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fix_balance.cpp
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Fri, Jun 7, 09:01

fix_balance.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
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.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "string.h"
#include "stdlib.h"
#include "fix_balance.h"
#include "balance.h"
#include "update.h"
#include "domain.h"
#include "atom.h"
#include "comm.h"
#include "irregular.h"
#include "force.h"
#include "kspace.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixBalance::FixBalance(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 7) error->all(FLERR,"Illegal fix balance command");
box_change_domain = 1;
scalar_flag = 1;
extscalar = 0;
vector_flag = 1;
size_vector = 3;
extvector = 0;
global_freq = 1;
// parse arguments
int dimension = domain->dimension;
nevery = force->inumeric(FLERR,arg[3]);
if (strlen(arg[4]) > 3) error->all(FLERR,"Illegal fix balance command");
strcpy(bstr,arg[4]);
nitermax = force->inumeric(FLERR,arg[5]);
thresh = force->numeric(FLERR,arg[6]);
if (nevery < 0 || nitermax <= 0 || thresh < 1.0)
error->all(FLERR,"Illegal fix balance command");
int blen = strlen(bstr);
for (int i = 0; i < blen; i++) {
if (bstr[i] != 'x' && bstr[i] != 'y' && bstr[i] != 'z')
error->all(FLERR,"Fix balance string is invalid");
if (bstr[i] == 'z' && dimension == 2)
error->all(FLERR,"Fix balance string is invalid for 2d simulation");
for (int j = i+1; j < blen; j++)
if (bstr[i] == bstr[j])
error->all(FLERR,"Fix balance string is invalid");
}
// optional args
int outarg = 0;
fp = NULL;
int iarg = 7;
while (iarg < narg) {
if (strcmp(arg[iarg],"out") == 0) {
if (iarg+2 > narg) error->all(FLERR,"Illegal fix balance command");
outarg = iarg+1;
iarg += 2;
} else error->all(FLERR,"Illegal fix balance command");
}
// create instance of Balance class and initialize it with params
// create instance of Irregular class
balance = new Balance(lmp);
balance->dynamic_setup(bstr,nitermax,thresh);
irregular = new Irregular(lmp);
// output file
if (outarg && comm->me == 0) {
fp = fopen(arg[outarg],"w");
if (fp == NULL) error->one(FLERR,"Cannot open fix balance output file");
}
// only force reneighboring if nevery > 0
if (nevery) force_reneighbor = 1;
// compute initial outputs
imbfinal = imbprev = balance->imbalance_nlocal(maxperproc);
itercount = 0;
pending = 0;
}
/* ---------------------------------------------------------------------- */
FixBalance::~FixBalance()
{
if (fp) fclose(fp);
delete balance;
delete irregular;
}
/* ---------------------------------------------------------------------- */
int FixBalance::setmask()
{
int mask = 0;
mask |= PRE_EXCHANGE;
mask |= PRE_NEIGHBOR;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixBalance::init()
{
if (force->kspace) kspace_flag = 1;
else kspace_flag = 0;
}
/* ---------------------------------------------------------------------- */
void FixBalance::setup(int vflag)
{
// compute final imbalance factor if setup_pre_exchange() invoked balancer
// this is called at end of run setup, before output
pre_neighbor();
}
/* ---------------------------------------------------------------------- */
void FixBalance::setup_pre_exchange()
{
// insure atoms are in current box & update box via shrink-wrap
// no exchange() since doesn't matter if atoms are assigned to correct procs
if (domain->triclinic) domain->x2lamda(atom->nlocal);
domain->pbc();
domain->reset_box();
if (domain->triclinic) domain->lamda2x(atom->nlocal);
// perform a rebalance if threshhold exceeded
imbnow = balance->imbalance_nlocal(maxperproc);
if (imbnow > thresh) rebalance();
// next_reneighbor = next time to force reneighboring
if (nevery) next_reneighbor = (update->ntimestep/nevery)*nevery + nevery;
}
/* ----------------------------------------------------------------------
perform dynamic load balancing
------------------------------------------------------------------------- */
void FixBalance::pre_exchange()
{
// return if not a rebalance timestep
if (nevery && update->ntimestep < next_reneighbor) return;
// insure atoms are in current box & update box via shrink-wrap
// no exchange() since doesn't matter if atoms are assigned to correct procs
if (domain->triclinic) domain->x2lamda(atom->nlocal);
domain->pbc();
domain->reset_box();
if (domain->triclinic) domain->lamda2x(atom->nlocal);
// return if imbalance < threshhold
imbnow = balance->imbalance_nlocal(maxperproc);
if (imbnow <= thresh) {
if (nevery) next_reneighbor = (update->ntimestep/nevery)*nevery + nevery;
return;
}
rebalance();
// next timestep to rebalance
if (nevery) next_reneighbor = (update->ntimestep/nevery)*nevery + nevery;
}
/* ----------------------------------------------------------------------
compute final imbalance factor based on nlocal after comm->exchange()
only do this if rebalancing just occured
------------------------------------------------------------------------- */
void FixBalance::pre_neighbor()
{
if (!pending) return;
imbfinal = balance->imbalance_nlocal(maxperproc);
pending = 0;
}
/* ----------------------------------------------------------------------
perform dynamic load balancing
------------------------------------------------------------------------- */
void FixBalance::rebalance()
{
imbprev = imbnow;
itercount = balance->dynamic();
// output of final result
if (fp) balance->dumpout(update->ntimestep,fp);
// reset comm->uniform flag
comm->uniform = 0;
// reset proc sub-domains
if (domain->triclinic) domain->set_lamda_box();
domain->set_local_box();
// if splits moved further than neighboring processor
// move atoms to new processors via irregular()
// only needed if migrate_check() says an atom moves to far,
// else allow caller's comm->exchange() to do it
if (domain->triclinic) domain->x2lamda(atom->nlocal);
if (irregular->migrate_check()) irregular->migrate_atoms();
if (domain->triclinic) domain->lamda2x(atom->nlocal);
// invoke KSpace setup_grid() to adjust to new proc sub-domains
if (kspace_flag) force->kspace->setup_grid();
// pending triggers pre_neighbor() to compute final imbalance factor
// can only be done after atoms migrate in caller's comm->exchange()
pending = 1;
}
/* ----------------------------------------------------------------------
return imbalance factor after last rebalance
------------------------------------------------------------------------- */
double FixBalance::compute_scalar()
{
return imbfinal;
}
/* ----------------------------------------------------------------------
return stats for last rebalance
------------------------------------------------------------------------- */
double FixBalance::compute_vector(int i)
{
if (i == 0) return (double) maxperproc;
if (i == 1) return (double) itercount;
return imbprev;
}
/* ----------------------------------------------------------------------
return # of bytes of allocated memory
------------------------------------------------------------------------- */
double FixBalance::memory_usage()
{
double bytes = irregular->memory_usage();
return bytes;
}

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