Combining high-speed network accesses and powerful computer virtualization, cloud computing provides an elastic and cost-effective service paradigm for the development of resource-hungry new applications as well as the expansion of a broad spectrum of existing applications. Virtualization has become wide spread in modern computers and operating systems; the extensive use of virtual machines (VMs) in a networked cloud environment, however, comes with unprecedented overhead. In this thesis we study the impact of virtualization overhead on real-world systems. First, we present a study on the performance of modern virtualization solutions under DoS attacks. We experiment with the full spectrum of modern virtualization techniques, from paravirtualization, hardware virtualization, to container virtualization, with a comprehensive set of benchmarks. Our results reveal severe vulnerability of modern virtualization. Further, this thesis presents an empirical study on the power consumption of typical virtualization packages while performing network tasks. We find that both Hardware Virtualization and Paravirtualization add considerable energy overhead, affecting both sending and receiving, and a busy virtualized web-server may consume 40% more energy than its non-virtualized counterparts. Next, we focused on cloud network performance instability in the public cloud. Through measurement of real world cloud platforms, we find that network performance degradation and variation phenomena can be prevalent and significant with both TCP and UDP traffic, even within the same data center, and even with a lightly utilized network. Our in-depth measurement and detailed system analysis reveal that the performance variation and degradation are mainly due to the requirements of the CPU in both computation and network communication. Finally, we study the use of virtual machine based clouds to provide infrastructure to support cloud gaming. For each issue we further suggest solutions to resolve performance issues associated with virtualized environments, both at the hypervisor level and, inside a VM, at the operating system level. Our implementation on both large public clouds and our cloud testbed have demonstrated their practicality as well as their effectiveness in improving and stabilizing the energy consumption and performance of virtual machine based clouds.

Advances in Computers carries on a tradition of excellence, presenting detailed coverage of innovations in computer hardware, software, theory, design, and applications. The book provides contributors with a medium in which they can explore their subjects in greater depth and breadth than journal articles typically allow. The articles included in this book will become standard references, with lasting value in this rapidly expanding field. Presents detailed coverage of recent innovations in computer hardware, software, theory, design, and applications Includes in-depth surveys and tutorials on new computer technology pertaining to computing: combinatorial testing, constraint-based testing, and black-box testing Written by well-known authors and researchers in the field Includes extensive bibliographies with most chapters Presents volumes devoted to single themes or subfields of computer science

Networking and machine virtualization play critical roles in the success of modern cloud computing. The energy consumption of physical machines has been carefully examined in the past, including the impact from network traffic. When it comes to virtual machines (VMs) in cloud data centers, it remains unexplored how the highly dynamic traffic affects the energy consumption in virtualized environments. In this thesis, we first present an empirical study on the interplay between energy consumption and network transactions in virtualized environments. Through the real-world measurement on both Xen- and KVM-based platforms, we show that these state-of-the-art designs bring significant overhead on virtualizing network devices and noticeably increase the demand of CPU resources when handling network traffic. Furthermore, the energy consumption varies significantly with traffic allocation strategies and virtual CPU affinity conditions, which was not seen in conventional physical machines. Next, we study the performance and energy efficiency issues when CPU intensive tasks and I/O intensive tasks are co-located inside a VM. A combined effect from device virtualization overhead and VM scheduling latency can cause severe interference in the presence of such hybrid workloads. To this end, we propose Hylics, a novel solution that enables an efficient data traverse path for both I/O and computation operations, and decouples the costly interference. Several important design issues are pinpointed and addressed during our implementation, including efficient intermediate data sharing, network service offloading, and QoS-aware memory usage management. Based on our real-world deployment in KVM, Hylics can improve computation and networking performance with a moderate amount of memory usage. Moreover, this design also sheds new light on optimizing the energy efficiency for virtualized systems.

Research into grid computing has been driven by the need to solve large-scale, increasingly complex problems for scientific applications. Yet the applications of grid computing for business and casual users did not begin to emerge until the development of the concept of cloud computing, fueled by advances in virtualization techniques, coupled with the increased availability of ever-greater Internet bandwidth. The appeal of this new paradigm is mainly based on its simplicity, and the affordable price for seamless access to both computational and storage resources. This timely text/reference introduces the fundamental principles and techniques underlying grids, clouds and virtualization technologies, as well as reviewing the latest research and expected future developments in the field. Readers are guided through the key topics by internationally recognized experts, enabling them to develop their understanding of an area likely to play an ever more significant role in coming years. Topics and features: presents contributions from an international selection of experts in the field; provides a thorough introduction and overview of existing technologies in grids, clouds and virtualization, including a brief history of the field; examines the basic requirements for performance isolation of virtual machines on multi-core servers, analyzing a selection of system virtualization technologies; examines both business and scientific applications of grids and clouds, including their use in the life sciences and for high-performance computing; explores cloud building technologies, architectures for enhancing grid infrastructures with cloud computing, and cloud performance; discusses energy aware grids and clouds, workflows on grids and clouds, and cloud and grid programming models. This useful text will enable interested readers to familiarize themselves with the key topics of grids, clouds and virtualization, and to contribute to new advances in the field. Researchers, undergraduate and graduate students, system designers and programmers, and IT policy makers will all benefit from the material covered.

The purpose of this book is first to study cloud computing concepts, security concern in clouds and data centers, live migration and its importance for cloud computing, the role of firewalls in domains with particular focus on virtual machine (VM) migration and its security concerns. The book then tackles design, implementation of the frameworks and prepares test-beds for testing and evaluating VM migration procedures as well as firewall rule migration. The book demonstrates how cloud computing can produce an effective way of network management, especially from a security perspective.

This book presents the state-of-the-art and breakthrough innovations in design automation for cyber-physical systems.The authors discuss various aspects of cyber-physical systems design, including modeling, co-design, optimization, tools, formal methods, validation, verification, and case studies. Coverage includes a survey of the various existing cyber-physical systems functional design methodologies and related tools will provide the reader unique insights into the conceptual design of cyber-physical systems.