Browsing by Subject "Constraint programming"
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Item Open Access Temperature-aware core mapping for heterogeneous 3D NoC design through constraint programming(Institute of Electrical and Electronics Engineers, 2020) Demiriz, A.; Ahangari, Hamzeh; Öztürk, ÖzcanIn the context of Network-on-Chip (NoC) based Chip Multiprocessor (CMP) design, core mapping for application specific systems is a challenging problem. In such designs, various decisions have to be made that affect performance and power consumption. Moreover, in emerging 3D NoC systems, by intensification of cooling issues, temperature constraints on hot-spots are added, and problem becomes more complicated. In this paper, an earlier Constraint Programming (CP) methodology for heterogeneous 2D NoC design is extended to 3D model, while critical temperature constraints are accounted. In a single-stage, our approach can choose core types from a set of low, medium and high power, and assign them to appropriate places on the mesh which minimizes the overall computation time and communication cost while satisfying the temperature constraints. To achieve our objective, in addition to cores placement problem, tasks should also be scheduled on corresponding cores with matching performance levels to minimize the overall completion time (makespan). Experimental results show that task completion times are more dependent on the mesh structure for our benchmark data. 3D mesh structures may yield shorter task completion times, without compromising thermal constraints. On the other hand, restricting the peak temperature naturally requires the usage of low-performance computing elements which inherently may delay the processing time.Item Open Access A timetabling problem: constraint and mathematical programming approaches(Bilkent University, 2000-06) Botsalı, Ahmet RehaConstraint programming is a relatively new approach far solving combinatorial optimization problems. This approach is especially effective far large scale scheduling problems with side conditions. University course scheduling problem is one of the hard problems in combinatorial optimization. Furthermore, the specific requirements of each institution make it very difficult to suggest a generalized model and a solution algorithm far this problem. The purpose of this study is to design a system far scheduling courses at Bilkent University. This system utilizes both constraint programming and mathematical programming techniques. The problem is solved in three stages. The first two stages, in tandem, generate a course schedule using constraint programming techniques, and in the last stage classrooms are assigned to courses by means of a mixed integer programming model. The proposed system is validated by experimental runs using Bilkent University course offerings and classroom data from past semesters.Item Open Access Voltage island based heterogeneous NoC design through constraint programming(Pergamon Press, 2014) Demiriz, A.; Bagherzadeh, N.; Ozturk, O.This paper discusses heterogeneous Network-on-Chip (NoC) design from a Constraint Programming (CP) perspective and extends the formulation to solving Voltage-Frequency Island (VFI) problem. In general, VFI is a superior design alternative in terms of thermal constraints, power consumption as well as performance considerations. Given a Communication Task Graph (CTG) and subsequent task assignments for cores, cores are allocated to the best possible places on the chip in the first stage to minimize the overall communication cost among cores. We then solve the application scheduling problem to determine the optimum core types from a list of technological alternatives and to minimize the makespan. Moreover, an elegant CP model is proposed to solve VFI problem by mapping and grouping cores at the same time with scheduling the computation tasks as a limited capacity resource allocation model. The paper reports results based on real benchmark datasets from the literature.