Interprocessor communication and multitasking

1995 ◽  
Vol 05 (03) ◽  
pp. 331-341 ◽  
Author(s):  
MICHAEL G. NORMAN ◽  
SUSANNA PELAGATTI ◽  
PETER THANISCH

We show the NP-Completeness of two processor scheduling with tasks of execution time 1 or 2 units and unit interprocessor communication latency. We develop a model of scheduling in the presence of communication contention, and show the NP-Completeness of two processor scheduling with unit execution time tasks in our model.


2015 ◽  
Vol 61 (8) ◽  
pp. 374-382
Author(s):  
Stefan Waldherr ◽  
Sigrid Knust ◽  
Stefan Aust

1993 ◽  
Vol 83 (5) ◽  
pp. 1345-1354
Author(s):  
Quingbo Liao ◽  
George A. McMechan

Abstract Two pseudo-spectral implementations of 2-D viscoacoustic modeling are developed in a distributed-memory multi-processor computing environment. The first involves simultaneous computation of the response of one model to many source locations and, as it requires no interprocessor communication, is perfectly parallel. The second involves computation of the response, to one source, of a large model that is distributed across all processors. In the latter, local rather than global, Fourier transforms are used to minimize interprocessor communication and to eliminate the need for matrix transposition. In both algorithms, absorbing boundaries are defined as zones of decreased Q as part of the model, and so require no extra computation. An empirical method of determining sets of relaxation times for a broad range of Q values eliminates the need for iterative fitting of Q-frequency curves.


1995 ◽  
Vol 21 (5) ◽  
pp. 753-769 ◽  
Author(s):  
Shuichi Sakai ◽  
Yuetsu Kodama ◽  
Mitsuhisa Sato ◽  
Andrew Shaw ◽  
Hiroshi Matsuoka ◽  
...  

Author(s):  
Cristian Ianculescu ◽  
Lonny L. Thompson

Parallel iterative methods for fast solution of large-scale acoustic radiation and scattering problems are developed using exact Dirichlet-to-Neumann (DtN), nonreflecting boundaries. A separable elliptic nonreflecting boundary is used to efficiently model unbounded regions surrounding elongated structures. We exploit the special structure of the non-local DtN map as a low-rank update of the system matrix to efficiently compute the matrix-by-vector products found in Krylov subspace based iterative methods. For the complex non-hermitian matrices resulting from the Helmholtz equation, we use a distributed-memory parallel BICG-STAB iterative method in conjunction with a parallel Jacobi preconditioner. Domain decomposition with interface minimization was performed to ensure optimal interprocessor communication. For the architectures tested, and using the MPICH version of MPI, we show that when implemented as a low-rank update, the non-local character of the DtN map does not signicantly decrease the scale up and parallel eciency versus a purely approximate local boundary condition.


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