127 lines
3.7 KiB
C++
127 lines
3.7 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://www.lammps.org/
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LAMMPS Development team: developers@lammps.org, Sandia National Laboratories
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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// example of how a calling program can invoke
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// multiple instances of LAMMPS, each on a subset of procs,
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// and have each of them perform a different run, and collect output info
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// Syntax: mpirun -np P multiple N in.lammps T Tdelta
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// P = # of total procs to run the driver program on
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// N = # of instances of LAMMPS to create, P must be divisible by N
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// in.lammps = LAMMPS input script,
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// which takes "t" as a temperature variable
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// T = baseline temperature
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// Tdelta = incremental temperature for each of N runs
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// See README for compilation instructions
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#include <mpi.h>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#define LAMMPS_LIB_MPI // to make lammps_open() visible
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#include "library.h"
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int main(int narg, char **arg)
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{
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// setup MPI and various communicators
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// driver runs on all procs in MPI_COMM_WORLD
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// comm_lammps only has 1st P procs (could be all or any subset)
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MPI_Init(&narg,&arg);
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if (narg != 5) {
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printf("Syntax: multiple N in.lammps T Tdelta\n");
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exit(1);
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}
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int me,nprocs;
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MPI_Comm_rank(MPI_COMM_WORLD,&me);
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MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
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int ninstance = atoi(arg[1]);
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if (nprocs % ninstance) {
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if (me == 0)
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printf("ERROR: Total procs must be divisble by N\n");
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MPI_Abort(MPI_COMM_WORLD,1);
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}
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char *infile = arg[2];
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double temperature = atof(arg[3]);
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double tdelta = atof(arg[4]);
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// create one communicator per instancem each with P/N procs
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int instance = me*ninstance / nprocs;
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MPI_Comm comm_lammps;
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MPI_Comm_split(MPI_COMM_WORLD,instance,0,&comm_lammps);
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// each instance: unique screen file, log file, temperature
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char str1[32],str2[32],str3[32];
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char **lmparg = new char*[8];
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lmparg[0] = (char *) "LAMMPS"; // required placeholder for program name
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lmparg[1] = (char *) "-screen";
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sprintf(str1,"screen.%d",instance);
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lmparg[2] = str1;
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lmparg[3] = (char *) "-log";
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sprintf(str2,"log.lammps.%d",instance);
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lmparg[4] = str2;
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lmparg[5] = (char *) "-var";
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lmparg[6] = (char *) "t";
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sprintf(str3,"%g",temperature + instance*tdelta);
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lmparg[7] = str3;
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// create N instances of LAMMPS
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void *lmp = lammps_open(8,lmparg,comm_lammps,NULL);
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delete [] lmparg;
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// run input script thru all instances of LAMMPS
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lammps_file(lmp,infile);
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// query final temperature and print result for each instance
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double *ptr = (double *)
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lammps_extract_compute(lmp,"thermo_temp",LMP_STYLE_GLOBAL,LMP_TYPE_SCALAR);
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double finaltemp = *ptr;
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double *temps = new double[ninstance];
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for (int i = 0; i < ninstance; i++) temps[i] = 0.0;
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int me_lammps;
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MPI_Comm_rank(comm_lammps,&me_lammps);
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if (me_lammps == 0) temps[instance] = finaltemp;
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double *alltemps = new double[ninstance];
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MPI_Allreduce(temps,alltemps,ninstance,MPI_DOUBLE,MPI_SUM,MPI_COMM_WORLD);
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if (me == 0)
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for (int i = 0; i < ninstance; i++)
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printf("Instance %d, final temp = %g\n",i+1,alltemps[i]);
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delete [] temps;
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delete [] alltemps;
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// delete LAMMPS instances
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lammps_close(lmp);
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// close down MPI
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MPI_Comm_free(&comm_lammps);
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MPI_Finalize();
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}
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