195611449
Scheduling tasks in multiprocessor systems using evolutionary strategies
Scheduling tasks in multiprocessor systems is a difficult problem. The paper describes a method based upon evolutionary strategies (using genetic algorithms) to aid in finding good task assignments. The technique is illustrated by scheduling a digital signal processing algorithm on a two processor distributed system.<<ETX>>
11054622
Classification using Efficient LU Decomposition in Sensornets
We consider the popular application of detection, classification and tracking and their feasibility in resource constrained sensornets. We concentrate on the classification aspect, by decomposing the complex, computationally intensive signal processing Maximum-APosterior (MAP) classifier into simpler computationally and communicationally load balanced procedures, using a clustering approach. LU decomposition is an efficient approach for computing the inverse of covariance matrices required in the MAP classifier. We thus explore feasibility of LU decomposition in sensornets. We present power-aware and load balanced techniques for LU decomposition of the covariance matrices in sensornets alongwith their analytical and power consumption analyses.
5331854
On the Scalable Computation of Large Sets of Integrals
We consider efficient strategies for the parallel and distributed computation of large sets of multivariate integrals. These arise in many applications such as computational chemistry, high energy physics and finite element problems. We use a hierarchical architecture which is highly scalable and allows parallelization not only at the domain level but also at the integral level. We present experimental results on a family of parametrized integrals and show that our approach leads to an efficient scalable load balanced algorithm. The methods are easily applicable to other areas where a large number of problems need to be solved efficiently on a parallel and distributed system.
3246043
Parallel organization and performance of an information system
This paper investigates a directory structure, based on an M-B-T directory, that provides for parallel retrieval of information with low communication overhead. An information system of documents is assumed. It is compatible with current automatic retrieval and query processing techniques. It is also compatible with any organization of the documents. Weights that are assigned to keywords can be included in the directory with the keywords at no additional cost. In addition, it provides for indexing a secondary keyword within a primary keyword with no additional cost. Given a p-processor massively parallel computer, our organization allows a maximum of p retrievals to be performed concurrently and thus achieves an approximate speed up of p in the best case. The new, revised organization improves on previous work. An eecient parallel searching algorithm and its performance is also discussed.
32901959
Efficient embeddings of ternary trees into hypercubes
In this paper we present efficient graph embeddings for complete k-ary trees into boolean hypercubes. In particular, we describe an efficient embedding of a complete ternary tree (k = 3) of height h into a hypercube, which achieves dilation 3 and expansion Θ(1.0104...h). The previously best-known result is dilation 2 and expansion Θ(1.333...h). Our embedding achieves exponentially better expansion at the cost of an increase of 1 in the dilation. We also describe efficient embeddings of k-ary trees into hypercubes when k = 2p * 3q for some p, q > 0 such that the embeddings achieve small constant dilation.
155165
Multivariate Integration on Hypercubic and Mesh Networks
Abstract We analyze a class of adaptive algorithms for integration over N-dimensional hyper-rectangular or simplical regions, on distributed systems. An adaptive algorithm attempts to achieve the requested accuracy by refining the subdivision of the integration region, thus allowing for a concentration of subdivisions near singularities. At the subdivision of a region, the error behaves according to a prescribed model, relating the error of the parent region to that of its children. The analysis can also be applied to problems in other areas, as long as the task selection is based on a priority function which behaves according to a suitable model. Using an efficient management of the subregions, we show that an O (p/ log p) speedup can be achieved on a p-processor hypercubic network, such as shuffle exchange, butterfly and hypercube. Furthermore, a speedup of O ( p ) can be achieved on a p × p mesh network. We also show that our algorithms compare favorably with well-known dynamic load balancing strategies.
17323833
Verification of scheduling in the presence of loops using uninterpreted symbolic simulation
We propose a novel procedure based on uninterpreted symbolic simulation for checking the scheduling step in high-level synthesis. The primary task in scheduling is the assignment of time steps or, equivalently, states to operations. Various transformations like operation reordering and loop unrolling may be performed in the process to meet the optimization criteria. The contribution of our proposal lied in its ability to efficiently handle loops and a wide range of loop transformations performed during scheduling. Our algorithm is based on loop invariant extraction using a combination of uninterpreted symbolic simulation and induction techniques. In spite of its wide scope, our procedure is relatively complete and practical. This work is a part of our effort to provide a suite of techniques for verifying the various steps involved in the high-level synthesis process. It is being implemented in an in-house verification system for checking equivalence of designs generated from high-level specifications through successive refinements. We present case studies to demonstrate the applicability of our approach. These case studies consist of examples where equivalence cannot be established using conventional FSM-based methods. By providing a viable automated equivalence checking technique for such examples, we improve on the state of the art.
24549782
Adaptive Fault Tolerant Hospital Resource Scheduling
In a distributed hospital system, different hospitals should collaborate among themselves for sharing their resources to provide better and faster service to the patients. We address the distributed hospital resource scheduling problem and apply the Generalized Partial Global Planning (GPGP) approach used for multiagent systems for the same. An adaptive coordination mechanism based on the contract net protocol is proposed to support inter-hospital collaboration. We have performed simulation studies and the experimental results show that our coordination mechanism performs better than commonly used schemes. Fault handling mechanisms are presented so that the system continues to provide service even in the presence of faults. The proposed approach is applicable in contexts other than the distributed hospital system as well.
14465668
The economics of network management
Why are pricing issues the key to infrastructure investment and future growth of the Internet? The Economics of network management I t is not surprising that researchers in network technology are utilizing ideas from the field of economics since it provides the conceptual understanding of underlying constructs such as usage and resource allocation. Proper resource allocation plays a key role in improving network performance. There are two primary approaches to economic resource allocation: quantity limits, and pricing. The former has the advantage of low accounting costs. However, it requires central administration and, for network users wishing to purchase more quantity than allocated, a pricing schedule has to be developed. The pricing approach does not enforce any quantity limits. Instead, users self-select the quantity they are willing to purchase at prevailing prices. The pricing approach decentralizes the resource allocation problem but has higher accounting costs since usage needs to be monitored and billed. The role of pricing as a resource allocation mechanism will be examined here, since central administration of quotas would be difficult in a global network. Furthermore, a pricing mechanism may still be needed to meet user demands in e-commerce. While the short-term role of economic pricing is to manage the network resources more efficiently, in the long run it could play an important role in the design of new network protocols. For example, new technological developments with priority classes in the IPv6 Internet protocol [3] will present the challenge of defining an economic basis for priority allocation. The Internet traffic-pricing problem for e-commerce subsumes traditional telecommuni-cation pricing policies and is much more complex. Traditional telecommunication systems offer a single quality level for their services on a given type of network, for example, the ability to carry voice data at a desired rate on a telephone network. However, in e-commerce there is a rich collection of services that require different levels of service quality over the same data communication network. For example, during a telnet session a user requires a high-speed and low-volume data transfer for real-time interaction with a server. On the other hand, a video conference needs clarity and coordination in picture and sound, necessitating a much more complex set of service quality attributes, such as synchronization of information sent via different interoperable applications (video, audio, and text). In addition, audio and video applications require high-volume and high-speed transfers with low variability in data transfer rates. These …
25366029
Formal hardware verification methods: A survey
Growing advances in VLSI technology have led to an increased level of complexity in current hardware systems. Late detection of design errors typically results in higher costs due to the associated time delay as well as loss of production. Thus it is important that hardware designs be free of errors. Formal verification has become an increasingly important technique towards establishing the correctness of hardware designs. In this article we survey the research that has been done in this area, with an emphasis on more recent trends. We present a classification framework for the various methods, based on the forms of the specification, the implementation, and the proff method. This framework enables us to better highlight the relationships and interactions between seemingly different approaches.
18052775
Pricing of risk for loss guaranteed intra-domain internet service contracts
The Internet today offers primarily a best-effort service. Research and technology development efforts are currently underway to allow provisioning of better than best-effort Quality of Service (QoS) assurances. The residual uncertainty in QoS can be managed using pricing strategies. In this article, we develop a spot pricing framework for intra-domain expected bandwidth contracts with loss-based QoS guarantees. The framework builds on a nonlinear pricing scheme for cost recovery from earlier work and extends it to price risk. A utility-based options pricing approach is developed to account for the uncertainties in delivering loss guarantees. Application of options pricing techniques in Internet services provides a mechanism for fair risk sharing between the provider and the customer, and may be extended to price other uncertainties in QoS guarantees.