TreadMarks is a distributed shared memory (DSM) system for standard Unix systems such as SunOS and Ultrix. This paper presents a performance evaluation of TreadMarks running on Ultrix using DECstation-5000/240's that are connected by a 100-Mbps switch-based ATM LAN and a 10-Mbps Ethernet. Our objective is to determine the efficiency of a user-level DSM implementation on commercially available workstations and operating systems. We achieved good speedups on the 8-processor ATM network for Jacobi (7.4), TSP (7.2), Quicksort (6.3), and ILINK (5.7). For a slightly modified version of Water from the SPLASH benchmark suite, we achieved only moderate speedups (4.0) due to the high communication and synchronization rate. Speedups decline on the 10-Mbps Ethernet (5.5 for Jacobi, 6.5 for TSP, 4.2 for Quicksort, 5.1 for ILINK, and 2.1 for Water), reflecting the bandwidth limitations of the Ethernet. These results support the contention that, with suitable networking technology, DSM is a...

We have improved the performance of the Mach 3.0 operating system by redesigning its internal thread and interprocess communication facilities to use continuations as the basis for control transfer. Compared to previous versions of Mach 3.0, our new system consumes 85% less space per thread. Cross-address space remote procedure calls execute 14% faster. Exception handling runs over 60% faster. In addition to improving system performance, we have used continuations to generalize many control transfer optimizations that are common to operating systems, and have recast those optimizations in terms of a single implementation methodology. This paper describes our experiences with using continuations in the Mach operating system. 1 Introduction We have achieved significant improvements in the performance of the Mach 3.0 operating system kernel [Accetta et al. 86] by redesigning it to use continuations as the basis for control transfers between execution contexts. In our system, a thread b...

We have added multiple threads of control to the Standard ML programming language. Standard ML's support for first-class functions and automatic storage management influenced the design in a number of ways. We demonstrate how other concurrency and synchronization operations, such as cobegin/coend, futures, and events, can be implemented in terms of the thread interface. Finally, we describe three implementations of the thread interface: a coroutine version, a uniprocessor preemptive version, and a multiprocessor Mach-based version. This research was sponsored in part by the Defense Advanced Research Projects Agency, Information Science and Technology Office, under the title "Research on Parallel Computing," ARPA Order No. 7330, issued by DARPA/CMO under Contract MDA972-90-C-0035, and in part by a National Science Foundation Graduate Fellowship. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official polici...

this article differentiate the exception-handling needs of CB-RTS as compared to other software paradigms and can serve as a driving force for future research into exception-handling technology.

Multiprocessors have been accepted as vehicles for improved computing speeds, cost/performance, and enhanced reliability or availability. However, the added performance requirements of user programs and functional capabilities of parallel hardware introduce new challenges to operating system design and implementation. This paper reviews research and commercial developments in multiprocessor operating system kernels from the late 1970's to the early 1990's. The paper first discusses some common operating system structuring techniques and examines the advantages and disadvantages of using each technique. It then identifies some of the major design goals and key issues in multiprocessor operating systems. Issues and solution approaches are illustrated by review of a variety of research or commercial multiprocessor operating system kernels. College of Computing Georgia Institute of Technology Atlanta, Georgia 30332--0280 Contents 1 Introduction 1 2 Structuring an Operating System 4 2....

This paper discusses the design and the operating system support necessary for providing asynchronous event handling in distributed, passive object-based programming environments, where objects are potentially shared by disparate applications. We discuss the necessity of thread-based as well as object-based event notification and how a variety of hard to solve distributed programming issues can be tackled by using the approach outlined in the design. Keywords: [Distributed Programming Environments, Passive Objects, Threads, Concurrency, Events] 1. Introduction Distributed programming has always been recognized as an order of magnitude more complex than centralized programming, and novel system structuring paradigms hold significant promise in making this problem tractable. Much of the current research on distributed operating systems and the associated programming environments are concerned with simplifying the task of distributed programming by providing constructs that make these ...

With programs growing in size and complexity, the quality and cost of developing and maintaining them are still deep concerns to software industries. Dynamically reconfigurable software, which is one paradigm for using component-based software, is a promising approach in reducing the developmental cost while increasing the quality and the reliability. For real-time embedded systems, a dynamically reconfigurable real-time software paradigm provides many major advantages over conventional real-time software development techniques. As with any other real-time software, dynamically reconfigurable software needs exception detection and handling mechanisms to satisfy reliability requirements. How-ever, the focus of developing reusable software has been on the structure of initialization and normal operation code within reusable components. This can make an application composed of reusable software non-deterministic and difficult to understand in the presence of errors. Even if 100 percent of modules are reused, there may still be the need for significant amounts of new code for error handling. Our goal is to create a structured exception handling mechanism for dynamically reconfigurable real-time software (DRRTS) that helps programmers to create reliable