Adaptive Cache-Oblivious All-to-All Operation

Modern processors rely on cache memories to reduce the latency of data accesses. Extensive cache misses would thus compromise the usefulness of the scheme. Cache-aware algorithms make use of the knowledge about the cache, such as the cache line size, L, and cache size, Z, to be cache efficient. However, careful tuning of these parameters for these algorithms is needed for different hardware platforms. Cache-oblivious (CO) algorithms were first introduced by Leiserson to work without the knowledge of the cache parameters mentioned earlier, but still achieve optimal work complexity and optimal cache complexity. Here we present CO algorithms for all-to-all operations (analogous to the cross-product operation). Its applications include Convolution, Polynomial Arithmetic, Multiple Sequence Alignment, N-Body Simulation, etc. Given two lists each with n elements, a naive implementation of all-to-all operation incurs O(n²/L) cache misses. Our CO version incurs only O(n²/L²√Z) cache misses. Preliminary experiments on Opteron 1.4GHz and MIPS 250MHz show that the CO implementation achieves two times faster. The profiling tool further confirms that the amount of cache misses is significantly lower. We also consider various situations where (a) the elements have non-uniform sizes, (b) an element cannot fit into the cache, (c) the lengths of the lists vary, and (d) an element is linked list. In addition, we study the extension to K-lists All-to-All Operation and its application. Finally, we will present the empirical results and compare with cache-aware algorithms.Singapore-MIT Alliance (SMA

Relaxing Routing Table to Alleviate Dynamism in P2P Systems

In dynamic P2P networks, nodes join and depart from the system frequently, which partially damages the predefined P2P structure, and impairs the system performance such as basic lookup functionality. Therefore stabilization process has to be done to restore the logical topology. This paper presents an approach to relax the requirement on routing tables to provide provably better stability than fixed structured P2P systems. We propose a relaxed Chord that keeps the O(logN) number of hops for greedy lookup, but it requires less stabilization overhead. It allows a tradeoff between lookup efficiency and structure flexibility without adding any overhead to the system. In the relaxed routing structure, each routing entry ("finger") of the node is allowed to vary within a set of values. Each node only needs to keep a certain number of fingers that point to nodes in its anchor set. This relaxation reduces the burden of state management of the node. The relaxed routing scheme provides an alternative structure other than randomized P2P and deterministic P2P, by relaxing on finger selection. It provides good flexibility and therefore extends the system functioning time.Singapore-MIT Alliance (SMA

Efficient Algorithms for Load Shuffling in Split-Platform AS/RS

We address the issue of shuffling loads in Automated Storage/Retrieval Systems (AS/RS) in this paper. The objective is to pre-sort the loads into any specified locations in order to minimize the response time of retrievals. 1D, 2D and 3D AS/RS racks have been designed in order to achieve the shuffling efficiently. The shuffling algorithms are described in detail. The response time of retrieval, the lower and upper bounds of energy consumption are also derived. Results of the analysis and numerical experiments show that the shuffling algorithms are quite efficient.Singapore-MIT Alliance (SMA

Hierarchical Multi-Bottleneck Classification Method And Its Application to DNA Microarray Expression Data

The recent development of DNA microarray technology is creating a wealth of gene expression data. Typically these datasets have high dimensionality and a lot of varieties. Analysis of DNA microarray expression data is a fast growing research area that interfaces various disciplines such as biology, biochemistry, computer science and statistics. It is concluded that clustering and classification techniques can be successfully employed to group genes based on the similarity of their expression patterns. In this paper, a hierarchical multi-bottleneck classification method is proposed, and it is applied to classify a publicly available gene microarray expression data of budding yeast Saccharomyces cerevisiae.Singapore-MIT Alliance (SMA

Provably Efficient Adaptive Scheduling for Parallel Jobs

Scheduling competing jobs on multiprocessors has always been an important issue for parallel and distributed systems. The challenge is to ensure global, system-wide efficiency while offering a level of fairness to user jobs. Various degrees of successes have been achieved over the years. However, few existing schemes address both efficiency and fairness over a wide range of work loads. Moreover, in order to obtain analytical results, most of them require prior information about jobs, which may be difficult to obtain in real applications. This paper presents two novel adaptive scheduling algorithms -- GRAD for centralized scheduling, and WRAD for distributed scheduling. Both GRAD and WRAD ensure fair allocation under all levels of workload, and they offer provable efficiency without requiring prior information of job's parallelism. Moreover, they provide effective control over the scheduling overhead and ensure efficient utilization of processors. To the best of our knowledge, they are the first non-clairvoyant scheduling algorithms that offer such guarantees. We also believe that our new approach of resource request-allotment protocol deserves further exploration. Specifically, both GRAD and WRAD are O(1)-competitive with respect to mean response time for batched jobs, and O(1)-competitive with respect to makespan for non-batched jobs with arbitrary release times. The simulation results show that, for non-batched jobs, the makespan produced by GRAD is no more than 1.39 times of the optimal on average and it never exceeds 4.5 times. For batched jobs, the mean response time produced by GRAD is no more than 2.37 times of the optimal on average, and it never exceeds 5.5 times.Singapore-MIT Alliance (SMA

IMPLEMENTING ASEAN STOCK TRADING LINKS: TACKLING THE INSTITUTIONAL CHALLENGES

Benefits of financial market integration across different economies have motivated a series of mergers and acquisitions, and electronic trading link-ups across regional financial markets. Drawing on institutional theory, we look beyond technological solutions to surface strategies in tackling the institutional challenges in the context of cross-border financial market integration. Through an interpretative case study of ASEAN Exchanges, we found that successful market integration requires the active lobbying of regulators to gain regulative legitimacy, peer socialization within the profession to attain normative legitimacy, and the reframing of mindsets through education, publicity and new symbolic artifacts to achieve cultural-cognitive legitimacy. Results highlight the importance for entrepreneurial focal actors to adopt an institutional lens and its respective strategies to enhance the success of technology implementation in a highly institutionalized context