afactor greater than 1 despiteMSE exceeding 𝜁 or not; ifMSE decreases after updating the connection weight,then the learning rate ismultiplied by a factor between0 and 1.

We named our proposed algorithm as RVLBPNN (RandVariable Learning Rate Backpropagation Neural Network).


Through thismethod, the learning rate of the neuronswill notbe decreased at any time resulting from the slow renewal ofMSEnear the localminimumpoint. But, there is also a certainprobability of increasing the learning rate of the neurons.RVLBP algorithm can identify the global minimum pointby effectively avoiding the local minimum points. Thus ourproposed algorithm reduces the presence of local minimumpoints during the learning process, thereby improving thelearning efficiencies of the network neurons.

6. Performance Evaluation

6.1. Experiment Sample. This section demonstrates theefficiency of our proposed prediction model based onRVBLPNN. We train the input data sample to predict theanticipated values in the near future representing the futureworkloads expected to arrive at the datacentre. The exper-iment samples are trained in MATLAB 7.14 and the testdatasets used are the publically available Google workloadtraces [23]. The datasets are a collection of 28 days of Googleusage data workloads consisting of 46093201 tasks compris-ing CPU intensive workloads, memory-intensive workloads,and both CPU andmemory-intensive workloads.The datasetparameters include time, job id, parent id, number of cores(CPU workloads), and memory tasks (memory workloads),respectively, to define the sample attributes. We comparethe prediction efficiencies of our proposed prediction modelagainst the efficiencies of HiddenMarkovModel (HMM) andNaıve Bayes Classifier (NBC); both of them were evaluatedin our earlier works [5]. All the three models are evaluatedfor their efficiencies in predictingmemory andCPU intensiveworkloads accordingly. We train the prediction model with aset of 10 samples and contrast the prediction output with theactual set of successive 10 samples.

MATLAB simulation environment provides a built-inmodel for RVLBPNN technique, modelling RVLBPNN asa supervised learning. The Neural Network is comprisedof a three-layer network structure. This three-layer NeuralNetwork can approximate any type of nonlinear continuousfunction in theory. We ultimately use 10 input nodes, 12hidden nodes, and 10 output nodes through a number ofiterations for enhancing the prediction accuracy. The datasamples are normalized and imploded in the interval (0, 1).“logsig” function is selected as the activation function ofinput layer, hidden layer, and the output layer, so that thealgorithm exhibits a good convergence rate. Further, variablelearning rate and random variable learning rate are adopted,respectively. This experiment uses 100,000 workload datasamples as the training data and another 100000 data samplesas the reference data. The prediction accuracy is the measureof correlations between the predicted and actual set of samplevalues.

6.2. Result Analysis and Performance Evaluation

6.2.1. Memory Workloads Estimation. Figure 4 depicts theestimation results of RVLBPNN, HMM, and NBC model,respectively, in terms of their prediction accuracy whilst pre-dicting the memory-intensive workloads.The number of test

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Figure 5: Prediction accuracy for memory-intensive workloads.

samples (𝑥-axis) are plotted against the prediction accuracy(𝑦-axis) for the three models; every set of sample consistsof 10000 workload samples. For presenting the test resultswith a better interpretation, the sample results are sortedascendingly from 1 to 10 based on the prediction results.The average accuracy percentage in estimating the memory-intensive workloads without considering the latency levels ofindividual workloads for NBC, HMM, and RVLBPNN are47.69%, 57.77%, and 61.71%, respectively, as shown in Figures4 and 5. It is evident from Figures 4 and 5 that the RVLBPNNexhibits a better prediction accuracy than both HMM andNBC techniques. It can be depicted from the estimationresults that our proposed RVLBPNNmodel is demonstratinga minimum of 3% prediction accuracy better than HMM and13% better than NBC, respectively.

This improved prediction accuracy of the RVLBPNNmodel is attributed to its ability of capturing the intrinsicrelationship features among the arriving Cloud workloads.We further evaluate the efficiency of our proposed model in


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Figure 6: Latency-wise prediction accuracy formemory workloads.

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Figure 7: Prediction of CPU intensive workloads.

forecasting memory-intensive workloads of different latencysensitivity levels. Figure 6 depicts the estimation results ofour proposed RVLBPNN model in terms of their predictionaccuracy whilst predicting memory-intensive workloads ofdifferent latency sensitivity levels as described earlier inSection 4. It can be observed from Figure 6 that less latencysensitive memory workloads exhibit better predictability,with the prediction accuracy being 66.17% for level 3 work-loads and 77.48% for level 0 workloads, respectively.

6.2.2. CPU Workloads Prediction. Similar to the memory-intensive workloads, the experiments are repeated for theCPU intensive workloads from the dataset. Figure 7 depictsthe estimation results of RVLBPNN, HMM, and NBC whilstpredicting the CPU intensive workloads. The average pre-diction accuracy of NBC, HMM, and RVLBPNN models is49.87%, 46.36%, and 52.70%, respectively, whilst predictingCPU intensive workloads, as shown in Figure 8. It can beobserved that RVLBPNN exhibits better prediction accuracythan both HMM and NBCmodels by a margin of around 3%and 6%, respectively.

We further evaluated the efficiency of our proposedprediction model in predicting the CPU intensive workloadsof different latency levels. Figure 9 depicts the estimationresults of our proposed RVLBPNN model whilst predictingthe CPU intensive workloads of different latency sensitivitylevels. We observe a similar trend of prediction accuracy

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Figure 8: Prediction accuracy for CPU intensive workloads.

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Figure 9: Latency-wise prediction accuracy for CPU workloads.

between both memory and CPU workloads of differentlatency sensitivity levels. Again CPU intensive workloads ofless latency levels are exhibiting better predictability, with theaccuracy being 66.08% for level 3 workloads and 75.90% forlevel 0 workloads. This leads us to infer that least latencysensitivity level workloads exhibit a better rate of predictionaccuracy for both CPU and memory-intensive workloads.

6.2.3. Interpretation and Discussion. From the experimentresults, it is clearly evident that our proposed RVLBPNNmodel demonstrates better prediction accuracy than bothHMM and NBC models by a considerable margin. Ourproposed model outperforms the other two models whilstpredicting both the CPU intensive and memory-intensiveworkloads. Meanwhile, we also observe that increasing levelsof latency sensitivity of both CPU and memory-intensiveworkloads impose increasing error margin in the predictionresults. Lower level of latency sensitivity exhibits betterpredictability. Since the majority of the Cloud workloads areof lower latency sensitivity levels, our proposed predictionmodel can accurately predict the trend ofmost of the arrivingworkloads. An increased level of intrinsic similarity amongthe arriving workloads facilitates a better learning rate ofthe neurons in the RVLBPNN model, which results in anincreased prediction accuracy. From the experiments, wepostulate that workloads should be treaded uniquely with


respect to their computational demand latency sensitivity anduser requirements for achieving a reliable level of predictionaccuracy. Furthermore, workload prediction analytics canbe benefitted with better accuracy when the workloads areanalyzed at the task level rather than at the job level.

7. Conclusion

Green computing has turned out to be one of the importantcharacteristics for achieving sustainable smart world in thefuture. Resource management by the way of predictingthe expected workloads facilitates optimum scaling of theserver resources, reducing the presence of idle resources andallocating appropriate levels of server resources to executethe user requests. The reliability and accuracy levels of suchprediction techniques directly impacts important decisionmaking in large-scale Cloud datacentre environments. In thispaper, we propose a novel workload prediction model forthe purpose of predicting the future workloads in Clouddatacentres. Our proposed novel workload predictionmodel,called RVLBPNN, is based on BP Neural Network algorithmand predicts the future workloads by the way of exploitingthe intrinsic relationships among the arriving workloads.Theexperimental results indicate that the proposed RVLBPNNmodel achieves better precision and efficiency than theHMM-based and NBC-based prediction techniques. As afuture work, we plan to explore the possibilities of furtherimproving the prediction accuracy of our proposed approach.For instance, incorporating the periodicity effects of theworkload behavior into RVLBPNN can further enhance theprediction accuracy.Meanwhile, investigating the efficienciesof our novel prediction method in predicting the anticipatedworkloads in similar distributed environments will be one ofour future research directions.

Competing Interests

The authors declare that there is no conflict of interests.

Acknowledgments

This work was partially supported by the National NaturalScience Foundation of China under Grants nos. 61502209and 61502207 and the Natural Science Foundation of JiangsuProvince under Grant no. BK20130528.

References

[1] H. Al-Aqrabi, L. Liu, R. Hill, and N. Antonopoulos, “Cloud BI:future of business intelligence in the cloud,” Journal of Computerand System Sciences, vol. 81, no. 1, pp. 85–96, 2015.

[2] T. V. T. Duy, Y. Sato, and Y. Inoguchi, “Performance evaluationof a green scheduling algorithm for energy savings in cloudcomputing,” inProceedings of the IEEE International Symposiumon Parallel & Distributed Processing, Workshops and Phd Forum(IPDPSW ’10), pp. 1–8, Atlanta, Ga, USA, April 2010.

[3] L. Ceuppens, A. Sardella, and D. Kharitonov, “Power savingstrategies and technologies in network equipment opportu-nities and challenges, risk and rewards,” in Proceedings of

the International Symposium on Applications and the Internet(SAINT ’08), pp. 381–384, August 2008.

[4] J. Li, B. Li, T. Wo et al., “CyberGuarder: a virtualization secu-rity assurance architecture for green cloud computing,” FutureGeneration Computer Systems, vol. 28, no. 2, pp. 379–390, 2012.

[5] J. Panneerselvam, L. Liu, N. Antonopoulos, and Y. Bo, “Work-load analysis for the scope of user demand prediction modelevaluations in cloud environments,” in Proceedings of the 7thIEEE/ACM International Conference on Utility and Cloud Com-puting (UCC ’14), pp. 883–889, December 2014.

[6] Z. Wan, “Sub-millisecond level latency sensitive cloud com-puting infrastructure,” in Proceedings of the 2010 InternationalCongress on Ultra Modern Telecommunications and ControlSystems and Workshops (ICUMT ’10), pp. 1194–1197, Moscow,Russia, October 2010.

[7] H. Zhang, G. Jiang, K. Yoshihira, H. Chen, and A. Saxena,“Intelligent workload factoring for a hybrid cloud computingmodel,” in Proceedings of the Congress on Services—I (SERVICES’09), pp. 701–708, 2009.

[8] C. Glasner and J. Volkert, “Adaps—a three-phase adaptiveprediction system for the run-time of jobs based on userbehaviour,” Journal of Computer and System Sciences, vol. 77, no.2, pp. 244–261, 2011.

[9] C. A. L. Fehling, Frank, Retter et al., “CloudComputingPat-terns2014,” 2014.

[10] J. Wang, G. Jia, A. Li, G. Han, and L. Shu, “Behavior awaredata placement for improving cache line level locality in cloudcomputing,” Journal of Internet Technology, vol. 16, no. 4, pp.705–716, 2015.

[11] G. Han,W. Que, G. Jia, and L. Shu, “An efficient virtual machineconsolidation scheme for multimedia cloud computing,” Sen-sors, vol. 16, no. 2, article 246, 2016.

[12] S. Mahambre, P. Kulkarni, U. Bellur, G. Chafle, and D. Desh-pande, “Workload characterization for capacity planning andperformance management in IaaS cloud,” in Proceedings ofthe 1st IEEE International Conference on Cloud Computingfor Emerging Markets (CCEM ’12), pp. 1–7, Bangalore, India,October 2012.

[13] A. Khan, X. Yan, S. Tao, and N. Anerousis, “Workload charac-terization and prediction in the cloud: a multiple time seriesapproach,” in Proceedings of the IEEE Network Operations andManagement Symposium (NOMS ’12), pp. 1287–1294, IEEE,Maui, Hawaii, USA, April 2012.

[14] A.K.Mishra, J. L.Hellerstein,W.Cirne, andC.R.Das, “Towardscharacterizing cloud backend workloads: insights from Googlecompute clusters,” ACM SIGMETRICS Performance EvaluationReview, vol. 37, no. 4, pp. 34–41, 2010.

[15] P. A. Dinda and D. R. O’Hallaron, “Host load prediction usinglinear models,” Cluster Computing, vol. 3, no. 4, pp. 265–280,2000.

[16] S. Di, D. Kondo, and W. Cirne, “Google hostload predictionbased on Bayesian model with optimized feature combination,”Journal of Parallel and Distributed Computing, vol. 74, no. 1, pp.1820–1832, 2014.

[17] I. S.Moreno, P. Garraghan, P. Townend, and J. Xu, “An approachfor characterizing workloads in google cloud to derive realisticresource utilization models,” in Proceedings of the IEEE 7thInternational Symposium on Service-Oriented System Engineer-ing (SOSE ’13), pp. 49–60, IEEE, Redwood City, Calif, USA,March 2013.

[18] N. Roy, A. Dubey, and A. Gokhale, “Efficient autoscaling inthe cloud using predictive models for workload forecasting,” in


Proceedings of the IEEE 4th International Conference on CloudComputing (CLOUD ’11), pp. 500–507, Washington, DC, USA,July 2011.

[19] Z. Wan, “Cloud Computing infrastructure for latency sensitiveapplications,” in Proceedings of the IEEE 12th InternationalConference on Communication Technology (ICCT ’10), pp. 1399–1402, November 2010.

[20] M. S. Bali and S. Khurana, “Effect of latency on network and enduser domains in cloud computing,” in Proceedings of the 2013International Conference on Green Computing, Communicationand Conservation of Energy (ICGCE ’13), pp. 777–782, Chennai,India, December 2013.

[21] Z.Wan, P.Wang, J. Liu, andW. Tang, “Power-aware cloud com-puting infrastructure for latency-sensitive internet-of-thingsservices,” in Proceedings of the UKSim 15th International Con-ference on Computer Modelling and Simulation (UKSim ’13), pp.617–621, April 2013.

[22] C. Reiss, J. Wilkes, and J. L. Hellerstein, “Google cluster-usagetraces: format + schema,” Tech. Rep., Google Inc., MountainView, Calif, USA, 2011.

[23] Google, “GoogleClusterDataV1,” 2011, https://github.com/goo-gle/cluster-data/blob/master/ClusterData2011 2.md.

[24] J. Panneerselvam, L. Liu, N. Antonopoulos, and M. Trovati,“Latency-aware empirical analysis of the workloads for reduc-ing excess energy consumptions at cloud datacentres,” in Pro-ceedings of the IEEE 11th Symposium on Service-Oriented SystemEngineering (SOSE ’16), pp. 62–70, Oxford, UK, March 2016.

[25] Z.Uykan, C.Guzelis, andH.N.Koivo, “Analysis of input-outputclustering for determining centers of RBFN,” IEEE Transactionson Neural Networks, vol. 11, no. 4, pp. 851–858, 2000.

[26] X. Sun, Z. Yang, and Z. Wang, “The application of BP neutralnetwork optimized by genetic algorithm in transportation datafusion,” in Proceedings of the IEEE 2nd International Conferenceon Advanced Computer Control (ICACC ’10), pp. 560–563,Shenyang, China, March 2010.

[27] W. C. Wang, BP Neural Network and Application in AutomobileEngineering, BeiJing Institute of Technology University, 1998.

[28] Z. Li, Q. Lei, X. Kouying, and Z. Xinyan, “A novel BP neural net-work model for traffic prediction of next generation network,”in Proceedings of the 5th International Conference on NaturalComputation (ICNC ’09), pp. 32–38, Tianjin, China, August2009.

[29] M. T. Hagan, H. B. Demuth, and M. Beale, Neural NetworkDesign, PWS Publishing, Boston, Mass, USA, 1996.

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