| 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. |
