Richard West

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This paper describes an algorithm, called Dynamic Window-Constrained Scheduling (DWCS), designed to meet the service constraints on packets from multiple, network-bound media streams with different performance objectives. Using only two attributes, a deadline and a loss-tolerance per packet stream, DWCS: (1) can limit the number of late packets over finite(More)
With the increased use of "Virtual Machines" (VMs) as vehicles that isolate applications running on the same host, it is necessary to devise techniques that enable multiple VMs to share underlying resources both fairly and efficiently. To that end, one common approach is to deploy complex resource management techniques in the hosting infrastructure.(More)
This paper describes an algorithm for scheduling packets in real-time multimedia data streams. Common to these classes of data streams are service constraints in terms of bandwidth and delay. However, it is typical for real-time multimedia streams to tolerate bounded delay variations and, in some cases, finite losses of packets. We have therefore developed(More)
In most operating systems, the handling of interrupts is typically performed within the address space of the kernel. Moreover, interrupt handlers are invoked asynchronously during the execution of arbitrary processes. Unfortunately, this allows for a process’s time quantum to be consumed by arbitrary interrupt handling. To avoid significant impact to(More)
This paper describes the scheduling framework for a new operating system called "Quest". The three main goals of Quest are to ensure safety, predictability and efficiency of software execution. For this paper, we focus on one aspect of predictability, involving the integrated management of tasks and I/O events such as interrupts. Quest's scheduling(More)
Shared caches in multicore processors are subject to contention from co-running threads. The resultant interference can lead to highly-variable performance for individual applications. This is particularly problematic for real-time applications, requiring predictable timing guarantees. Previous work has applied page coloring techniques to partition a shared(More)
This paper presents the embedded construction and experimental results for a media scheduler on i960 RD equipped I2O Network Interfaces (NI) used for streaming. We utilize the Distributed Virtual Communication Machine (DVCM) infrastructure developed by us which allows run-time extensions to provide scheduling for streams that may require it. The scheduling(More)
This paper describes how Dynamic WindowConstrained Scheduling (DWCS) can guarantee real-time service to packets from multiple streams with different performance objectives. We show that: (1) DWCS can guarantee that no more than x packets miss their deadlines for every y consecutive packets requiring service, as long as the minimum aggregate bandwidth(More)
The spectral properties of a rigidified trimethine cyanine dye, Cy3B™ have been characterised. This probe has excellent fluorescent properties, good water solubility and can be bioconjugated. The emission properties of this fluorophore have also been investigated upon conjugation to an antibody. This study compared the conjugated emission properties of Cy3B(More)
Real-time media servers need to service hundreds and, possibly, thousands of clients, each with their own quality of service (QoS) requirements. To guarantee such diverse QoS requires fast and efficient scheduling support at the server. This paper describes the practical issues concerned with the implementation of a scalable real-time packet scheduler(More)