Implementing new operating systems is tedious, costly, and often impractical except for large projects. The Flux OSKit addresses this problem in a novel way by providing clean, well-documented OS components designed to be reused in a wide variety of other environments, rather than defining a new OS structure. The OSKit uses unconventional techniques to maximize its usefulness, such as intentionally exposing implementation details and platform-specific facilities. Further, the OSKit demonstrates a technique that allows unmodified code from existing mature operating systems to be incorporated quickly and updated regularly, by wrapping it with a small amount of carefully designed “glue” code to isolate its dependencies and export well-defined interfaces. The OSKit uses this technique to incorporate over 230,000 lines of stable code including device drivers, file systems, and network protocols. Our experience demonstrates that this approach to component software structure and reuse has a surprisingly large impact in the OS implementation domain. Four real-world examples show how the OSKit is catalyzing research and development in operating systems and programming languages. 1

The Internet is rapidly changing from a set of wires and switches that carry packets into a sophisticated infrastructure that delivers a set of complex value-added services to end users. Services can range from bit transport all the way up to distributed value-added services like video teleconferencing, data mining, and distributed interactive simulations. Before such services can be supported in a general and dynamic manner, we have to develop appropriate resource management mechanisms. These resource management mechanisms must make it possible to identify and allocate resources that meet service or application requirements, support both isolation and controlled dynamic sharing of resources across organizations sharing physical resources, and be customizable so services and applications can tailor resource usage to optimize their performance. The Darwin project

In this chapter we present a study of the SPEC JVM98 benchmark suite at a dynamic platform-independent level. The results presented describe the inuence of class library code, the relative importance of various methods in the suite, as well as the sizes of the local variable, parameter and operand stacks. We also examine the dynamic bytecode instruction usage frequencies, and discuss their relevance. The inuence of the choice of Java source to bytecode compiler is shown to be relatively insigni cant at present.

The deployment of advanced network services such as virtual reality games, distributed simulation, and video conferencing, will require sophisticated resource management support. The reason is that the quality of the delivered service will depend both on what resources are allocated to the user, and how these resources are managed at runtime. This problem is challenging because the definition of Quality of Service (QoS) is in general user specific, so hardwired resource management mechanisms will not be sufficient. To address the runtime resource management problem, we introduce the concept of a delegate, a code segment that applications or service providers inject into the network to assist in the management of the network resources that are allocated to them. This approach allows users to tailor runtime resource management to best meet their specific needs. Moreover, since delegates execute inside the network, they can easily collect information on changing network conditions, and ca...

This paper describes the design, implementation, and experimental evaluation of a modular and extensible Java Virtua l Ma chine (JVM) infra structure, ca lled Jupiter. The infra structure is intended to servea sa vehicle for our resea+ h on scaD0K5 JVMa rchitectures fora 128-processor cluster of PC worksta ions, with support for sha15 memory in softwa65 Jupiter is constructed, usinga building blocka rchitecture, out of ma ny modules withsma ll, simple interfa ces. This flexible structure, simila r to UNIX r shellstha t build complex comma1 pipelines out of discrete progra+1 agr ws the r a id prototyping of ourresea0 h idea by confining cha nges in JVM design toa sma ll number of modules. In spite of this flexibility, Jupiter delivers good performa nce. Experimenta eva ua tion of the current implementa tion of Jupiter using the SPECjvm98 benchma rks showstha t it is ona vera1 2.65 times fa6 er tha n K a ea nd 2.20 slower tha n the Sun Microsystems JDK (interpreter versions only). By providing a flexible JVM infrastructure that delivers competitive performance, we believe we have developed a framework that supports further research into JVM scalability.

We envision the deployment of an electronic services market that will deliver a wide range of electronic services over networks. This market will allow applications to combine resources at endpoints with resources inside the network to deliver high-quality products to end-users. Electronic services will range from simple data delivery services to sophisticated value-added services such as video conferencing and data mining. We argue that the deployment of such a diverse set of services will be facilitated by the presence of an integrated set of customizable resource management mechanisms. In this paper, we introduce three concepts that respond to this need. First, the resources allocated to an application will be integrated in a virtual network that forms the basis of runtime resource management and quality of service optimization. Second, each resource is managed by a hierarchical resource manager that satisfies the combined priorities and constraints of the services and applications ...