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.

/pdf/the-splash-2-programs-characterization-and-methodological-14b6i8va45.pdf

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.

/pdf/the-case-for-vm-based-cloudlets-in-mobile-computing-1rofse2vmh.pdf

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.

/pdf/cloud-computing-state-of-the-art-and-research-challenges-49ws7tdgj3.pdf

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.

/pdf/live-migration-of-virtual-machines-o3cs0reg9z.pdf

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.

/pdf/maui-making-smartphones-last-longer-with-code-offload-go3o1uwp1u.pdf

MAUI: making smartphones last longer with code offload

As smartphones and tablets proliferate, there is a growing demand for multi-mobile computing, the ability to combine multiple mobile systems into more capable ones. We present M2, a system for multi-mobile computing that enables existing unmodified mobile apps to share and combine multiple devices, including cameras, displays, speakers, microphones, sensors, GPS, and input. M2 introduces a new data-centric approach that leverages higher-level device abstractions and hardware acceleration to efficiently share device data, not API calls. To support heterogeneous devices, M2 introduces device transformation, a new technique to mix and match different types of devices. Example transformations include combining multiple displays into a single larger display for better viewing, or substituting accelerometer for touchscreen input to provide a Nintendo Wii-like experience with existing mobile gaming apps. We have implemented M2 and show that it (1) operates across heterogeneous systems, including multiple versions of Android and iOS, (2) can enable unmodified Android apps to use multiple mobile devices in new and powerful ways, including supporting users with disabilities and better audio conferencing, and (3) can run apps across mobile systems with modest overhead and qualitative performance indistinguishable from using local device hardware.

https://dl.acm.org/doi/pdf/10.1145/3307334.3326096

Heterogeneous Multi-Mobile Computing

Continuing advances in hardware technology have enabled the proliferation of faster, cheaper, and more capable personal computers. Users of all backgrounds rely on their computers to handle ever-expanding information, communication, and computation needs. As users spend more time interacting with their computers, it is becoming increasingly important to archive and later search the knowledge, ideas and information that they have viewed through their computers. However, existing state-of-the-art web and desktop search tools fail to provide a suitable solution, as they focus on static, accessible documents in isolation. Thus, finding the information one has viewed among the ever-increasing and chaotic sea of data available from a computer remains a challenge. 
This dissertation introduces DejaView, a personal virtual computer recorder that enhances personal computers with the ability to process display-centric content to help users with all the information they see through their computers. DejaView continuously records a user's session to provide a complete WYSIWYS (What You Search Is What You've Seen) record of a desktop computing experience, enabling users to playback, browse, search, and revive records, making it easier to retrieve and interact with information they have seen before. 
DejaView records visual output, checkpoints corresponding application and file system states, and captures onscreen text with contextual information to index the record. A user can then browse and search the record for any visual information that has been previously displayed on the desktop, and revive and interact with the desktop computing state corresponding to any point in the record. DejaView introduces new, transparent operating system, display and file system virtualization techniques and novel semantic display-centric information recording, and combines them to provide its functionality without any modifications to applications, window systems, or operating system kernels. Our results demonstrate that DejaView can provide continuous low-overhead recording without any user-noticeable performance degradation, and allows users to playback, browse, search, and time-travel back to records fast enough for interactive use. 
This dissertation also demonstrates how DejaView's execution virtualization and recording extend beyond the desktop recorder context. We introduce a coordinated, parallel checkpoint-restart mechanism for distributed applications that minimizes synchronization overhead and uniquely supports complete checkpoint and restart of network state in a transport protocol independent manner, for both reliable and unreliable protocols. We introduce a scalable system that enables significant energy saving by migrating network state and applications off of idle hosts allowing the hosts to enter low-power suspend state, while preserving their network presence. Finally, we show how our techniques can be integrated into a commodity operating system, mainline Linux, thereby allowing the entire operating systems community to benefit from mature checkpoint-restart that is transparent, secure, reliable, efficient, and integral to the Linux kernel.

A personal virtual computer recorder

Methods, systems, and media for binary compatible graphics support in mobile operating systems are provided. In some embodiments, binary compatible graphics support can be provided by extending diplomatic functions to perform library-wide prelude and postlude operations in the context of the foreign operating system before and after domestic library usage. In some embodiments, binary compatible graphics support can be provided by using thread impersonation approaches that allow one thread to temporarily take on the persona of another thread to perform some action that may be tread-dependent. In some embodiments, binary compatible graphics support can be provided by using dynamic library replication approaches that load multiple, independent instances of a single library within the same process.

Methods, systems, and media for binary compatible graphics support in mobile operating systems

We present group round-robin (GRR) scheduling, a hybrid fair packet scheduling framework based on a grouping strategy that narrows down the traditional trade-off between fairness and computational complexity. GRR combines its grouping strategy with a specialized round-robin scheduling algorithm that utilizes the properties of GRR groups to schedule flows within groups in a manner that provides O(1) bounds on fairness with only O(1) time complexity. Under the practical assumption that GRR employs a small constant number of groups, we apply GRR to popular fair queuing scheduling algorithms and show how GRR can be used to achieve constant bounds on fairness and time complexity for these algorithms. We also present and prove new results on the fairness bounds for several of these fair queuing algorithms using a consistent fairness measure. We analyze the behavior of GRR and present experimental results that demonstrate how GRR can be combined with existing scheduling algorithms to provide much lower scheduling overhead and more than an order of magnitude better scheduling accuracy in practice than scheduling algorithms without GRR.

Group round robin

We present DeskPod, a portable system that provides a highly reliable desktop computing environment for mobile users by leveraging rapid improvements in capacity, cost, and size of portable storage devices. DeskPod enables a user?s live computing environment to be suspended to portable storage, carried around, easily copied for faultresilience, and resumed from the storage device to provide the user with the same persistent, personalized computing environment on another computer. DeskPod achieves this by providing a virtualization and checkpoint/restart mechanism that decouples a desktop computing environment from any single hardware device so that it can be stored and executed anywhere, improving desktop computing reliability by eliminating a potential single point of failure. We have implemented a Linux DeskPod prototype and demonstrate its ability to quickly suspend and resume desktop sessions, enabling a seamless mobile experience.

Jason Nieh

Papers

Heterogeneous Multi-Mobile Computing

A personal virtual computer recorder

Methods, systems, and media for binary compatible graphics support in mobile operating systems

Group round robin

Highly Reliable Mobile Desktop Computing in Your Pocket