This project has been funded by the NSF grant CCR-9110938, and by IBM and Intel. This project considered the class of real-time systems characterized by the existence of strict timing constraints that must be satisfied if the system is to function correctly. We developed a number of new results in the theory of deterministic processor and resource allocation that incorporated more realistic assumptions about program execution constraints. These included analyses of: the problems of scheduling periodic and sporadic tasks non- preemptively [ Jeffay Stanat ] the problem of scheduling tasks that communicate and synchronize via shared memory [ Scheduling Sporadic Jeffay Resources ] [ Scheduling Sporadic Jeffay Preemptive ] and the problem of accounting for the overhead of interrupt handlers on the guaranteed response times of real-time tasks. [ Accounting Interrupt ] The algorithms developed were prototyped in an operating system kernel called YARTOS (Yet Another Real-Time Operating System). [ YARTOS Jeffay Stone ] The kernel supports a real-time, predictable-execution, programming model called the real- time producer/consumer (RTP/C) paradigm. [ Producer Consumer Jeffay ]
To evaluate the formal scheduling models, algorithms, and their realization in the YARTOS kernel, we built a desktop video conferencing system using the kernel. [ Kernel Support Jeffay Proceedings ] [ Kernel Support Jeffay Communications ] [ Workstation Kernel Jeffay Workshop ] [ Kernel Jeffay Live Workshop ] [ Kernel Support YARTOS ]
Additional, related research involved the development of real-time operating system support for multimedia applications such as videoconferencing. Results here included a set of adaptations for managing live audio and video streams in a distributed system [ Transport Display ] [ Adaptive Delivery Jeffay Stone Live ] [ Adaptive Delivery Jeffay Stone Data ] specifically, delay-jitter management techniques [ Emperical Study JItter ] [ Queue Monitoring Jitter ] and media scaling techniques for adaptive, rate-based, flow control. [ Two Dimensional Scaling Conference ] [ Two Dimensional Scaling Transactions ]
Much of the technology developed
under this grant has been adopted by the Intel Corporation for
the development of their LAN-based videoconferencing product.