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universe.cpp
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Fri, May 24, 14:51

universe.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 "mpi.h"
#include "stdlib.h"
#include "string.h"
#include "stdio.h"
#include "universe.h"
#include "version.h"
#include "error.h"
#include "memory.h"
using namespace LAMMPS_NS;
#define MAXLINE 256
/* ----------------------------------------------------------------------
create & initialize the universe of processors in communicator
------------------------------------------------------------------------- */
Universe::Universe(LAMMPS *lmp, MPI_Comm communicator) : Pointers(lmp)
{
version = (char *) LAMMPS_VERSION;
uworld = uorig = communicator;
MPI_Comm_rank(uworld,&me);
MPI_Comm_size(uworld,&nprocs);
uscreen = stdout;
ulogfile = NULL;
existflag = 0;
nworlds = 0;
procs_per_world = NULL;
root_proc = NULL;
memory->create(uni2orig,nprocs,"universe:uni2orig");
for (int i = 0; i < nprocs; i++) uni2orig[i] = i;
}
/* ---------------------------------------------------------------------- */
Universe::~Universe()
{
if (uworld != uorig) MPI_Comm_free(&uworld);
memory->destroy(procs_per_world);
memory->destroy(root_proc);
memory->destroy(uni2orig);
}
/* ----------------------------------------------------------------------
reorder universe processors
create uni2orig as inverse mapping
re-create uworld communicator with new ordering via Comm_split()
style = "nth", arg = N
move every Nth proc to end of rankings
style = "custom", arg = filename
file has nprocs lines with I J
I = universe proc ID in original communicator uorig
J = universe proc ID in reordered communicator uworld
------------------------------------------------------------------------- */
void Universe::reorder(char *style, char *arg)
{
char line[MAXLINE];
if (uworld != uorig) MPI_Comm_free(&uworld);
if (strcmp(style,"nth") == 0) {
int n = atoi(arg);
if (n <= 0)
error->universe_all(FLERR,"Invalid -reorder N value");
if (nprocs % n)
error->universe_all(FLERR,"Nprocs not a multiple of N for -reorder");
for (int i = 0; i < nprocs; i++) {
if (i < (n-1)*nprocs/n) uni2orig[i] = i/(n-1) * n + (i % (n-1));
else uni2orig[i] = (i - (n-1)*nprocs/n) * n + n-1;
}
} else if (strcmp(style,"custom") == 0) {
if (me == 0) {
FILE *fp = fopen(arg,"r");
if (fp == NULL) error->universe_one(FLERR,"Cannot open -reorder file");
// skip header = blank and comment lines
char *ptr;
if (!fgets(line,MAXLINE,fp))
error->one(FLERR,"Unexpected end of -reorder file");
while (1) {
if (ptr = strchr(line,'#')) *ptr = '\0';
if (strspn(line," \t\n\r") != strlen(line)) break;
if (!fgets(line,MAXLINE,fp))
error->one(FLERR,"Unexpected end of -reorder file");
}
// read nprocs lines
// uni2orig = inverse mapping
int me_orig,me_new;
sscanf(line,"%d %d",&me_orig,&me_new);
if (me_orig < 0 || me_orig >= nprocs ||
me_new < 0 || me_new >= nprocs)
error->one(FLERR,"Invalid entry in reorder file");
uni2orig[me_new] = me_orig;
for (int i = 1; i < nprocs; i++) {
if (!fgets(line,MAXLINE,fp))
error->one(FLERR,"Unexpected end of reorder file");
sscanf(line,"%d %d",&me_orig,&me_new);
if (me_orig < 0 || me_orig >= nprocs ||
me_new < 0 || me_new >= nprocs)
error->one(FLERR,"Invalid entry in reorder file");
uni2orig[me_new] = me_orig;
}
fclose(fp);
}
// bcast uni2org from proc 0 to all other universe procs
MPI_Bcast(uni2orig,nprocs,MPI_INT,0,uorig);
} else error->universe_all(FLERR,"Invalid command-line argument");
// create new uworld communicator
int ome,key;
MPI_Comm_rank(uorig,&ome);
for (int i = 0; i < nprocs; i++)
if (uni2orig[i] == ome) key = i;
MPI_Comm_split(uorig,0,key,&uworld);
MPI_Comm_rank(uworld,&me);
MPI_Comm_size(uworld,&nprocs);
}
/* ----------------------------------------------------------------------
add 1 or more worlds to universe
str == NULL -> add 1 world with all procs in universe
str = NxM -> add N worlds, each with M procs
str = P -> add 1 world with P procs
------------------------------------------------------------------------- */
void Universe::add_world(char *str)
{
int n,nper;
char *ptr;
if (str == NULL) {
n = 1;
nper = nprocs;
} else if ((ptr = strchr(str,'x')) != NULL) {
*ptr = '\0';
n = atoi(str);
nper = atoi(ptr+1);
} else {
n = 1;
nper = atoi(str);
}
memory->grow(procs_per_world,nworlds+n,"universe:procs_per_world");
memory->grow(root_proc,(nworlds+n),"universe:root_proc");
for (int i = 0; i < n; i++) {
procs_per_world[nworlds] = nper;
if (nworlds == 0) root_proc[nworlds] = 0;
else
root_proc[nworlds] = root_proc[nworlds-1] + procs_per_world[nworlds-1];
if (me >= root_proc[nworlds]) iworld = nworlds;
nworlds++;
}
}
/* ----------------------------------------------------------------------
check if total procs in all worlds = procs in universe
------------------------------------------------------------------------- */
int Universe::consistent()
{
int n = 0;
for (int i = 0; i < nworlds; i++) n += procs_per_world[i];
if (n == nprocs) return 1;
else return 0;
}

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