The SPLASH-2 suite of parallel applications has recently been released to facilitate the study of centralized and distributed shared-address-space multiprocessors. In this context, this paper has two goals. One is to quantitatively characterize the SPLASH-2 programs in terms of fundamental properties and architectural interactions that are important to understand them well. The properties we study include the computational load balance, communication to computation ratio and traffic needs, important working set sizes, and issues related to spatial locality, as well as how these properties scale with problem size and the number of processors. The other, related goal is methodological: to assist people who will use the programs in architectural evaluations to prune the space of application and machine parameters in an informed and meaningful way. For example, by characterizing the working sets of the applications, we describe which operating points in terms of cache size and problem size are representative of realistic situations, which are not, and which re redundant. Using SPLASH-2 as an example, we hope to convey the importance of understanding the interplay of problem size, number of processors, and working sets in designing experiments and interpreting their results.

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The SPLASH-2 programs: characterization and methodological considerations

Mobile computing continuously evolve through the sustained effort of many researchers. It seamlessly augments users' cognitive abilities via compute-intensive capabilities such as speech recognition, natural language processing, etc. By thus empowering mobile users, we could transform many areas of human activity. This article discusses the technical obstacles to these transformations and proposes a new architecture for overcoming them. In this architecture, a mobile user exploits virtual machine (VM) technology to rapidly instantiate customized service software on a nearby cloudlet and then uses that service over a wireless LAN; the mobile device typically functions as a thin client with respect to the service. A cloudlet is a trusted, resource-rich computer or cluster of computers that's well-connected to the Internet and available for use by nearby mobile devices. Our strategy of leveraging transiently customized proximate infrastructure as a mobile device moves with its user through the physical world is called cloudlet-based, resource-rich, mobile computing. Crisp interactive response, which is essential for seamless augmentation of human cognition, is easily achieved in this architecture because of the cloudlet's physical proximity and one-hop network latency. Using a cloudlet also simplifies the challenge of meeting the peak bandwidth demand of multiple users interactively generating and receiving media such as high-definition video and high-resolution images. Rapid customization of infrastructure for diverse applications emerges as a critical requirement, and our results from a proof-of-concept prototype suggest that VM technology can indeed help meet this requirement.

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The Case for VM-Based Cloudlets in Mobile Computing

Cloud computing has recently emerged as a new paradigm for hosting and delivering services over the Internet. Cloud computing is attractive to business owners as it eliminates the requirement for users to plan ahead for provisioning, and allows enterprises to start from the small and increase resources only when there is a rise in service demand. However, despite the fact that cloud computing offers huge opportunities to the IT industry, the development of cloud computing technology is currently at its infancy, with many issues still to be addressed. In this paper, we present a survey of cloud computing, highlighting its key concepts, architectural principles, state-of-the-art implementation as well as research challenges. The aim of this paper is to provide a better understanding of the design challenges of cloud computing and identify important research directions in this increasingly important area.

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Cloud computing: state-of-the-art and research challenges

Migrating operating system instances across distinct physical hosts is a useful tool for administrators of data centers and clusters: It allows a clean separation between hard-ware and software, and facilitates fault management, load balancing, and low-level system maintenance.By carrying out the majority of migration while OSes continue to run, we achieve impressive performance with minimal service downtimes; we demonstrate the migration of entire OS instances on a commodity cluster, recording service downtimes as low as 60ms. We show that that our performance is sufficient to make live migration a practical tool even for servers running interactive loads.In this paper we consider the design options for migrating OSes running services with liveness constraints, focusing on data center and cluster environments. We introduce and analyze the concept of writable working set, and present the design, implementation and evaluation of high-performance OS migration built on top of the Xen VMM.

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Live migration of virtual machines

This paper presents MAUI, a system that enables fine-grained energy-aware offload of mobile code to the infrastructure. Previous approaches to these problems either relied heavily on programmer support to partition an application, or they were coarse-grained requiring full process (or full VM) migration. MAUI uses the benefits of a managed code environment to offer the best of both worlds: it supports fine-grained code offload to maximize energy savings with minimal burden on the programmer. MAUI decides at run-time which methods should be remotely executed, driven by an optimization engine that achieves the best energy savings possible under the mobile device's current connectivity constrains. In our evaluation, we show that MAUI enables: 1) a resource-intensive face recognition application that consumes an order of magnitude less energy, 2) a latency-sensitive arcade game application that doubles its refresh rate, and 3) a voice-based language translation application that bypasses the limitations of the smartphone environment by executing unsupported components remotely.

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MAUI: making smartphones last longer with code offload

As the availability of home broadband increases, there is an increasing need for a broadband-based home telemedicine architecture. A home tele-medicine architecture supporting broadband and remote training is presented.

REPETE2: A next generation home telemedicine architecture.

A proportional share scheduling apparatus and technique for scheduling resources among a plurality of clients, each of which has a proportional resource allocation of the total resources for the CPU. The clients are sorted in a run queue from the client having the largest proportional share allocation to the client having the smallest proportional share allocation (112). Starting from the beginning of the run queue, each client is run for a constant time quantum (130). If a client in the run queue has received more than its proportional resource allocation, the remaining clients in the run queue are skipped, and the clients are run from the beginning of the run queue (120). This process repeats until all clients have received service. Since the clients with the largest proportional share allocation are placed at the beginning of the run queue, they are allowed to receive more service than the clients having a smaller proportional resource allocation propositioned at the end of the run queue.

Apparatus and methods for proportional share scheduling

Methods for distributing and providing access to stored content from remote storage comprising; receiving a first request to access a first portion of stored content from a requestor, wherein the first request is in a file system request format; creating a placeholder for the stored content so that the placeholder has at least one parameter identical to the stored content and the placeholder can hold the first portion of the stored content and at least a second portion of the stored content; requesting the first portion of the stored content from remote storage; receiving the first portion of the stored content from the remote storage; storing the first portion of the stored content in the placeholder; and before the second portion of the stored content has been stored in the placeholder, providing the first portion of the stored content to the requestor using a file system response format.

Methods, systems, and media for stored content distribution and access

Developing CPU scheduling algorithms and understanding their impact in practice can be difficult and time consuming due to the need to modify and test operating system kernel code and measure the resulting performance on a consistent workload of real applications. To address this problem, we have developed WARP, a trace-driven virtualized scheduler execution environment that can dramatically simplify and speed the development of CPU schedulers. WARP is easy to use as it can run unmodified kernel scheduling code and can be used with standard user-space debugging and performance monitoring tools. It accomplishes this by virtualizing operating system and hardware events to decouple kernel scheduling code from its native operating system and hardware environment. A simple kernel tracing toolkit can be used with WARP to capture traces of all CPU scheduling related events from a real system. WARP can then replay these traces in its virtualized environment with the same timing characteristics as in the real system. Traces can be used with different schedulers to provide accurate comparisons of scheduling performance for a given application workload. We have implemented a WARP Linux prototype. Our results show that WARP can use application traces captured from its toolkit to accurately reflect the scheduling behavior of the real Linux operating system. Furthermore, testing scheduler behavior using WARP with application traces can be two orders of magnitude faster than running the applications using Linux.

WARP: Enabling fast CPU scheduler development and evaluation

Cloud photo services are widely used for persistent, convenient, and often free photo storage, which is especially useful for mobile devices. As users store more and more photos in the cloud, significant privacy concerns arise because even a single compromise of a user's credentials give attackers unfettered access to all of the user's photos. We have created Easy Secure Photos (ESP) to enable users to protect their photos on cloud photo services such as Google Photos. ESP introduces a new client-side encryption architecture that includes a novel format-preserving image encryption algorithm, an encrypted thumbnail display mechanism, and a usable key management system. ESP encrypts image data such that the result is still a standard format image like JPEG that is compatible with cloud photo services. ESP efficiently generates and displays encrypted thumbnails for fast and easy browsing of photo galleries from trusted user devices. ESP's key management makes it simple to authorize multiple user devices to view encrypted image content via a process similar to device pairing, but using the cloud photo service as a QR code communication channel. We have implemented ESP in a popular Android photos app for use with Google Photos and demonstrate that it is easy to use and provides encryption functionality transparently to users, maintains good interactive performance and image quality while providing strong privacy guarantees, and retains the sharing and storage benefits of Google Photos without any changes to the cloud service.

Jason Nieh

Papers

REPETE2: A next generation home telemedicine architecture.

Apparatus and methods for proportional share scheduling

Methods, systems, and media for stored content distribution and access

WARP: Enabling fast CPU scheduler development and evaluation

Encrypted cloud photo storage using Google photos