Xinda Lu

The hybrid scheduling framework for virtual machine systems

The virtualization technology makes it feasible that multiple guest operating systems run on a single physical machine. It is the virtual machine monitor that dynamically maps the virtual CPU of virtual machines to physical CPUs according to the scheduling strategy. The scheduling strategy in Xen schedules virtual CPUs of a virtual machines asynchronously while guarantees the proportion of the CPU time corresponding to its weight, maximizing the throughput of the system. However, this scheduling strategy may deteriorate the performance when the virtual machine is used to execute the concurrent applications such as parallel programs or multithreaded programs. In this paper, we analyze the CPU scheduling problem in the virtual machine monitor theoretically, and the result is that the asynchronous CPU scheduling strategy will waste considerable physical CPU time when the system workload is the concurrent application. Then, we present a hybrid scheduling framework for the CPU scheduling in the virtual machine monitor. There are two types of virtual machines in the system: the high-throughput type and the concurrent type. The virtual machine can be set as the concurrent type when the majority of its workload is concurrent applications in order to reduce the cost of synchronization. Otherwise, it is set as the high-throughput type as the default. Moreover, we implement the hybrid scheduling framework based on Xen, and we will give a description of our implementation in details. At last, we test the performance of the presented scheduling framework and strategy based on the multi-core platform, and the experiment result indicates that the scheduling framework and strategy is feasible to improve the performance of the virtual machine system.

Automatic Performance Tuning for the Virtualized Cluster System

System virtualization can aggregate the functionality of multiple standalone computer systems into a single hardware computer. It is significant to virtualize the computing nodes with multi-core processors in the cluster system, in order to promote the usage of the hardware while decrease the cost of the power. In the virtualized cluster system, multiple virtual machines are running on a computing node. However, it is a challenging issue to automatically balance the workload in virtual machines on each physical computing node, which is different from the traditional cluster systems load balance. In this paper, we propose a management framework for the virtualized cluster system, and present an automatic performance tuning strategy to balance the workload in the virtualized cluster system. We implement a working prototype of the management framework (VEMan) based on Xen, and test the performance of the tuning strategy on a virtualized heterogeneous cluster system. The experimental result indicates that the management framework and tuning strategy are feasible to improve the performance of the virtualized cluster system.

An economic-based resource management framework in the grid context

The economic mechanism is very suitable for solving the problem of resource management in the grid computing environment, and it can guarantee the interest of participators in the grid with fairness and efficiency. In this paper, we propose an economics-based resource management framework for grid computing, and then we focus on how to determine the price of resources with the economic mechanism. We present a general equilibrium method for general resources and a double auction method for special resources in the grid environment respectively. Simulations are performed and the experimental results indicate that the two methods are effective for corresponding application scenarios.

An Online Scheduling Algorithm for Assigning Jobs in the Computational Grid

The computational grid provides a promising platform for the deployment of various high-performance computing applications. Problem in implementing computational grid environments is how to effectively use various resources in the system, such as CPU cycle, memory, communication network, and data storage. There are many effective heuristic algorithms for scheduling in the computational grid, however most scheduling strategies have no theoretical guarantee at all. In this paper, a cost-based online scheduling algorithm is presented for job assignment in the grid environment with theoretical guarantee. Firstly, a scheduling framework is described, where the grid environment is characterized, and the online job model is defined. Secondly, the cost-based online scheduling algorithm is presented where costs of resources are exponential functions of their loads, and the performance of this algorithm is theoretically analyzed against the performance of the optimal offline algorithm. Finally, we implement the algorithm in the grid simulation environment, and compare the performance of the presented algorithm with the other three algorithms, and experimental results indicate that the cost-based online scheduling algorithm can outperform the other three online algorithms.

A double auction mechanism for resource allocation on grid computing systems

Considering dynamic, heterogeneous and autonomous characteristics of computing resources in grid computing systems and the flexibility and effectivity of economics methods applied to solve the problem of resource management, a double auction mechanism for resource allocation on grid computing systems is presented. Firstly, a market model of double auction is described, in which agents are utilized to represent the computational resource traders in the grid environment and are equipped with the reinforcement learning algorithm. Secondly, a double auction mechanism is presented, where the uniform-price auction is adopted aiming at CPU resources, and the transaction fee can be adjusted flexibly. Finally, the efficiency of the presented double auction mechanism is analyzed through experiments, and experimental results show that the presented mechanism is efficient, and the transaction price varies mildly.

Recent advances in CFD grid application platform

The computational fluid dynamics (CFD) grid application platform provides a grid environment for CFD applications using high performance computing. It adopts service oriented architecture (SOA), is based on IBMs Service Domain, extends and customizes it for CFD applications in several modules, such as service requesting, job scheduling, job management, failure recovery, etc. By defining general CFD application interfaces such as data format, the platform integrates different CFD applications, including mesh generation, domain decomposition and resolvers, to follow the workflow customized by end-users to finish a complete CFD job. Furthermore, CFD application development specifications and packages are provided to facilitate migrating most sequential and parallel CFD applications to the platform. Currently, a prototype system is available online to the public for testing.

Data Aggregation with Multiple Spanning Trees in Wireless Sensor Networks

In wireless sensor networks, the data aggregation is an essential paradigm for routing, through which the multiple data from different sensors can be aggregated into a single data at intermedial nodes enroute, in order to eliminate data redundancy and achieve the goal of saving energy. Some existed medium access protocols and algorithms can effectively prolong the lifetime of the sensor network by determining when each sensor should transmit its data, and when it should sleep. In this paper, we focus on applying multiple spanning trees to organize the data aggregation, which is different from these existed single spanning tree methods. At first, the problem of constructing multiple spanning trees is transformed into a linear programming problem of the data flow network. Based on the solved optimal rate between the two adjacent sensors, the two constructing algorithms of the spanning tree are presented. Experimental results indicate that the method of multiple spanning trees can be of benefit to energy saving for wireless sensor networks, and the corresponding appropriate constructing algorithm can prolong the lifetime of the sensor network.

A Distributed Approach for Resource Pricing in Grid Environments

A distributed group-pricing algorithm is presented for the market-based resource management in the grid context based on quick convergence of centralized algorithms and scalability of distributed algorithms. According to the new algorithm, resources in the system are divided into multiple resource groups according to the degree of price correlation of resources. When the demand and supply of resources in the system changes, each auctioneer in the defined system structure is responsible for adjusting simultaneously the price of one resource group respectively until the excess demand of all resources becomes zero. We test the distributed group-pricing algorithm against the existed distributed algorithm, and analyze the property of the algorithm. Experimental results indicate that an equilibrium can be achieved by the distributed group-pricing algorithm quicker than by the existed distributed algorithm.

A BLP-Based Access Control Mechanism for the Virtual Machine System

The virtual machine system such as Xen provides a security isolation between virtual machines (VM) running on the virtual machine monitor (VMM). With the wide application of the virtualization technology, VMM is expected to not only provide the simple isolation but also provide limited sharing between VMs in a secure manner. In this paper, we present an access control mechanism for the virtual machine system, which is based on the BLP model. We prove that the virtual machine system with the access control mechanism and an initial secure state is a secure system. In addition, we implement a prototype of the access control mechanism for the virtual machine system based on Xen.

Aero-crafts Aerodynamic Simulation and Optimization by Using “CFD-Grid” Based on Service Domain

A novel high performance computational (HPC) framework by using “Computational Grid” technology for aero-crafts aerodynamic simulation and optimization is present. There are three components in this HPC “CFD-Grid” framework: Grid Service module based on IBM Service Domain, general interface standards for CFD codes and CFD codes for application. All those components in the service domain system are named as “Grid Services” independently. The HPC “CFD-Grid” framework can run on various computers with various platforms, through which various CFD codes and computer resources are provided to the designers in the form of services, no matter where those computers are located. Based on this “CFD-Grid” of Shanghai Jiao Tong University supported by China-Grid project, aero-crafts aerodynamic simulation and optimization can be completed. To demonstrate the ability of this “CFD-Grid” HPC framework, aero-craft simulation and optimization cases was described.