By strictly separating reconfigurable logic from the host processor, current custom computing systems suffer from a significant communication bottleneck. In this paper, we describe Chimaera, a system that overcomes the communication bottleneck by integrating reconfigurable logic into the host processor itself. With direct access to the host processor’s register file, the system enables the creation of multi-operand instructions and a speculative execution model key to high-performance, general-purpose reconfigurable computing. Chimaera also supports multi-output functions and utilizes partial run-time reconfiguration to reduce reconfiguration time. Combined, the system can provide speedups of a factor of two or more for general-purpose computing, and speedups of 160 or more are possible for hand-mapped applications.

Software Pipelining is a loop scheduling technique that extracts parallelism from loops by overlapping the execution of several consecutive iterations. Most prior scheduling research has focused on achieving minimum execution time, without regarding register requirements. Most strategies tend to stretch operand lifetimes because they schedule some operations too early or too late. The paper presents a novel strategy that simultaneously schedules some operations late and other operations early, minimizing all the stretchable dependencies and therefore reducing the registers required by the loop. The key of this strategy is a pre-ordering phase that selects the order in which the operations will be scheduled. The results show that the method described in this paper performs better than other heuristic methods and almost as well as a linear programming method but requiring much less time to produce the schedules.

We propose a method to evaluate signs of 2 x 2 and 3 x 3 determinants with b-bit integer entries using only b and (b + 1)-bit arithmetic respectively. This algorithm has numerous applications in geometric computation and provides a general and practical approach to robustness. The algorithm has been implemented and experimental results show that it slows down the computing time by only a small factor with respect to floating-point calculation.

Distributed high-performance computing---so-called metacomputing---refers to the coordinated use of a pool of geographically distributed high-performance computers. The user's view of an ideal metacomputer is that of a powerful monolithic virtual machine. The implementor 's view, on the other hand, is that of a variety of interacting services implemented in a scalable and extensible manner. In this paper, we present MOL, the Metacomputer Online environment. In contrast to other metcomputing environments, MOL is not based on specific programming models or tools. It has rather been designed as an open, extensible software system comprising a variety of software modules, each of them specialized in serving one specific task such as resource scheduling, job control, task communication, task migration, user interface, and much more. All of these modules exist and are working. The main challenge in the design of MOL lies in the specification of suitable, generic interfaces for the effective ...

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This work deals with the problems caused by the high register requirements of software pipelined loops. The main contributions of this work are: * Register requirements of software pipelined loops are evaluated. * Several heuristics to perform register-constrained software pipelining are proposed * The effects of register requirements on performance under register constraints are evaluated * HRMS is proposed to perform software pipelining with resource constraints and reduced register requirements * Two new register file organizations are proposed to allow for a large number of registerse with low area cost and fast access time.

In this paper, we take an availability-centric view on quality of service (QoS) and propose a model and mechanisms for studying the effectiveness of realistic replication schemes on availability QoS for peer-to-peer (P2P) systems. We especially tackle the dynamic replica placement (RP) problem where our focus is on choosing dynamically the number and location of replicas while (1) meeting different availability QoS requirements for all individual peers and (2) taking the intermittent connectivity of peers explicitly into account. We model P2P systems as a dynamic stochastic graph in which the nodes go up and down depending on their assigned up probability. We develop some simple heuristic algorithms for solving the RP problem, which are fully distributed and adaptive. Through an event-driven simulation study we compare and evaluate the achieved availability QoS of the proposed RP algorithms. Simulation results show that (1) even simple heuristics can achieve reasonably high availability QoS, and (2) satisfying availability QoS requires more replicas than for only increasing the hit rate. 1.

This paper presents a novel software pipelining approach, which is called Swing Modulo Scheduling (SMS). It generates schedules that are near optimal in terms of initiation interval, register requirements and stage count. Swing Modulo Scheduling is a heuristic approach that has a low computational cost. This paper first describes the technique and evaluates it for the Perfect Club benchmark suite on a generic VLIW architecture. SMS is compared with other heuristic methods showing that it outperforms them in terms of the quality of the obtained schedules and compilation time. To further explore the effectiveness of SMS, the experience of incorporating it into a production quality compiler for the Equator MAP1000 processor is described; implementation issues are discussed as well as modifications and improvements to the original algorithm. Finally, experimental results from using a set of industrial multimedia applications are presented.

We describe a new exact-arithmetic approach to linear programming when the number of variables n is much larger than the number of constraints m (or vice versa). The algorithm is an implementation of the simplex method which combines exact (multiple precision) arithmetic with inexact (floating point) arithmetic, where the number of exact arithmetic operations is small and usually bounded by a function of min(n; m). Combining this with a "partial pricing" scheme (based on a result by Clarkson [8]) which is particularly tuned for the problems under consideration, we obtain a correct and practically efficient algorithm that even competes with the inexact state-of-the-art solver CPLEX 1 for small values of min(n; m) and and is far superior to methods that use exact arithmetic in any operation. 1 Introduction Linear Programming (LP) -- the problem of maximizing a linear objective function in n variables subject to m linear (in)equality constraints -- is the most prominent optimization ...

This paper addresses the problem of using three disc-shaped robots to manipulate a polygonal object in the plane in the presence of obstacles. The proposed approach is based on the computation of maximal discs (dubbed maximum independent capture discs, or MICaDs) where the robots can move independently while preventing the object from escaping their grasp. It is shown that, in the absence of obstacles, it is always possible to bring a polygonal object from any configuration to any other one with robot motions constrained to lie in a set of overlapping MICaDs. This approach is generalized to the case where obstacles are present by decomposing the corresponding motion planning task into (1) the construction of a collision-free path for a modified form of the object, and (2) the execution of this path by a sequence of simultaneous and independent robot motions within overlapping MICaDs. The proposed algorithm is guaranteed to generate a valid plan provided a collision-free path exists for the modified form of the object. It has been implemented and experiments with Nomadic Scout mobile robots are presented.