Tianyu Wo

EnaCloud: An Energy-Saving Application Live Placement Approach for Cloud Computing Environments

With the increasing prevalence of large scale cloud computing environments, how to place requested applications into available computing servers regarding to energy consumption has become an essential research problem, but existing application placement approaches are still not effective for live applications with dynamic characters. In this paper, we proposed a novel approach named EnaCloud, which enables application live placement dynamically with consideration of energy efficiency in a cloud platform. In EnaCloud, we use a Virtual Machine to encapsulate the application, which supports applications scheduling and live migration to minimize the number of running machines, so as to save energy. Specially, the application placement is abstracted as a bin packing problem, and an energy-aware heuristic algorithm is proposed to get an appropriate solution. In addition, an over-provision approach is presented to deal with the varying resource demands of applications. Our approach has been successfully implemented as useful components and fundamental services in the iVIC platform. Finally, we evaluate our approach by comprehensive experiments based on virtual machine monitor Xen and the results show that it is feasible.

A VMM-Based System Call Interposition Framework for Program Monitoring

System call interposition is a powerful method for regulating and monitoring program behavior. A wide variety of security tools have been developed which use this technique. However, traditional system call interposition techniques are vulnerable to kernel attacks and have some limitations on effectiveness and transparency. In this paper, we propose a novel approach named VSyscall, which leverages virtualization technology to enable system call interposition outside the operating system. A system call correlating method is proposed to identify the coherent system calls belonging to the same process from the system call sequence. We have developed a prototype of VSyscall and implemented it in two mainstream virtual machine monitors, Qemu and KVM, respectively. We also evaluate the effectiveness and performance overhead of our approach by comprehensive experiments. The results show that VSyscall achieves effectiveness with a small overhead, and our experiments with six real-world applications indicate its practicality.

An Efficient Resource Management System for On-Line Virtual Cluster Provision

As a prevalent paradigm for flexible, scalable and on-demand provisions of computing services, Cloud Computing can be an alternative platform for scientific computing. In this paper, we propose an efficient resource management system for on-line virtual clusters provision, aiming to provide immediately-available virtual clusters for academic users. Particularly, we investigated two crucial problems: efficient VM image management and intelligent resource mapping, either of them has remarkable impact on the performance of the system. VM image management includes image preparation and local image management on physical resources. A resource mapping refers to a mapping from user’s resource constraints to specific physical resources. We explore how to simplify VM image management and reduce image preparation overhead by the multicast file transferring and image caching/reusing. Additionally, the Load-Aware Mapping, a novel resource mapping strategy, is proposed in order to further reduce deploying overhead and make efficient use of resources. The strategy takes account of both image cache and VM load distribution information. System evaluation is conducted through various real stress workloads, and results show that our approaches are effective comparing to other common solutions.

HyperMIP: Hypervisor Controlled Mobile IP for Virtual Machine Live Migration across Networks

Live migration provides transparent load-balancing and fault-tolerant mechanism for applications. When a Virtual Machine migrates among hosts residing in two networks, the network attachment point of the Virtual Machine is also changed, thus the Virtual Machine will suffer from IP mobility problem after migration. This paper proposes an approach called Hypervisor controlled Mobile IP to support live migration of Virtual Machine across networks, which enables virtual machine live migration over distributed computing resources. Since Hypervisor is capable of predicting exact time and destination host of Virtual Machine migration, our approach not only can improve migration performance but also reduce the network restoration latency. Some comprehensive experiments have been conducted and the results show that the HyperMIP brings negligible overhead to network performance of Virtual Machines. The network restoration time of HyperMIP supported migration is about only 3 second. HyperMIP is a promising essential component to provide reliability and fault tolerant for network application running in Virtual Machine.

CyberLiveApp: A secure sharing and migration approach for live virtual desktop applications in a cloud environment

Abstract In recent years, we have witnessed the rapid advent of cloud computing, in which remote software is delivered as a service and accessed by users using a thin client over the Internet. In particular, a traditional desktop application can execute in the remote virtual machines of clouds without re-architecture and provide a personal desktop experience to users through remote display technologies. However, existing cloud desktop applications have isolated environments with virtual machines (VMs), which cannot adequately support application-oriented collaborations between multiple users and VMs. In this paper, we propose a flexible collaboration approach, named CyberLiveApp, to enable live virtual desktop application sharing, based on a cloud and virtualization infrastructure. CyberLiveApp supports secure application sharing and on-demand migration among multiple users or equipment. To support VM desktop sharing among multiple users, we develop a secure access mechanism to distinguish their view privileges, in which window operation events are tracked to compute hidden areas of windows in real time. A proxy-based window filtering mechanism is also proposed to deliver desktops to different users. To achieve the goals of live application sharing and migration between VMs, a presentation redirection approach based on VNC protocol and a VM cloning service based on the Libvirt interface are used. These approaches have been preliminary evaluated on an extended MetaVNC. Results of evaluations have verified that these approaches are effective and useful.

VMScatter: migrate virtual machines to many hosts

Live virtual machine migration is a technique often used to migrate an entire OS with running applications in a non-disruptive fashion. Prior works concerned with one-to-one live migration with many techniques have been proposed such as pre-copy, post-copy and log/replay. In contrast, we propose VMScatter, a one-to-many migration method to migrate virtual machines from one to many other hosts simultaneously. First, by merging the identical pages within or across virtual machines, VMScatter multicasts only a single copy of these pages to associated target hosts for avoiding redundant transmission. This is impactful practically when the same OS and similar applications running in the virtual machines where there are plenty of identical pages. Second, we introduce a novel grouping algorithm to decide the placement of virtual machines, distinguished from the previous schedule algorithms which focus on the workload for load balance or power saving, we also focus on network traffic, which is a critical metric in data-intensive data centers. Third, we schedule the multicast sequence of packets to reduce the network overhead introduced by joining or quitting the multicast groups of target hosts. Compared to traditional live migration technique in QEMU/KVM, VMScatter reduces 74.2% of the total transferred data, 69.1% of the total migration time and achieves the network traffic reduction from 50.1% to 70.3%.

CROWN: A service grid middleware with trust management mechanism

Based on a proposed Web service-based grid architecture, a service grid middleware system called CROWN is designed in this paper. As the two kernel points of the middleware, the overlay-based distributed grid resource management mechanism is proposed, and the policy-based distributed access control mechanism with the capability of automatic negotiation of the access control policy and trust management and negotiation is also discussed in this paper. Experience of CROWN testbed deployment and application development shows that the middleware can support the typical scenarios such as computing-intensive applications, data-intensive applications and mass information processing applications.

A Virtualization-Based SaaS Enabling Architecture for Cloud Computing

With the increasing prevalence of large scale cloud computing environment, researchers has draw more attention about how to provide software as a service through the internet. In this paper, a novel approach named vSaaS is proposed in iVIC platform, which is the virtual computing environment for HaaS and SaaS applications. The aim of this approach is to provide the software as a service from a cloud computing environment over the Internet; users are able to access different software transparently with no limitation on the client operation system or device capability. OS-level virtualization and remote display technologies are employed in the vSaaS system. Benefit from above technologies, massive exist legacy software could be easily adopted without any recompilation and redevelopment work. Software can be dynamic streaming deployed in the back-end resource pool in a dynamic streaming way. Finally, comprehensive experiments are conducted to demonstrate the feasibility and performance of the vSaaS implementation.

MultiLanes: Providing Virtualized Storage for OS-Level Virtualization on Manycores

OS-level virtualization is often used for server consolidation in data centers because of its high efficiency. However, the sharing of storage stack services among the colocated containers incurs contention on shared kernel data structures and locks within I/O stack, leading to severe performance degradation on manycore platforms incorporating fast storage technologies (e.g., SSDs based on nonvolatile memories). This article presents MultiLanes, a virtualized storage system for OS-level virtualization on manycores. MultiLanes builds an isolated I/O stack on top of a virtualized storage device for each container to eliminate contention on kernel data structures and locks between them, thus scaling them to manycores. Meanwhile, we propose a set of techniques to tune the overhead induced by storage-device virtualization to be negligible, and to scale the virtualized devices to manycores on the host, which itself scales poorly. To reduce the contention within each single container, we further propose SFS, which runs multiple file-system instances through the proposed virtualized storage devices, distributes all files under each directory among the underlying file-system instances, then stacks a unified namespace on top of them. The evaluation of our prototype system built for Linux container (LXC) on a 32-core machine with both a RAM disk and a modern flash-based SSD demonstrates that MultiLanes scales much better than Linux in micro- and macro-benchmarks, bringing significant performance improvements, and that MultiLanes with SFS can further reduce the contention within each single container.

iROW: An Efficient Live Snapshot System for Virtual Machine Disk

The high-availiablity of mission-critical data and services hosted in a virtual machine (VM) is one of the top concerns in a cloud computing environment. The live disk snapshot is an emerging technology to save the whole state and the data of a VM at a specific point of time, and be used for quick disaster recovery. However, the existing VM disk snapshot systems suffer from long operation time and I/O performance degradation problems during snapshots creating and managing, and thereby affecting the performance of the VM and its services. To address such issues, we designed an efficient VM disk snapshot system, named iROW (improved Redirect-on-Write). In iROW, a bitmap based light-weight index scheme is adopted to replace the existing multi-level index tree structure to reduce query cost. Additionally, through a combination of Redirect-on-Write (ROW) and Copy-on-Demand (COD) schema to avoid extra copy operation on the first write after snapshot with Copy-on-Write (COW) schema, and the file fragmentation problem caused by ROW snapshot after long-term using. Finally, iROW gives a unified disk space allocation function by the host machines file system. We have implemented iROW in qemu-kvm 0.12.5 and conducted some experiments. The implementation of iROW completely obey the interfaces of the block device driver in QEMU, so it is transparent to the upper system or applications and original disk image formats can be also supported. The experimental results show that iROW has obvious performance advantages in snapshot creating and management operations. Compared with the existing qcow2 disk image in KVM, when the VM disk size is 50GB, and the cluster size is 64KB (the default cluster size of qcow2), the snapshot creation and rollback time is only about 6% and 3% of original qcow2s. With the increasing of the VM disk size, iROW has more performance advantages on snapshot creation and rollback operations. In addition, the I/O performance of iROW is better than qcow2. When the cluster size is 64 KB, typically the iROWs performance loss is 10% less than qcow2s, and its first write performance after snapshot creation is about 250% of qcow2s.