Main Title |
Optimizing a Photochemical Air Quality Model Gas-Phase Chemistry Solver for Parallel Processing. |
Author |
Cheung, W. ;
Young, J. O. ;
Davis, E. W. ;
|
CORP Author |
North Carolina State Univ. at Raleigh. Dept. of Electrical and Computer Engineering.;Environmental Protection Agency, Research Triangle Park, NC. National Exposure Research Lab. |
Publisher |
1997 |
Year Published |
1997 |
Report Number |
EPA-R-822076-01-2; EPA/600/A-97/017; |
Stock Number |
PB97-192918 |
Additional Subjects |
Photochemistry ;
Parallel processing(Computers) ;
Computational grids ;
Air pollution dispersion ;
Photochemical reactions ;
Environmental transport ;
Euler equations of models ;
Optimization ;
Mathematical models ;
Computerized simulation ;
Algorithms ;
QSSA(Quasi-Steady State Approximation) ;
Air Quality Model
|
Internet Access |
|
Holdings |
Library |
Call Number |
Additional Info |
Location |
Last Modified |
Checkout Status |
NTIS |
PB97-192918 |
Some EPA libraries have a fiche copy filed under the call number shown. |
|
07/26/2022 |
|
Collation |
13p |
Abstract |
In a testbed model based on EPA's Regional Oxidant Model, the Quasi-steady State Approximation (QSSA) gas-phase chemistry solver dominates the computation, which is typical of Eulerian grid cell air quality models. We report results from optimizing the testbed solver on a Cray T3D parallel system. We use a simple processor mapping to assign a block to grid cells to each T3D processing element (PE). To minimize execution time, programming optimization techniques, such as cache collision avoidance and loop unrolling, have been applied. Proper application of such techniques has a significant effect on performance, leading to improve speedup as compared with simply relying ng on optimizing compilers. PEs become idle while remaining Pes complete their tasks within a simulation time step. Based on experience with optimizing the QSSA on Cray vector supercomputers, a dynamic task allocation approach to deal with local imbalance is described and performance results are given. |
Supplementary Notes |
Sponsored by Environmental Protection Agency, Research Triangle Park, NC. National Exposure Research Lab. |
Availability Notes |
Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)321-8547; and email at orders@ntis.fedworld.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA. |
NTIS Title Notes |
Conference paper, FY 97. |
Category Codes |
68A; 99E |
NTIS Prices |
PC A03/MF A01 |
Primary Description |
600/09 |
Document Type |
NT |
Cataloging Source |
NTIS/MT |
Control Number |
731601600 |
Origin |
NTIS |
Type |
CAT |