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24
Multiprocessor Scheduling with Rejection
, 1996
"... We consider a version of multiprocessor scheduling with the special feature that jobs may be rejected at a certain penalty. An instance of the problem is given by m identical parallel machines and a set of n jobs, each job characterized by a processing time and a penalty. In the online version t ..."
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Cited by 38 (3 self)
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We consider a version of multiprocessor scheduling with the special feature that jobs may be rejected at a certain penalty. An instance of the problem is given by m identical parallel machines and a set of n jobs, each job characterized by a processing time and a penalty. In the online version the jobs arrive one by one and we have to schedule or reject a job before we have any information about future jobs. The objective is to minimize the makespan of the schedule for accepted jobs plus the sum of the penalties of rejected jobs. The main result is a 1 + OE 2:618 competitive algorithm for the online version of the problem, where OE is the golden ratio. A matching lower bound shows that this is the best possible algorithm working for all m. For fixed m we give improved bounds, in particular for m = 2 we give an optimal OE 1:618 competitive algorithm. For the offline problem we present a fully polynomial approximation scheme for fixed m and a polynomial approximation sche...
A Survey of Adaptive Optimization in Virtual Machines
 PROCEEDINGS OF THE IEEE, 93(2), 2005. SPECIAL ISSUE ON PROGRAM GENERATION, OPTIMIZATION, AND ADAPTATION
, 2004
"... Virtual machines face significant performance challenges beyond those confronted by traditional static optimizers. First, portable program representations and dynamic language features, such as dynamic class loading, force the deferral of most optimizations until runtime, inducing runtime optimiza ..."
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Cited by 35 (5 self)
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Virtual machines face significant performance challenges beyond those confronted by traditional static optimizers. First, portable program representations and dynamic language features, such as dynamic class loading, force the deferral of most optimizations until runtime, inducing runtime optimization overhead. Second, modular
On Page Migration and Other Relaxed Task Systems
, 1997
"... This paper is concerned with the page migration (or file migration) problem [BS89] as part of a large class of online problems. The page migration problem deals with the management of pages residing in a network of processors. In the classical problem there is only one copy of each page which is ..."
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Cited by 28 (4 self)
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This paper is concerned with the page migration (or file migration) problem [BS89] as part of a large class of online problems. The page migration problem deals with the management of pages residing in a network of processors. In the classical problem there is only one copy of each page which is accessed by different processors over time. The page is allowed to be migrated between processors. However a migration incurs higher communication cost than an access (proportionally to the page size). The problem is that of deciding when and where to migrate the page in order to lower access costs. A more general setting is the kpage migration where we wish to maintain k copies of the page. The page migration problems are concerned with a dilemma common to many online problems: determining when is it beneficial to make configuration changes. We deal with the relaxed task systems model which captures a large class of problems of this type, that can be described as the generalizati...
On Capital Investment
, 1996
"... We deal with the problem of making capital investments in machines for manufacturing a product. Opportunities for investment occur over time, every such option consists of a capital cost for a new machine and a resulting productivity gain, i.e., a lower production cost for one unit of product. T ..."
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Cited by 14 (1 self)
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We deal with the problem of making capital investments in machines for manufacturing a product. Opportunities for investment occur over time, every such option consists of a capital cost for a new machine and a resulting productivity gain, i.e., a lower production cost for one unit of product. The goal is that of minimizing the total production costs and capital costs when future demand for the product being produced and investment opportunities are unknown. This can be viewed as a generalization of the skirental problem and related to the mortgage problem [3].
On comparing the power of robots
 International Journal of Robotics Research. Under review
"... Robots must complete their tasks in spite of unreliable actuators and limited, noisy sensing. In this paper, we consider the information requirements of such tasks. What sensing and actuation abilities are needed to complete a given task? Are some robot systems provably “more powerful, ” in terms of ..."
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Cited by 11 (3 self)
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Robots must complete their tasks in spite of unreliable actuators and limited, noisy sensing. In this paper, we consider the information requirements of such tasks. What sensing and actuation abilities are needed to complete a given task? Are some robot systems provably “more powerful, ” in terms of the tasks they can complete, than others? Can we find meaningful equivalence classes of robot systems? This line of research is inspired by the theory of computation, which has produced similar results for abstract computing machines. The basic idea is a dominance relation over robot systems that formalizes the idea that some robots are stronger than others. This comparison, which is based on the how the robots progress through their information spaces, induces a partial order over the set of robot systems. We prove some basic properties of this partial order and show that it is directly related to the robots’ ability to complete tasks. We give examples to demonstrate the theory, including a detailed analysis of a limitedsensing global localization problem. 1
On the Computational Complexity and Effectiveness of Nhub ShortestPath Routing
"... In this paper we study the computational complexity and effectiveness of a concept we term “Nhub ShortestPath Routing ” in IP networks. Nhub ShortestPath Routing allows the ingress node of a routing domain to determine up to N intermediate nodes (“hubs”) through which a packet will pass before r ..."
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Cited by 8 (1 self)
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In this paper we study the computational complexity and effectiveness of a concept we term “Nhub ShortestPath Routing ” in IP networks. Nhub ShortestPath Routing allows the ingress node of a routing domain to determine up to N intermediate nodes (“hubs”) through which a packet will pass before reaching its final destination. This facilitates better utilization of the network resources, while allowing the network routers to continue to employ the simple and wellknown shortestpath routing paradigm. Although this concept has been proposed in the past, this paper is the first to investigate it in depth. We apply Nhub ShortestPath Routing to the problem of minimizing the maximum load in the network. We show that the resulting routing problem is NPcomplete and hard to approximate. However, we propose efficient algorithms for solving it both in the online and the offline contexts. Our results show that Nhub ShortestPath Routing can increase network utilization significantly even for. Hence, this routing paradigm should be considered as a powerful mechanism for future datagram routing in the Internet.
On Multithreaded Paging
, 1996
"... In this paper we introduce a generalization of Paging to the case where there are many threads of requests. This models situations in which the requests come from more than one independent source. Hence, apart from deciding how to serve a request, at each stage it is necessary to decide which reques ..."
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Cited by 6 (3 self)
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In this paper we introduce a generalization of Paging to the case where there are many threads of requests. This models situations in which the requests come from more than one independent source. Hence, apart from deciding how to serve a request, at each stage it is necessary to decide which request to serve among several possibilities. Four different problems arise whether we consider fairness restrictions or not, with finite or infinite input sequences. We study all of them, proving lower and upper bounds for the competitiveness of online algorithms. The main results presented in this paper may be summarized as follows. When no fairness restrictions are imposed it is possible to obtain good competitive ratios; on the other hand, for the fair case in general there exist no competitive algorithms.
Routing and Scheduling File Transfers in PacketSwitched Networks
 Journal of Computing and Information
, 1994
"... Data traffic in networks has always been dominated by file transfers, an observation that has motivated previous work in scheduling file transfers. While these previous research contributions address file transfers, they do not address the special considerations required of packetswitched networks, ..."
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Cited by 6 (3 self)
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Data traffic in networks has always been dominated by file transfers, an observation that has motivated previous work in scheduling file transfers. While these previous research contributions address file transfers, they do not address the special considerations required of packetswitched networks, in particular the issues of routing and of simultaneous transmissions of files. In this paper, we generalize previous formulations of the problem to include routing and to allow for simultaneous transmissions of several files. A few theoretical results are presented. Keywords: Data transfers, File transfers, Scheduling, Routing, Large scale networking applications, NPCompleteness, Algorithms. 1 Introduction We consider the joint problem of scheduling and routing the transfers of very large files. Our research is motivated by the increasing size and ambition of future networking applications, many of which will result in the movement of very large amounts of data across networks. For examp...
AverageCase Competitive Analyses for SkiRental Problems
, 2002
"... Abstract. Let s be the ratio of the cost for purchasing skis over the cost for renting them. Then the famous result for the skirental problem shows that skiers should buy their skis after renting them (s − 1). In practice, however, it appears that many skiers buy their skis before this optimal poin ..."
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Cited by 5 (0 self)
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Abstract. Let s be the ratio of the cost for purchasing skis over the cost for renting them. Then the famous result for the skirental problem shows that skiers should buy their skis after renting them (s − 1). In practice, however, it appears that many skiers buy their skis before this optimal point of time and also many skiers keep renting them forever. In this paper we show that these behaviors of skiers are quite reasonable by using an averagecase competitive ratio. For an exponential input distribution times, which gives us an optimal competitive ratio of 2 − 1 s ≤ s, then skiers should rent their skis forever and (ii) otherwise should purchase them after renting approximately s 2 λ (< s) times. Thus averagecase competitive analyses give us the result which differs from the worstcase competitive analysis and also differs from the traditional average cost analysis. Other distributions and related problems are also discussed. f(t) = λe −λt, optimal strategies are (i) if 1 λ 1