This paper is concerned with the architecture and performance of systems that use a broadcast channel to deliver information to a community of users. lnformation is organized into units called pages, and at any instant of time, two or more users may request the same page. Broadcast delivery is attractive for such an environment because a single transmission of a page will satisfy all pending requests for that page. Three alternative architectures for broadcast information delivery systems are considered. They are one-way broadcast, two-way interaction, and hybrid one-way broadcasthwo-way interaction. An important design issue is the scheduling of page transmissions such that the user response time is minimized. For each architecture, existing scheduling algorithms are described, and their mean response time performance evaluated. Properties of scheduling algorithms that yield optimal mean response time are discussed. A comparative discussion of the performance differences of the three architectures is also provided.

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Teletext is a one-way information system where pages of information are broadcast to all users in a important consideration in the design of teletext syscontinuous manner. Systerc response time is a n tems. One of the factors contributing to response time is the order in which pages are broadcast. In this paper, we formulate the problem of deciding on the sequence of page transmissions as a Markovian decision process. Using this formulation we show that, from a response time point-of-view, a cyclic order of page transmissions is optimal.

In resource provisioning for cloud computing, an important issue is how resources may be allocated to an application mix such that the service level agreements (SLAs) of all applications are met. A performance model with two interactive job classes is used to determine the smallest number of servers required to meet the SLAs of both classes. For each class, the SLA is specified by the relationship: Prob [response time ≤ x] ≥ y. Two server allocation strategies are considered: shared allocation (SA) and dedicated allocation (DA). For the case of FCFS scheduling, analytic results for response time distribution are used to develop a heuristic algorithm that determines an allocation strategy (SA or DA) that requires the smallest number of servers. The effectiveness of this algorithm is evaluated over a range of operating conditions. The performance of SA with non-FCFS scheduling is also investigated. Among the scheduling disciplines considered, a new discipline called probability dependent priority is found to have the best performance in terms of requiring the smallest number of servers.