Ibm Systems Journal
Latest articles in this journal
IBM Systems Journal, Volume 47, pp 221-236; https://doi.org/10.1147/sj.472.0221
Read-copy update (RCU) is a synchronization mechanism in the Linux™ kernel that provides significant improvements in multiprocessor scalability by eliminating the writer-delay problem of readers-writer locking. RCU implementations to date, however, have had the side effect of expanding non-preemptible regions of code, thereby degrading real-time response. We present here a variant of RCU that allows preemption of read-side critical sections and thus is better suited for real-time applications. We summarize priority-inversion issues with locking, present an overview of the RCU mechanism, discuss our counter-based adaptation of RCU for real-time use, describe an additional adaptation of RCU that permits general blocking in read-side critical sections, and present performance results. We also discuss an approach for replacing the readers-writer synchronization with RCU in existing implementations.
IBM Systems Journal, Volume 47, pp 377-396; https://doi.org/10.1147/sj.473.0377
IBM Systems Journal, Volume 47, pp 29-39; https://doi.org/10.1147/sj.471.0029
IBM Systems Journal, Volume 47, pp 71-85; https://doi.org/10.1147/sj.471.0071
Service systems produce all services of significance and scope, yet the concept of a service system is not well articulated in the service literature. This paper presents three interrelated frameworks as a first attempt to define the fundamentals of service systems. These frameworks identify basic building blocks and organize important attributes and change processes that apply across all service systems. Although relevant regardless of whether a service system uses information technology, the frameworks are also potentially useful in visualizing the realities of moving toward automated service architectures. This paper uses two examples, one largely manual and one highly automated, to illustrate the potential usefulness of the three frameworks, which can be applied together to describe, analyze, and study how service systems are created, how they operate, and how they evolve through a combination of planned and unplanned change.
IBM Systems Journal, Volume 47, pp 605-619; https://doi.org/10.1147/sj.2008.5386516
IBM Systems Journal, Volume 47, pp 1-1; https://doi.org/10.1147/sj.473.0354
IBM Systems Journal, Volume 47, pp 3-4; https://doi.org/10.1147/sj.471.0003
IBM Systems Journal, Volume 47, pp 197-206; https://doi.org/10.1147/sj.472.0197
This paper introduces responsive systems: systems that are real-time, event-based, or time-dependent. There are a number of trends that are accelerating the adoption of responsive systems: timeliness requirements for business information systems are becoming more prevalent, embedded systems are increasingly integrated into soft real-time command-and-control systems, improved message-oriented middleware is facilitating growth in event-processing applications, and advances in service-oriented and component-based techniques are lowering the costs of developing and deploying responsive applications. The use of responsive systems is illustrated here in two application areas: the defense industry and online gaming. The papers in this special issue of the IBM Systems Journal are then introduced. The paper concludes with a discussion of the key remaining challenges in this area and ideas for further work.
IBM Systems Journal, Volume 47, pp 207-220; https://doi.org/10.1147/sj.472.0207