Name:FLY
Description:Fast Leveled ode for n-bodY simulations
Abstract:Cosmological simulations of galaxies and Large Scale structures formation have played a fundamental role in the study of the origin, formation and
evolution of the Universe. These studies improved enormously with the use of
supercomputers and parallel systems and, recently, grid based systems and Linux clusters.
FLY is a tree N-body parallel code that runs on a Linux Cluster using the
one side communication paradigm MPI-2. <br>
FLY is included in the Computer Physics Communication Program Library.
It makes possible to run a 64 Million particle simulation
in less than 15 minutes for each timestep, and its performance scales well with increasing number of processors.
<br>The application is now ported on the grid PI2S2/Cometa.<br>
This fact has lead us to propose FLY as a code to run very large N-Body simulations, up to more than $10^{9}$ particles
with the higher resolution of a pure tree code: a such a simulation will be run during the incoming few months.
<br><br>
<b>NEW ASPECTS:</b>
The porting of the application porting was made possible after a deep modification of the original code, which enabled the possibility of running test simulations and very big simulations with about one billion particles.
<br>The following points were developed:
<br>
1) I/O system. Originally the code was developed for a shared home environment. The grid system has not this feature,
so a great effort was done to rearrange all the I/O system with many intermediate files. All the maps of the original arrays where particles and tree structures are stored were re-organized and a deeply modification was done.
<br>
2)The performances with MPI-1 we obtained with a test procedure for FLY, gave us very high performances using this communication paradigm. A new version is available and based on this paradigm.
The algorithm itself was deeply modified : each processor has now a private sub-domain tree and receive external particles from other processors. It computes the “force component” that the sub-domain gives fo

Created:2010-05-01
Last updated:2010-05-01