Project Administration Data Sheet
نویسنده
چکیده
Ra is a native, minimal kernel for the Clouds distributed operating system. Clouds supports persistent virtual spaces, called objects and threads that direct computations through these spaces. Clouds is targeted to run in a compute-server — data-server environment, in which processing is done by threads executing on compute-servers (or workstations) and the objects will permanently residing on data•servers (also called file-servers). Service between data servers and workstations is handled by a distributed shared memory paradigm. The major function of Ra is to provide segment-based virtual memory management, and short term scheduling. Ra provides support for objects through a primitive abstraction called virtual spaces. Virtual spaces are composed of windows on segments. Ra provides support for threads throgh istbas. An isiba is the unit of activity supported by Ra. The Clouds system will be supported on top of Ra, by adding system-objects to Ra. System-objects provide services, such as communication, thread management, atomicity support, object naming and location, and device handling. Ra provides mechanisms that allow system-object to be plugged in and out of Ra dynamically. Ra also provides a set of kernel classes that allow machine dependent variables and interrupt services to be accessed from system objects in a uniform machine independent fashion. Thus Ra is a highly modular. expandable and flexible kernel. Ra is currently being implemented on a collection of Sun-3 workstations and will eventually run on a heterogeneous network of computers of varying sizes including multiprocessors. This paper describes the architecture and functionality of Ra, preliminary details on its implementation, and the envisioned strategy for building a distributed operating system (Clouds) on top of Ra (by adding appropriate system-objects). This work has been funded by NSF grant CCR-8619886,
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