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Given a set of machines and a set of Web applications with dynamically changing demands, an online application placement controller decides how many instances to run for each application and where to put them, while observing all kinds of resource constraints. This NP hard problem has real usage in commercial middleware products. Existing approximation(More)
Since many Internet applications employ a multi-tier architecture, in this paper, we focus on the problem of analytically modeling the behavior of such applications. We present a model based on a network of queues, where the queues represent different tiers of the application. Our model is sufficiently general to capture (i) the behavior of tiers with(More)
We present an architecture and prototype implementation of a performance management system for cluster-based web services. The system supports multiple classes of web services traffic and allocates server resources dynamically so to maximize the expected value of a given cluster utility function in the face of fluctuating loads. The cluster utility is a(More)
Since many Internet applications employ a multitier architecture, in this article, we focus on the problem of analytically modeling the behavior of such applications. We present a model based on a network of queues where the queues represent different tiers of the application. Our model is sufficiently general to capture (i) the behavior of tiers with(More)
We introduce and evaluate a middleware clustering technology capable of allocating resources to web applications through dynamic application instance placement. We define application instance placement as the problem of placing application instances on a given set of server machines to adjust the amount of resources available to applications in response to(More)
What is the impact of autocorrelation of Variable Bit Rate (VBR) video sources on real-time scheduling algorithms? Our results show that the impact of long term, or interframe, au-tocorrelation is negligible, while the impact of short term, or intraframe, autocorrelation can be signiicant. Such results are essentially independent of the video coding scheme(More)
A framework for joint scheduling and admission control in broadband switching systems is developed according to a principle of separation between these two levels of control. It is shown how an admission control strategy can be tailored to a particular mix of traac by making use of high-level information from the scheduler. This principle is presented in(More)
In this paper we present our experience in building the Research Compute Cloud (RC2), a cloud computing platform for use by the worldwide IBM Research community. Within eleven months of its official release RC2 has reached a community of 631 users spanning 34 countries , and serves on average 350 active users and 1800 active VM instances per month. Besides(More)
Can the introduction of traac classes improve upon the performance of ATM networks? We investigate this issue within the framework provided by a class of networks that guarantees quality of service. To provide a meaningful comparison we deene the concept of schedulable region, a region in the space of loads for which the quality of service is guaranteed. We(More)