Hideyuki Tokuda

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Process scheduling in real-time systems has almost invariably used one or more of three algorithms: fixed priority, FIFO, or round robin. The reasons for these choices are simplicity and speed in the operating system, but the cost to the system in terms of reliability and maintainability have not generally been assessed. This paper originates from the(More)
Distributed real-time systems play a very important role in our modern society. They are used in aircraft control, communication systems, military command and control systems, factory automation, and robotics. However, satisfying the rigid timing requirements of various real-time activities in distributed real-time systems often requires ad hoc methods to(More)
Multimedia applications have timing requirements that cannot generally be satisfied using the time-sharing scheduling algorithms of general purpose operating systems. Our approach is to provide the predictability of real-time systems while retaining the flexibility of a timesharing system. We designed a processor capacity reservation mechanism that isolates(More)
We've known for a while that the Internet has ossified as a result of the race to optimize existing applications or enhance security. NATs, performance-enhancing-proxies,firewalls and traffic normalizers are only a few of the middleboxes that are deployed in the network and look beyond the IP header to do their job. IP itself can't be extended because "IP(More)
Multimedia applications have timing requirements that cannot generally be satisfied using time-sharing scheduling algorithms and system structures. To effectively support these types of programs, operating systems must support processor capacity reservation. A capacity reservation and enforcement mechanism isolates programs from the timing and execution(More)
We propose a new object-oriented programming language called RTC++ for programming real-time applications. RTC++ is an extension of C++ and its features are to specify i) a real-time object which is an active entity, ii) timing constraints in an operation as well as in statements, and iii) a periodic task with rigid timing constraints. In this paper, we(More)
In this paper, we propose a scheme of rate control for continuous UDP ow with moderate fairness. First, per-packet Relative One-way Trip Time (ROTT) of a UDP stream at a receiver on the Internet is investigated extensively, and it is found that spikes with successive plots, which we call spike-trains, often appear on a time-ROTT graph. Also,(More)
Multipath transport protocols, which transmit data over multiple distinct paths in an end-to-end connection are introduced. However, they have a problem in terms of fairness. When the transmissions along several paths share the same bottleneck link, the multipath connection receives higher throughput than a competing regular TCP flow, because it executes(More)
ARTS is a distributed real-time operating system designed for a real-time systems testbed being developed at Camegle Mellon University. The objective of the testbed is to develop and verify advanced real-time computing technologies for a distributed environment. The tastbed consists of a set of SUN3 workstations connected by a real-time network based on(More)