Basic nbody gravitational simulation program in c++ Comparison of just CPU, using openmpi to calculate forces in parallel, and using opencl GPU to evolve steps in parallel.
Using 2-3 processes gets a ~2x speedup over non-parallelized versions, for example, for 10k particles over 1000 steps, the original version takes about 50 minutes, versus the 21 minutes of the open-mpi version.
Running base version:
./nbody 1000 0.01 < InputFiles/i1000.in > outA1000.out
Steps to iterate: 1000, dt: 0.01
Reading input...
Generating 1000 bodies...
Done reading file.SIMULATION BEGIN
Simulating 1000 bodies for 1000 steps, using dt = 0.01
On Step 147/1000 - Time Spent: 5.01023s, Time left: ~29s
On Step 292/1000 - Time Spent: 10.0281s, Time left: ~24s
On Step 437/1000 - Time Spent: 15.0409s, Time left: ~19s
On Step 580/1000 - Time Spent: 20.0654s, Time left: ~14s
On Step 724/1000 - Time Spent: 25.0883s, Time left: ~9s
On Step 868/1000 - Time Spent: 30.1039s, Time left: ~4s
SIMULATION END
Simulation completed in 34.6856 seconds.
Running with open-mpi:
sudo mpirun -np 8 nbody_openmpi 1000 0.01 < InputFiles/i1000.in > outB1000.out
Steps to iterate: 1000, dt: 0.01
Reading input...
Generating 1000 bodies...
Done reading file.
SIMULATION BEGIN
Simulating 1000 bodies for 1000 steps, using dt = 0.01
On Step 236/1000 - Time Spent: 5.00299s, Time left: ~16s
On Step 460/1000 - Time Spent: 10.0161s, Time left: ~11s
On Step 654/1000 - Time Spent: 15.0183s, Time left: ~7s
On Step 827/1000 - Time Spent: 20.0226s, Time left: ~4s
SIMULATION END
Simulation completed in 24.7905 seconds.
Running with open-cl:
./nbody_opencl 1000 0.01 < InputFiles/i1000.in > out_cl_1000.out
Steps to iterate: 1000, dt: 0.01
Reading input...
Generating 1000 bodies...
Done reading file.SIMULATION BEGIN
Simulating 1000 bodies for 1000 steps, using dt = 0.01
On Step 463/1000 - Time Spent: 5.00111s, Time left: ~5s
On Step 942/1000 - Time Spent: 10.0075s, Time left: ~0s
SIMULATION END
Simulation completed in 10.6247 seconds.
To compile normal version: make
To run: nbody.exe STEPS DT < INPUTFILE > OUTPUTFILE
Example: nbody.exe 1000 0.01 < InputFiles/testInput > testOutput.out
Nov 16, 2014:
Matlab:
