Scheduling soft real-time jobs over dual non-real-time servers

In this paper, we consider soft real-time systems with redundant off-the-shelf processing components (e.g., CPU, disk, network), and show how applications can exploit the redundancy to improve the system's ability of meeting response time goals (soft deadlines). We consider two scheduling policies, one that evenly distributes load (Balance), and one that partitions load according to job slackness (Chop). We evaluate the effectiveness of these policies through analysis and simulation. Our results show that by intelligently distributing jobs by their slackness amount the servers, Chop can significantly improve real-time performance. ©1996 IEEE.published_or_final_versio

Literature Review For Networking And Communication Technology

Report documents the results of a literature search performed in the area of networking and communication technology

State-of-the-art Assessment For Simulated Forces

Summary of the review of the state of the art in simulated forces conducted to support the research objectives of Research and Development for Intelligent Simulated Forces

A system for improving the quality of real-time services on the internet

Real-time Internet services are becoming more popular every day, and Voice over Internet Protocol (VOIP) is arguably the most popular of these, despite the quality and reliability problems that are so characteristic of VOIP. This thesis proposes to apply a routing technique called Fully Redundant Dispersity Routing to VOIP and shows how this mitigates these problems to deliver a premium service that is more equal to traditional telephony than VOIP is currently.Fully Redundant Dispersity Routing uses the path diversity readily available in the Internet to route complete copies of the data to be communicated over multiple paths. This allows the effect of a failure on a path to be reduced, and possibly even masked completely, by the other paths. Significantly, rather than expecting changes of the Internet that will improve real-time service quality, this approach simply changes the manner in which real-time services use the Internet, leaving the Internet itself to stay the way it is.First, real VOIP traffic in a commercial call centre is measured (1) to establish a baseline of current quality characteristics against which the effects of Fully Redundant Dispersity Routing may be measured, and (2) as a source of realistic path characteristics. Simulations of various Fully Redundant Dispersity Routing systems that adopt the measured VOIP traffic characteristics then (1) show how this routing technique mitigates quality and reliability problems, and (2) quantify the quality deliverable with the VOIP traffic characteristics measured. For example, quantifying quality as a Mean Opinion Score (MOS) estimated from the measurements with the International Telecommunication Union’s E-model, slightly more than 1 in every 23 of the VOIP telephone calls measured in the call centre is likely to be perceived to be of a quality with which humans would be less than very satisfied. Simulations carried out for this thesis show that using just two paths adopting the same measurements, Fully Redundant Dispersity Routing may increase quality to reduce that proportion to slightly less than 1 in every 10 000 VOIP telephone calls