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6 results
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ItemCreating Efficient Execution Platforms with V(irtualized) Services(Georgia Institute of Technology, 2008) Seshasayee, Balasubramanian ; Schwan, KarstenVirtualization is creating new opportunities for innovative uses of middleware technologies. In this paper, we present such opportunities for mobile or pervasive environments, where virtualization efforts face challenges that include the diversity of platforms and devices present in these domains, dynamic device and resource behaviors, and the efficient use and sharing of such resources. Specifically, we leverage middleware to significantly extend virtualization technologies in terms of their efficient support for resource sharing in the presence of diversity, dynamics, and mobility. The outcome is what we term the Virtualized Services (VServices) approach to representing and using devices and resources. VServices extend the virtual device interfaces used in existing virtualization infrastructures to go beyond sharing physical devices among multiple virtual machines, to also sharing logical entities that internally use middleware to provide new services to end user applications. By using and sharing the higher level VServices abstractions instead of physical devices, opportunities are created (i) to optimize the implementations of certain services without requiring changes to VM implementations, (ii) to enhance device functionalities by combining software service implementations with the physical devices being used, again without changing the basic nature of VM-device interactions, and (iii) to emulate devices whose physical realizations may be remote or non-existent. Experimental evaluations conducted on an implementation of these concepts in the Xen virtualization infrastructure exhibit up to 50% improvements in latency as well as improved performance scalability, when compared to current Xen implementations of such devices. This paper also describes practical realization of device enhancements using VServices.
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ItemVMedia: Enhanced Multimedia Services in Virtualized Systems(Georgia Institute of Technology, 2007) Raj, Himanshu ; Seshasayee, Balasubramanian ; Schwan, KarstenThis paper presents the VMedia multimedia virtualization framework, for sharing media devices among multiple virtual machines (VMs). The framework provides logical media devices to virtual machines. These devices are exported via a well defined, higher level, multimedia access interface to the applications and operating system running in a virtual machine. By using semantically meaningful information, rather than low-level raw data, within the VMedia framework, efficient virtualization solutions can be created for physical devices shared by multiple virtual machines. Experimental results demonstrate that the base cost of virtual device access via VMedia is small compared to native physical device access, and in addition, that these costs scale well with an increasing number of guest VMs. Here, VMedia’s MediaGraph abstraction is a key contributor, since it also allows the framework to support dynamic restructuring, in order to adapt device accesses to changing requirements. Finally, VMedia permits platforms to offer new and enhanced logical device functionality at lower costs than those achievable with alternative solutions.
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ItemEnergy-aware Mobile Service Overlays: Cooperative Dynamic Power Management in Distributed Mobile Systems(Georgia Institute of Technology, 2007) Seshasayee, Balasubramanian ; Nathuji, Ripal ; Schwan, KarstenWith their increasingly powerful computational resources and high-speed wireless communications, future mobile systems will have the ability to run sophisticated applications on collections of cooperative end devices. Mobility, however, requires dynamic management of these platforms' distributed resources, and such management can also be used to meet application quality requirements and prolong application lifetimes, the latter by best using available energy resources. This paper presents energy-aware Mobile Service Overlays (MSOs), a set of mechanisms and associated policies for running mobile applications across multiple, cooperating machines while actively performing power management to extend system usability lifetimes. MSO policies manage energy consumption by (i) allocating application components to available nodes based upon their current energy capacities and resource availabilities, (ii) monitoring for, and responding to changes in energy and resource characteristics, and (iii) dynamically exploiting energy-performance tradeoffs in overprovisioned situations. Coupled with mobility, such cooperation enables multiple mobile platforms to bring their joint resources to bear on complex application tasks, providing significant benefits to application lifetimes and performance. This paper evaluates MSOs on a MANET computing testbed indicate an extension in system lifetime of upto 10% for an example application.
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ItemAutonomic Information Flows(Georgia Institute of Technology, 2005) Schwan, Karsten ; Cooper, Brian F. ; Eisenhauer, Greg S. ; Gavrilovska, Ada ; Wolf, Matthew ; Abbasi, Hasan ; Agarwala, Sandip ; Cai, Zhongtang ; Kumar, Vibhore ; Lofstead, Jay ; Mansour, Mohamed S. ; Seshasayee, Balasubramanian ; Widener, Patrick M. (Patrick McCall)Today's enterprise systems and applications implement functionality that is critical to the ability of society to function. These complex distributed applications, therefore, must meet dynamic criticality objectives even when running on shared heterogeneous and dynamic computational and communication infrastructures. Focusing on the broad class of applications structured as distributed information flows, the premise of our research is that it is difficult, if not impossible, to meet their dynamic service requirements unless these applications exhibit autonomic or self-adjusting behaviors that are `vertically' integrated with underlying distributed systems and hardware. Namely, their autonomic functionality should extend beyond the dynamic load balancing or request routing explored in current web-based software infrastructures to (1) exploit the ability of middleware or systems to be aware of underlying resource availabilities, (2) dynamically and jointly adjust the behaviors of interacting elements of the software stack being used, and even (3) dynamically extend distributed platforms with enterprise functionality (e.g., network-level business rules for data routing and distribution). The resulting vertically integrated systems can meet stringent criticality or performance requirements, reduce potentially conflicting behaviors across applications, middleware, systems, and resources, and prevent breaches of the `performance firewalls' that isolate critical from non-critical applications. This paper uses representative information flow applications to argue the importance of vertical integration for meeting criticality requirements. This is followed by a description of the AutoFlow middleware, which offers methods that drive the control of application services with runtime knowledge of current resource behavior. Finally, we demonstrate the opportunities derived from the additional ability of AutoFlow to enhance such methods by also dynamically extending and controlling the underlying software stack, first to better understand its behavior and second, to dynamically customize it to better meet current criticality requirements.
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ItemEnergy-Efficient Device Scheduling through Contextual Timeouts(Georgia Institute of Technology, 2005) Seshasayee, Balasubramanian ; Schwan, KarstenHandheld and embedded hardware platforms are operating with an increasing number of internal and external devices, potentially increasing energy consumption and more importantly, motivating the need for energy management techniques for peripheral devices. This paper presents a platform-wide, system-level approach to dynamic energy management, termed contextual timeouts. The approach exploits the fact that most current peripheral devices support the ability to switch to a low power mode when not in use and automatically resuming operation upon use. The approach utilizes the energy savings derived from such device suspensions, considering that the device suspend/resume actions themselves consume power and have associated latencies. Contextual timeouts do not require programmer involvement. Instead, dynamic instrumentation is used to automatically capture and monitor the contexts (i.e., the execution points) at which programs make the service requests that cause device usage. From such dynamic monitoring data, system-level algorithms predict future request times and manage devices to best meet program needs under predicted behaviors. Adaptive methods for dynamic workload characterization coupled with runtime techniques for request prediction result in experimentally obtained energy savings of up to 50% over an aggressive timeout-based regime on a Linux-based iPAQ PDA.
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ItemSOAP-binQ: High Performance SOAP with Continuous Quality Management(Georgia Institute of Technology, 2003) Seshasayee, Balasubramanian ; Schwan, Karsten ; Widener, Patrick M. (Patrick McCall)There is substantial interest in using SOAP (Simple Object Access Protocol) in distributed applications' inter-process communications due to its promise of universal interoperability. The utility of SOAP is limited, however, by its inefficient implementation, which represents all invocation parameters in XML, for instance. This paper aims to make SOAP useful for high end or resource-constrained applications. The basic idea is to replace SOAP's XML/Ascii-based parameter representations with binary ones. Using SOAP's WSDL parameter descriptions, XML-based parameters are automatically represented as corresponding structured binary data, which are then used in all client-server communications. Data is up- or down-translated to/from XML form only if and when needed by end points. The resulting SOAP-bin communication protocol exhibits substantially improved performance compared to regular SOAP communications, particularly when used in the internal communications occurring across cooperating client/servers or servers. Gains are particularly evident when the same types of parameters are exchanged repeatedly, examples including transactional applications, remote graphics and visualization, distributed scientific codes. A further improvement to SOAP-bin, termed SOAP-binQ, addresses highly resource-constrained, time-dependent applications like distributed media codes, where scarce communication bandwidth, for example, may prevent end users from interacting in real-time. SOAP-binQ offers additional quality management functions that permit SOAP to reduce parameter sizes dynamically, as and when needed. The methods used in size reduction are provided by end users and/or by applications, thereby enabling domain-specific tradeoffs in quality vs. performance, for example. An adaptive use of SOAP-binQ's quality management techniques presented in this paper significantly reduces the jitter experienced in two sample applications: remote sensing and remote visualization.