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This includes pull request #130 by Iain Bethune (EPCC) with additional modifications requested by Steve P. In contrast to Iain's implementation, there is no modification to the group command, but the group specific weight factors are provided as command line arguments to the balance and fix balance commands instead. Here is the original description: This feature branch introduces the concept of particle weighting, so instead of balancing the number of particles per sub-domain instead particles are weighted by a user-defined load_factor. The load_factor is added as a new style in the group command, so that the weights can be applied to logically grouped sets of atoms. The default load_factor is 1.0 so if the user does not specify anything the existing load balance behaviour is maintained. This is especially useful for systems when nlocal is not proportional to the workload, for example hybrid pair_styles where some pair interactions are more computationally intensive, and for RESPA runs with high timestep ratios. Increasing the load_factor for particles involved in more expensive or more frequent operations improves performance. In my tests (atomistic BPTI in coarse-grained water, with RESPA ratios up to 1:8) I get significant speedups over the current load balancer: 1fs/4fs on 24 cores: the default gives a 1% speedup, with load_factor 2.5 for the solute, an 11% speedup is obtained 1fs/8fs on 72 cores: the default fives a 23% speedup, with load_factor 4.0 I get 103% (more than twice as fast!) The implementation works for both shift and rcb - actually for RCB it makes use of the existing (but unused) wt parameter and for shift, the number of local atoms is replaced by a weighted count. The actual load balancing algorithms are unchanged, just the metric that is balanced.
This is the LAMMPS software package. LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel Simulator. Copyright (2003) Sandia Corporation. Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains certain rights in this software. This software is distributed under the GNU General Public License. ---------------------------------------------------------------------- LAMMPS is a classical molecular dynamics simulation code designed to run efficiently on parallel computers. It was developed at Sandia National Laboratories, a US Department of Energy facility, with funding from the DOE. It is an open-source code, distributed freely under the terms of the GNU Public License (GPL). The primary author of the code is Steve Plimpton, who can be emailed at sjplimp@sandia.gov. The LAMMPS WWW Site at lammps.sandia.gov has more information about the code and its uses. The LAMMPS distribution includes the following files and directories: README this file LICENSE the GNU General Public License (GPL) bench benchmark problems couple code coupling examples using LAMMPS as a library doc documentation examples simple test problems lib libraries LAMMPS can be linked with potentials interatomic potential files python Python wrapper on LAMMPS as a library src source files tools pre- and post-processing tools Point your browser at any of these files to get started: doc/Manual.html the LAMMPS manual doc/Section_intro.html hi-level introduction to LAMMPS doc/Section_start.html how to build and use LAMMPS doc/Developer.pdf LAMMPS developer guide