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*windpar* may be used to compute an estimate of the potential
for speed-up of a particular Wind-US case when run in parallel mode.
The calculation is based on the likely number of grid points per
processor, as determined from the number of zones and the grid size in
each zone.
Grid sizes are read from a common grid (*.cgd*) or common flow
(*.cfl*) file.
It is assumed that each processor is equally powerful, and zonal
differences in solution procedure are not taken into account.

*Example*

Suppose we have the simple three-zone configuration shown below, with grid sizes 17 × 6, 33 × 11, and 17 × 11 in zones 1, 2, and 3, respectively.

Running *windpar* for this configuration gives the following
results.
Lines in slanted type are typed by the user.

%windpar***** windpar ***** Select the desired version from the following list. 0) END 1) windpar Single program automatically selected. windpar - Version 1.5 (last changed 2007/02/14 20:05:48) **************************************************************************** * Warning: This software contains technical data whose export is * * restricted by the Arms Export Control Act (Title 22, U.S.C., Sec 2751, * * et seq.) or Executive Order 12470. Violation of these export-control * * laws is subject to severe criminal penalties. Dissemination of this * * software is controlled under DoD Directive 5230.25 and AFI 61-204. * **************************************************************************** Please input CFL or CGD filenamecase4.cgdProc Speedup Proc Speedup Proc Speedup Proc Speedup 1 1.000 2 1.796 3 1.796 Maximum speedup attainable is a speedup of 1.796 on 2 processors with an efficiency of 89.807% Proc Eff. Proc Eff. Proc Eff. Proc Eff. 1 100.000 2 89.807 3 59.871

The speedup is defined as the total number of grid points in the problem, divided by the maximum number of grid points on any processor. The efficiency is then defined as the speedup divided by the number of processors, expressed as a percentage.

For this particular three-zone case, we have

Number of Processors |
| Points on Processor 1 |
| Points on Processor 2 |
| Points on Processor 3 |
| Speedup |
| Efficiency
| |
---|---|---|---|---|---|---|---|---|---|---|---|

1 | 652 | - | - | 1.000 | 100% | ||||||

2 | 363 | 289 | - | 1.796 | 89.807% | ||||||

3 | 363 | 187 | 102 | 1.796 | 59.871% |

Thus, the best scenario for this case is to run on two processors. Because the total number of grid points in zones 1 and 3 combined (289) is less than the total number in zone 2 (363), the maximum speedup is the same whether two or three processors are used.

Last updated 7 Aug 2007