51 lines
2.3 KiB
Text
51 lines
2.3 KiB
Text
|
GENERAL INFORMATION:
|
||
|
|
||
|
The BARNES application implements the Barnes-Hut method to simulate the
|
||
|
interaction of a system of bodies (N-body problem). A general description
|
||
|
of the Barnes-Hut method can be found in:
|
||
|
|
||
|
Singh, J. P. Parallel Hierarchical N-body Methods and Their Implications
|
||
|
for Multiprocessors. PhD Thesis, Stanford University, February 1993.
|
||
|
|
||
|
The SPLASH-2 implementation allows for multiple particles to be stored in
|
||
|
each leaf cell of the space partition. A description of this feature
|
||
|
can be found in:
|
||
|
|
||
|
Holt, C. and Singh, J. P. Hierarchical N-Body Methods on Shared Address
|
||
|
Space Multiprocessors. SIAM Conference on Parallel Processing
|
||
|
for Scientific Computing, Feb 1995, to appear.
|
||
|
|
||
|
RUNNING THE PROGRAM:
|
||
|
|
||
|
To see how to run the program, please see the comment at the top of the
|
||
|
file code.C, or run the application with the "-h" command line option.
|
||
|
The input parameters should be placed in a file and redirected to standard
|
||
|
input. Of the twelve input parameters, the ones which would normally be
|
||
|
varied are the number of particles and the number of processors. If other
|
||
|
parameters are changed, these changes should be reported in any results
|
||
|
that are presented.
|
||
|
|
||
|
The only compile time option, -DQUADPOLE, controls the use of quadpole
|
||
|
interactions during the force computation. For the input parameters
|
||
|
provided, the -DQUADPOLE option should not be defined. The constant
|
||
|
MAX_BODIES_PER_LEAF defines the maximum number of particles per leaf
|
||
|
cell in the tree. This constant also affects the parameter "fleaves" in
|
||
|
the input file, which controls how many leaf cells space is allocated for.
|
||
|
The higher the value of MAX_BODIES_PER_LEAF, the lower fleaves should be.
|
||
|
Both these parameters should be kept at their default values for base
|
||
|
SPLASH-2 runs. If changes are made, they should be reported in any results
|
||
|
that are presented.
|
||
|
|
||
|
BASE PROBLEM SIZE:
|
||
|
|
||
|
The base problem size for an upto-64 processor machine is 16384 particles.
|
||
|
For this many particles, you can use the input file provided (and change
|
||
|
only the number of processors).
|
||
|
|
||
|
DATA DISTRIBUTION:
|
||
|
|
||
|
Our "POSSIBLE ENHANCEMENT" comments in the source code tell where one
|
||
|
might want to distribute data and how. Data distribution, however, does
|
||
|
not make much difference to performance on the Stanford DASH
|
||
|
multiprocessor.
|