Huynh, Khoa Dang.

We propose a methodology to effectively characterize the architecture and system performance of distributed systems designed to operate in frame-based real-time environments. Important characteristics that define the real-time performance of a distributed system are identified and classified at the hardware, operating system, and user application levels. A synthetic workload model, called the Distributed Real-Time Workload (DRTW), is designed to fully characterize a broad range of real-time applications and to exercise a single- or multiple-node distributed system under measurement. A set of data collection tools to obtain empirical performance data at different levels of a distributed system is also proposed. For the purpose of illustration, these tools are used to obtain data on several real-time systems from Encore Computer Corporation.

In this dissertation, an object-based I/O architecture for personal computers (PCs) and workstations is proposed. The proposed architecture allows the flexibility of having I/O processing performed as much as possible by intelligent I/O adapters, or by the host processor, or by any processor in the system, depending on application requirements and underlying hardware capabilities. It keeps many good features of current I/O architectures, while providing more flexibility to take advantage of new hardware technologies, promote architectural openness, provide better performance and higher reliability. The proposed architecture introduces a new definition of I/O subsystems and makes use of concurrent object-oriented technology. It combines the notions of object and thread into something called an active object. All concurrency abstractions required by the proposed architecture are provided through external libraries on top of existing sequential object-oriented languages, without any changes to the syntax and semantics of these languages. We also evaluate the performance of optimal implementations of the proposed I/O architecture against other I/O architectures in three popular, PC-based, distributed environments: network file server, video server, and video conferencing. Using the RESearch Queueing Modeling Environment (RESQME), we have developed detailed simulation models for various implementations of the proposed I/O architecture and two other existing I/O architectures: a conventional, interrupt-based I/O architecture and a peer-to-peer I/O architecture. Our simulation results indicate that, on several different hardware platforms, the proposed I/O architecture outperforms both existing architectures in all three distributed environments considered.