Browsing by Subject "Multicomputer"

Now showing 1 - 3 of 3

Open Access
Efficient fast hartley transform algorithms for hypercube-connected multicomputers
(IEEE, 1995) Aykanat, Cevdet; Derviş, A.
Although fast Hartley transform (FHT) provides efficient spectral analysis of real discrete signals, the literature that addresses the parallelization of FHT is extremely rare. FHT is a real transformation and does not necessitate any complex arithmetics. On the other hand, FHT algorithm has an irregular computational structure which makes efficient parallelization harder. In this paper, we propose a efficient restructuring for the sequential FHT algorithm which brings regularity and symmetry to the computational structure of the FHT. Then, we propose an efficient parallel FHT algorithm for medium-to-coarse grain hypercube multicomputers by introducing a dynamic mapping scheme for the restructured FHT. The proposed parallel algorithm achieves perfect load-balance, minimizes both the number and volume of concurrent communications, allows only nearest-neighbor communications and achieves in-place computation and communication. The proposed algorithm is implemented on a 32-node iPSC/21 hypercube multicomputer. High-efficiency values are obtained even for small size FHT problems. © 1995 IEEE
Open Access
Efficient overlapped FFT algorithms for hypercube-connected multicomputers
(1994) Aykanat, Cevdet; Dervis, A.
In this work, we propose parallel FFT algorithms, for medium-to-coarse grain hypercube-connected multicomputers, which are more elegant and efficient than the existing ones. The proposed algorithms achieve perfect load-balance for the efficient simplified-butterfly scheme, minimize the communication overhead by decreasing both the number and the volume of concurrent communications. Communication and computation cannot be overlapped easily due to the strong data dependencies in the FFT algorithm. In this paper, we propose a restructuring for the FFT algorithm which enables overlapping each communication with one fifth of the local computations involved in a stage. Two of the proposed parallel FET algorithms achieve overlapping by exploiting this restructuring while using the efficient table-lookup scheme for complex coefficients. The proposed algorithms are implemented on an Intel’s 32-node iPSC/2 hypercube multicomputer. High efficiency values are obtained even for small size FFT problems. © 1994, Taylor & Francis Group, LLC. All rights reserved.
Open Access
Parallel maze routing algorithms on a hypercube multicomputer
(1991) Kurç, Tahsin Mertefe
Global routing phase is a time consuming task in VLSI layout. In global routing phase of the layout problem, the overall objective is to realize all the net interconnections using shortest paths. Efficient heuristics are used for the global routing phase. However, clue to the assumptions and constraints they impose, heuristics may fail to find a path for a net even if one exists. Re-routing is required for such nets. This re-routing phase requires the exhaustive search of the wiring area. Lee’s maze routing algorithm and Lee type maze routing algorithms are exhaustive search algorithms used in re-routing phase. These algorithms are computationally expensive algorithms and consume large amounts of computer time for large grid sizes. Hence, these algorithms are good candidates for parallelization. Also, these algorithms require large memory space to hold the wiring grid. Therefore, the effective parallelization of these algorithms require the partitioning of the computations and the grid among the processors. Hence, these algorithms can be parallelized on distributed-memory message passing multiprocessors (multicomputers). In this work, efficient parallel Lee type maze routing algorithms are developed for hypercube-connected multi computers. These algorithms are implemented on an Intel’s iPSC/2 hypercube multicomputer.