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We consider the problem of providing vehicular Internet access using roadside 802.11 access points. We build on previous work in this area [18, 8, 5, 11] with an extensive experimental analysis of protocol operation at a level of detail not previously explored. We report on data gathered with four capture devices from nearly 50 experimental runs conducted(More)
This paper introduces Time-lined TCP (TLTCP). TLTCP is a protocol designed to provide TCP-friendly delivery of time-sensitive data to applications that are loss-tolerant, such as streaming media players. Previous work on unicast delivery of streaming media over the Internet proposes using UDP and performs congestion control at the user level by regulating(More)
A multiprocessor system is unlikely to have access to information about the execution characteristics of the jobs it is to schedule. In this work, we are interested in scheduling algorithms for batch jobs that require no such knowledge (such algorithms are called non-clairvoyant). Preemptive scheduling (i.e., redistribution of processors) is important to(More)
We study the problem of processor scheduling for n parallel jobs applying the method of competitive analysis. We prove that for jobs with a single phase of parallelism, a preemptive scheduling algorithm without information about job execution time can achieve a mean completion time within 2 − 2 n+1 times the optimum. In other words, we prove a competitive(More)
When a roadside 802.11-based wireless access point is shared by more than one vehicle, the vehicle with the lowest transmission rate reduces the effective transmission rate of all other vehicles. This <i>performance anomaly</i> [9] degrades both individual and overall throughput in such multi-vehicular environments. Observing that every vehicle eventually(More)
Acknowlegement I am grateful to my supervisor, Dr. Ken Sevcik. Without his support and guidance, this thesis could not have been nished. I would like to thank Dr. Songnian Zhou for being my second reader. His valuable suggestions have helped to improve this thesis to a great extend. I would also like to thank Tim Brecht for helping me implement the(More)
In this paper, we describe the design of a system, called ParaWeb, for utilizing Internet or intra-net computing resources in a seamless fashion. The goal is to allow users to execute serial programs on faster compute servers or parallel programs on a variety of possibly heterogeneous hosts. ParaWeb provides extensions to the Java programming environment(More)
Large-scale Non-Uniform Memory Access (NUMA) multiprocessors are gaining increased attention due to their potential for achieving high performance through the replication of relatively simple components. Because of the complexity of such systems, scheduling algorithms for parallel applications are crucial in realizing the performance potential of these(More)
The rapid proliferation of the WorldWide Web has been due to the seamless access it provides to information that is distributed both within organizations and around the world. In this paper, we describe the design and implementation of a system, called Ajents, which provides the software infrastructure necessary to support a similar level of seamless access(More)
In systems that support garbage collection, a tension exists between collecting garbage too frequently and not collecting it frequently enough. Garbage collection that occurs too frequently may introduce unnecessary overheads at the risk of not collecting much garbage during each cycle. On the other hand, collecting garbage too infrequently can result in(More)