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Dive into the research topics where Palden Lama is active.

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Featured researches published by Palden Lama.


international conference on autonomic computing | 2012

AROMA: automated resource allocation and configuration of mapreduce environment in the cloud

Palden Lama; Xiaobo Zhou

Distributed data processing framework MapReduce is increasingly deployed in Clouds to leverage the pay-per-usage cloud computing model. Popular Hadoop MapReduce environment expects that end users determine the type and amount of Cloud resources for reservation as well as the configuration of Hadoop parameters. However, such resource reservation and job provisioning decisions require in-depth knowledge of system internals and laborious but often ineffective parameter tuning. We propose and develop AROMA, a system that automates the allocation of heterogeneous Cloud resources and configuration of Hadoop parameters for achieving quality of service goals while minimizing the incurred cost. It addresses the significant challenge of provisioning ad-hoc jobs that have performance deadlines in Clouds through a novel two-phase machine learning and optimization framework. Its technical core is a support vector machine based performance model that enables the integration of various aspects of resource provisioning and auto-configuration of Hadoop jobs. It adapts to ad-hoc jobs by robustly matching their resource utilization signature with previously executed jobs and making provisioning decisions accordingly. We implement AROMA as an automated job provisioning system for Hadoop MapReduce hosted in virtualized HP ProLiant blade servers. Experimental results show AROMAs effectiveness in providing performance guarantee of diverse Hadoop benchmark jobs while minimizing the cost of Cloud resource usage.


modeling, analysis, and simulation on computer and telecommunication systems | 2010

Autonomic Provisioning with Self-Adaptive Neural Fuzzy Control for End-to-end Delay Guarantee

Palden Lama; Xiaobo Zhou

Autonomic server provisioning for performance assurance is a critical issue in data centers. It is important but challenging to guarantee an important performance metric, percentile-based end-to-end delay of requests flowing through a virtualized multi-tier server cluster. It is mainly due to dynamically varying workload and the lack of an accurate system performance model. In this paper, we propose a novel autonomic server allocation approach based on a model-independent and self-adaptive neural fuzzy control. There are model-independent fuzzy controllers that utilize heuristic knowledge in the form of rule base for performance assurance. Those controllers are designed manually on trial and error basis, often not effective in the face of highly dynamic workloads. We design the neural fuzzy controller as a hybrid of control theoretical and machine learning techniques. It is capable of self-constructing its structure and adapting its parameters through fast online learning. Unlike other supervised machine learning techniques, it does not require off-line training. We further enhance the neural fuzzy controller to compensate for the effect of server switching delays. Extensive simulations demonstrate the effectiveness of our new approach in achieving the percentile-based end-to-end delay guarantees. Compared to a rule-based fuzzy controller enabled server allocation approach, the new approach delivers superior performance in the face of highly dynamic workloads. It is robust to workload variation, change in delay target and server switching delays.


IEEE Transactions on Parallel and Distributed Systems | 2012

Efficient Server Provisioning with Control for End-to-End Response Time Guarantee on Multitier Clusters

Palden Lama; Xiaobo Zhou

Dynamic virtual server provisioning is critical to quality-of-service assurance for multitier Internet applications. In this paper, we address three important challenging problems. First, we propose an efficient server provisioning approach on multitier clusters based on an end-to-end resource allocation optimization model. It is to minimize the number of virtual servers allocated to the system while the average end-to-end response time guarantee is satisfied. Second, we design a model-independent fuzzy controller for bounding an important performance metric, the 90th-percentile response time of requests flowing through the multitier architecture. Third, to compensate for the latency due to the dynamic addition of virtual servers, we design a self-tuning component that adaptively adjusts the output scaling factor of the fuzzy controller according to the transient behavior of the end-to-end response time. Extensive simulation results, using two representative customer behavior models in a typical three-tier web cluster, demonstrate that the provisioning approach is able to significantly reduce the number of virtual servers allocated for the performance guarantee compared to an existing representative approach. The approach integrated with the model-independent self-tuning fuzzy controller can efficiently assure the average and the 90th-percentile end-to-end response time guarantees on multitier clusters.


dependable systems and networks | 2012

NINEPIN: Non-invasive and energy efficient performance isolation in virtualized servers

Palden Lama; Xiaobo Zhou

A virtualized data center faces important but challenging issue of performance isolation among heterogeneous customer applications. Performance interference resulting from the contention of shared resources among co-located virtual servers has significant impact on the dependability of application QoS. We propose and develop NINEPIN, a non-invasive and energy efficient performance isolation mechanism that mitigates performance interference among heterogeneous applications hosted in virtualized servers. It is capable of increasing data center utility. Its novel hierarchical control framework aligns performance isolation goals with the incentive to regulate the system towards optimal operating conditions. The framework combines machine learning based self-adaptive modeling of performance interference and energy consumption, utility optimization based performance targeting and a robust model predictive control based target tracking. We implement NINEPIN on a virtualized HP ProLiant blade server hosting SPEC CPU2006 and RUBiS benchmark applications. Experimental results demonstrate that NINEPIN outperforms a representative performance isolation approach, Q-Clouds, improving the overall system utility and reducing energy consumption.


international workshop on quality of service | 2011

PERFUME: power and performance guarantee with fuzzy MIMO control in virtualized servers

Palden Lama; Xiaobo Zhou

It is important but challenging to assure the performance of multi-tier Internet applications with the power consumption cap of virtualized server clusters mainly due to system complexity of shared infrastructure and dynamic and bursty nature of workloads. This paper presents PERFUME, a system that simultaneously guarantees power and performance targets with flexible tradeoffs while assuring control accuracy and system stability. Based on the proposed fuzzy MIMO control technique, it accurately controls both the throughput and percentile-based response time of multi-tier applications due to its novel fuzzy modeling that integrates strengths of fuzzy logic, MIMO control and artificial neural network. It is self-adaptive to highly dynamic and bursty workloads due to online learning of control model parameters using a computationally efficient weighted recursive least-squares method. We implement PERFUME in a testbed of virtualized blade servers hosting two multi-tier RUBiS applications. Experimental results demonstrate its control accuracy, system stability, flexibility in selecting tradeoffs between conflicting targets and robustness against highly dynamic variation and burstiness in workloads. It outperforms a representative utility based approach in providing guarantee of the system throughput, percentile-based response time and power budget in the face of highly dynamic and bursty workloads.


ACM Transactions on Autonomous and Adaptive Systems | 2013

Autonomic Provisioning with Self-Adaptive Neural Fuzzy Control for Percentile-Based Delay Guarantee

Palden Lama; Xiaobo Zhou

Autonomic server provisioning for performance assurance is a critical issue in Internet services. It is challenging to guarantee that requests flowing through a multi-tier system will experience an acceptable distribution of delays. The difficulty is mainly due to highly dynamic workloads, the complexity of underlying computer systems, and the lack of accurate performance models. We propose a novel autonomic server provisioning approach based on a model-independent self-adaptive Neural Fuzzy Control (NFC). Existing model-independent fuzzy controllers are designed manually on a trial-and-error basis, and are often ineffective in the face of highly dynamic workloads. NFC is a hybrid of control-theoretical and machine learning techniques. It is capable of self-constructing its structure and adapting its parameters through fast online learning. We further enhance NFC to compensate for the effect of server switching delays. Extensive simulations demonstrate that, compared to a rule-based fuzzy controller and a Proportional-Integral controller, the NFC-based approach delivers superior performance assurance in the face of highly dynamic workloads. It is robust to variation in workload intensity, characteristics, delay target, and server switching delays. We demonstrate the feasibility and performance of the NFC-based approach with a testbed implementation in virtualized blade servers hosting a multi-tier online auction benchmark.


international workshop on quality of service | 2013

Autonomic performance and power control for co-located Web applications on virtualized servers

Palden Lama; Yanfei Guo; Xiaobo Zhou

In a data center, various components of Web applications co-located on virtualized servers exhibit complex time-varying interactions and interference. It has a significant impact on the user perceived performance and power consumption of the underlying system. We propose and develop APPLEware, an autonomic middleware for joint performance and power control of co-located Web applications. It features a distributed control structure that provides performance assurance and energy efficiency for large complex systems. It applies machine learning based self-adaptive modeling to capture the complex and time-varying relationship between the application performance and allocation of resources to various application components, in the presence of highly dynamic and bursty workloads and inter-application performance interference. The distributed controllers perform coordinated resource allocation to meet the service level agreements of applications in an agile and energy-efficient manner. Experimental results based on a testbed implementation with benchmark applications demonstrate APPLEwares effectiveness and energy efficiency.


international parallel and distributed processing symposium | 2012

Automated and Agile Server Parameter Tuning with Learning and Control

Yanfei Guo; Palden Lama; Xiaobo Zhou

Server parameter tuning in virtualized data centers is crucial to performance and availability of hosted Internet applications. It is challenging due to high dynamics and burstiness of workloads, multi-tier service architecture, and virtualized server infrastructure. In this paper, we investigate automated and agile server parameter tuning for maximizing effective throughput of multi-tier Internet applications. A recent study proposed a reinforcement learning based server parameter tuning approach for minimizing average response time of multi-tier applications. Reinforcement learning is a decision making process determining the parameter tuning direction based on trial-and-error, instead of quantitative values for agile parameter tuning. It relies on a predefined adjustment value for each tuning action. However it is nontrivial or even infeasible to find an optimal value under highly dynamic and bursty workloads. We design a neural fuzzy control based approach that combines the strengths of fast online learning and self-adaptive ness of neural networks and fuzzy control. Due to the model independence, it is robust to highly dynamic and bursty workloads. It is agile in server parameter tuning due to its quantitative control outputs. We implement the new approach on a test bed of virtualized HP Pro Liant blade servers hosting RUBiS benchmark applications. Experimental results demonstrate that the new approach significantly outperforms the reinforcement learning based approach for both improving effective system throughput and minimizing average response time.


international parallel and distributed processing symposium | 2013

V-Cache: Towards Flexible Resource Provisioning for Multi-tier Applications in IaaS Clouds

Yanfei Guo; Palden Lama; Jia Rao; Xiaobo Zhou

Although the resource elasticity offered by Infrastructure-as-a-Service (IaaS) clouds opens up opportunities for elastic application performance, it also poses challenges to application management. Cluster applications, such as multi-tier websites, further complicates the management requiring not only accurate capacity planning but also proper partitioning of the resources into a number of virtual machines. Instead of burdening cloud users with complex management, we move the task of determining the optimal resource configuration for cluster applications to cloud providers. We find that a structural reorganization of multi-tier websites, by adding a caching tier which runs on resources debited from the original resource budget, significantly boosts application performance and reduces resource usage. We propose V-Cache, a machine learning based approach to flexible provisioning of resources for multi-tier applications in clouds. V-Cache transparently places a caching proxy in front of the application. It uses a genetic algorithm to identify the incoming requests that benefit most from caching and dynamically resizes the cache space to accommodate these requests. We develop a reinforcement learning algorithm to optimally allocate the remaining capacity to other tiers. We have implemented V-Cache on a VMware-based cloud testbed. Experiment results with the RUBiS and WikiBench benchmarks show that V-Cache outperforms a representative capacity management scheme and a cloud-cache based resource provisioning approach by at least 15% in performance, and achieves at least 11% and 21% savings on CPU and memory resources, respectively.


international workshop on quality of service | 2009

Efficient server provisioning with end-to-end delay guarantee on multi-tier clusters

Palden Lama; Xiaobo Zhou

Dynamic server provisioning is critical to quality-of-service assurance for multi-tier Internet applications. In this paper, we address three important and challenging problems. First, we propose an efficient server provisioning approach on multi-tier clusters based on an end-to-end resource allocation optimization model. It is to minimize the number of servers allocated to the system while the average end-to-end delay guarantee is satisfied. Second, we design a model-independent fuzzy controller for bounding an important performance metric, the 90th-percentile delay of requests flowing through the multi-tier architecture. Third, to compensate for the latency due to the dynamic addition of servers, we design a self-tuning component that adaptively adjusts the output scaling factor of the fuzzy controller according to the transient behavior of the end-to-end delay. Extensive simulation results, using one representative customer behavior model in a typical three-tier web cluster, demonstrate that the provisioning approach is able to significantly reduce the server utilization compared to an existing representative approach. The approach integrated with the model-independent self-tuning fuzzy controller can efficiently assure the average and the 90th-percentile end-to-end delay guarantees on multi-tier server clusters.

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Xiaobo Zhou

University of Colorado Colorado Springs

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Yanfei Guo

University of Colorado Colorado Springs

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Dazhao Cheng

University of Colorado Colorado Springs

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Eric Pettijohn

University of Colorado Colorado Springs

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Jia Rao

University of Colorado Colorado Springs

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