Byung-Gon Chun

Mobile applications are becoming increasingly ubiquitous and provide ever richer functionality on mobile devices. At the same time, such devices often enjoy strong connectivity with more powerful machines ranging from laptops and desktops to commercial clouds. This paper presents the design and implementation of CloneCloud, a system that automatically transforms mobile applications to benefit from the cloud. The system is a flexible application partitioner and execution runtime that enables unmo

Smartphones enable a new, rich user experience in pervasive computing, but their hardware is still very limited in terms of computation, memory, and energy reserves, thus limiting potential applications. In this paper, we propose a novel architecture that addresses these challenges via seamlessly—but partially—off-loading execution from the smartphone to a computational infrastructure hosting a cloud of smartphone clones. We outline new augmented execution opportunities for smartphones enabled b

This paper considers replication strategies for storage systems that aggregate the disks of many nodes spread over the Internet. Maintaining replication in such systems can be prohibitively expensive, since every transient network or host failure could potentially lead to copying a server's worth of data over the Internet to maintain replication levels. The following insights in designing an efficient replication algorithm emerge from the paper's analysis. First, durability can be provided separ

Researchers have made great strides in improving the fault tolerance of both centralized and replicated systems against arbitrary (Byzantine) faults. However, there are hard limits to how much can be done with entirely untrusted components; for example, replicated state machines cannot tolerate more than a third of their replica population being Byzantine. In this paper, we investigate how minimal trusted abstractions can push through these hard limits in practical ways. We propose Attested Appe

Mobile cloud computing applications run diverse workloads under diverse device platforms, networks, and clouds. Traditionally these applications are statically partitioned between weak devices and clouds, thus may be significantly inefficient in heterogeneous environments and workloads. We introduce the notion of dynamic partitioning of applications between weak devices and clouds and argue that this is key to addressing heterogeneity problems. We formulate the dynamic partitioning problem and d

We analyze replication of resources by server nodes that act selfishly, using a game-theoretic approach. We refer to this as the selfish caching problem. In our model, nodes incur either cost for replicating resources or cost for access to a remote replica. We show the existence of pure strategy Nash equilibria and investigate the price of anarchy, which is the relative cost of the lack of coordination. The price of anarchy can be high due to undersupply problems, but with certain network topolo

Reducing energy consumption in datacenters is key to building low cost datacenters. To address this challenge, we explore the potential of hybrid datacenter designs that mix low power platforms with high performance ones. We show how these designs can handle diverse workloads with different service level agreements in an energy efficient fashion. We evaluate the feasibility of our approach through experiments and then discuss the design challenges and options of hybrid datacenters.

We analyze the characteristics of overlay routing networks generated by selfish nodes playing competitive network construction games. We explore several networking scenarios - some simplistic, others more realistic - and analyze the resulting Nash equilibrium graphs with respect to topology, performance, and resilience. We find a fundamental tradeoff between performance and resilience, and show that limiting the degree of nodes is of great importance in controlling this balance. Further, by vary

Researchers have made great strides in improving the fault tolerance of both centralized and replicated systems against arbitrary (Byzantine) faults. However, there are hard limits to how much can be done with entirely untrusted components; for example, replicated state machines cannot tolerate more than a third of their replica population being Byzantine. In this paper, we investigate how minimal trusted abstractions can push through these hard limits in practical ways. We propose Attested Appe

Fast and efficient large content distribution is a challenge in the Internet due to its high traffic volume. In this paper, we propose ChunkCast, an anycast service that optimizes large content distribution. We present a distributed locality-aware directory that supports an efficient query for large content. Our system improves the median downloading time by at least 32% compared to previous approaches and emulates multicast trees without any explicit coordination of peers.

We examine the queuing dynamics at nodes in an ad hoc mobile network and evaluate network performance under different packet scheduling algorithms using Dynamic Source Routing (DSR) and Greedy Perimeter Stateless Routing (GPSR) as the underlying routing protocols. Typically, packet schedulers in ad hoc networks give priority to control packets over data packets and serve data packets in FIFO order. We find that setting priorities among data packets can decrease end-to-end packet delay significan

New single-machine environments are emerging from abundant computation available through multiple cores and secure virtualization. In this paper, we describe the research challenges and opportunities around diversified replication as a method to increase the Byzantine-fault tolerance (BFT) of single-machine servers to software attacks or errors. We then discuss the design space of BFT protocols enabled by these new environments. 1

Mobile applications are becoming increasingly ubiquitous and provide ever richer functionality on mobile devices. At the same time, such devices often enjoy strong connectivity with more powerful machines ranging from laptops and desktops to commercial clouds. This paper presents the design and implementation of CloneCloud, a system that automatically transforms mobile applications to benefit from the cloud. The system is a flexible application partitioner and execution runtime that enables unmo

Mobile application development is challenging for several reasons: intermittent and limited network connectivity, tight power constraints, server-side scalability concerns, and a number of fault-tolerance issues. Developers handcraft complex solutions that include client-side caching, conflict resolution, disconnection tolerance, and backend database sharding. To simplify mobile app development, we present Mobius, a system that addresses the messaging and data management challenges of mobile app