IBM

About: IBM is a company organization based out in Armonk, New York, United States. It is known for research contribution in the topics: Layer (electronics) & Cache. The organization has 134567 authors who have published 253905 publications receiving 7458795 citations. The organization is also known as: International Business Machines Corporation & Big Blue.

Optimistic recovery in distributed systems

Abstract: Optimistic Recovery is a new technique supporting application-independent transparent recovery from processor failures in distributed systems. In optimistic recovery communication, computation and checkpointing proceed asynchronously. Synchronization is replaced by causal dependency tracking, which enables a posteriori reconstruction of a consistent distributed system state following a failure using process rollback and message replay.Because there is no synchronization among computation, communication, and checkpointing, optimistic recovery can tolerate the failure of an arbitrary number of processors and yields better throughput and response time than other general recovery techniques whenever failures are infrequent.

CUTE: constrained and unconstrained testing environment

Abstract: The purpose of this article is to discuss the scope and functionality of a versatile environment for testing small- and large-scale nonlinear optimization algorithms. Although many of these facilities were originally produced by the authors in conjunction with the software package LANCELOT, we believe that they will be useful in their own right and should be available to researchers for their development of optimization software. The tools can be obtained by anonymous ftp from a number of sources and may, in many cases, be installed automatically. The scope of a major collection of test problems written in the standard input format (SIF) used by the LANCELOT software package is described. Recognizing that most software was not written with the SIF in mind, we provide tools to assist in building an interface between this input format and other optimization packages. These tools provide a link between the SIF and a number of existing packages, including MINOS and OSL. Additionally, as each problem includes a specific classification that is designed to be useful in identifying particular classes of problems, facilities are provided to build and manage a database of this information. There is a Unix and C shell bias to many of the descriptions in the article, since, for the sake of simplicity, we do not illustrate everything in its fullest generality. We trust that the majority of potential users are sufficiently familiar with Unix that these examples will not lead to undue confusion.

Enhancing lifetime and security of PCM-based main memory with start-gap wear leveling

Abstract: Phase Change Memory (PCM) is an emerging memory technology that can increase main memory capacity in a cost-effective and power-efficient manner. However, PCM cells can endure only a maximum of 107 - 108 writes, making a PCM based system have a lifetime of only a few years under ideal conditions. Furthermore, we show that non-uniformity in writes to different cells reduces the achievable lifetime of PCM system by 20x. Writes to PCM cells can be made uniform with Wear-Leveling. Unfortunately, existing wear-leveling techniques require large storage tables and indirection, resulting in significant area and latency overheads. We propose Start-Gap, a simple, novel, and effective wear-leveling technique that uses only two registers. By combining Start-Gap with simple address-space randomization techniques we show that the achievable lifetime of the baseline 16GB PCM-based system is boosted from 5% (with no wear-leveling) to 97% of the theoretical maximum, while incurring a total storage overhead of less than 13 bytes and obviating the latency overhead of accessing large tables. We also analyze the security vulnerabilities for memory systems that have limited write endurance, showing that under adversarial settings, a PCM-based system can fail in less than one minute. We provide a simple extension to Start-Gap that makes PCM-based systems robust to such malicious attacks.

Networked virtual environments: design and implementation

Abstract: 1. The Promises and Challenges of Networked Virtual Environments. What Is a Networked Virtual Environment? Graphics Engines and Displays. Control and Communication Devices. Processing Systems. Data Network. Challenges in Net-VE Design and Development. Network Bandwidth. Heterogeneity. Distributed Interaction. Real-Time System Design and Resource Management. Failure Management. Scalability. Deployment and Configuration. Conclusion. References. 2. The Origin of Networked Virtual Environments. Department of Defense Networked Virtual Environments. SIMNET. Distributed Interactive Simulation. Networked Games and Demos. SGI Flight and Dogfight. Doom. Other Games. Academic Networked Virtual Environments. NPSNET. PARADISE. DIVE. Brick Net. MR Toolkit Peer Package. Others. Conclusion. References. 3. A Networking Primer. Fundamentals of Data Transfer. Network Latency. Network Bandwidth. Network Reliability. Network Protocol. The BSD Sockets Architecture. Sockets and Ports. The Internet Protocol. Introducing the Internet Protocols for Net-Ves. Transmission Control Protocol. User Datagram Protocol. IP Broadcasting Using UDP. IP Multicasting. Selecting a Net-VE Protocol. Using TCP/IP. Using UDP/IP. Using IP Broadcasting. Using IP Multicasting. Conclusion. References. 4. Communication Architectures. Two Players on a LAN. Multiplayer Client-Server Systems. Multiplayer Client-Server, with Multiple-Server Architectures. Peer-to-Peer Architectures. Conclusion. References. 5. Managing Dynamic Shared State. The Consistency-Throughput Tradeoff. Maintaining Shared State Inside Centralized Repositories. Reducing Coupling through Frequent State Regeneration. Dead Reckoning of Shared State. Conclusion. References. 6. Systems Design. One Thread, Multiple Threads. Important Subsystems. Conclusion. References and Further Reading. 7. Resource Management for Scalability and Performance. An Information-Centric View of Resources. Optimizing the Communications Protocol. Controlling the Visibility of Data. Taking Advantage of Perceptual Limitations. Enhancing the System Architecture. Conclusion. References. 8. Internet Networked Virtual Environments. VRML-Based Virtual Environments. Virtual Reality Transfer Protocol. Internet Gaming. Conclusion. References. 9. Perspective and Predictions. Better Library Support. Toward a Better Internet. Research Frontiers. Past, Present, and Future. References. Appendix: Network Communication in C, C++, and Java. Using TCP/IP from C and C++. Managing Concurrent Connections in C and C++. Using TCP/IP from Java. Managing Concurrent Connections in Java. Using UDP/IP from C and C++. Using UDP/IP from Java. Broadcasting from C and C++. Broadcasting from Java. Multicasting from C and C++. Multicasting from Java. References. Index. 0201325578T04062001